refactor && enhance mysql sql parser support

src/main/java/com/alibaba/druid/sql/ast/expr/SQLBitStringLiteralExpr.java

@@ -17,6 +17,7 @@ package com.alibaba.druid.sql.ast.expr;
 
 import java.util.BitSet;
 
+import com.alibaba.druid.sql.ast.SQLExprImpl;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
 /**
@@ -28,7 +29,7 @@ import com.alibaba.druid.sql.visitor.SQLASTVisitor;
  * 
  * @author WENSHAO
  */
-public class SQLBitStringLiteralExpr extends SQLLiteralExpr {
+public class SQLBitStringLiteralExpr extends SQLExprImpl implements SQLLiteralExpr {
 
     private static final long serialVersionUID = 1L;
 

src/main/java/com/alibaba/druid/sql/ast/expr/SQLDateLiteralExpr.java

@@ -15,9 +15,10 @@
  */
 package com.alibaba.druid.sql.ast.expr;
 
+import com.alibaba.druid.sql.ast.SQLExprImpl;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
-public class SQLDateLiteralExpr extends SQLLiteralExpr {
+public class SQLDateLiteralExpr extends SQLExprImpl implements SQLLiteralExpr {
 
     private static final long   serialVersionUID = 1L;
 

src/main/java/com/alibaba/druid/sql/ast/expr/SQLDefaultExpr.java

@@ -1,8 +1,9 @@
 package com.alibaba.druid.sql.ast.expr;
 
+import com.alibaba.druid.sql.ast.SQLExprImpl;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
-public class SQLDefaultExpr extends SQLLiteralExpr {
+public class SQLDefaultExpr extends SQLExprImpl implements SQLLiteralExpr {
 
     private static final long serialVersionUID = 1L;
 

src/main/java/com/alibaba/druid/sql/ast/expr/SQLHexExpr.java

@@ -15,9 +15,12 @@
  */
 package com.alibaba.druid.sql.ast.expr;
 
+import com.alibaba.druid.sql.ast.SQLExprImpl;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
+import com.alibaba.druid.util.HexBin;
+import com.alibaba.druid.util.IOUtils;
 
-public class SQLHexExpr extends SQLLiteralExpr {
+public class SQLHexExpr extends SQLExprImpl implements SQLLiteralExpr {
 
     private static final long serialVersionUID = 1L;
 
@@ -76,4 +79,8 @@ public class SQLHexExpr extends SQLLiteralExpr {
         }
         return true;
     }
+    
+    public byte[] toBytes() {
+        return HexBin.decode(this.hex);
+    }
 }

src/main/java/com/alibaba/druid/sql/ast/expr/SQLHexStringLiteralExpr.java

@@ -15,9 +15,10 @@
  */
 package com.alibaba.druid.sql.ast.expr;
 
+import com.alibaba.druid.sql.ast.SQLExprImpl;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
-public class SQLHexStringLiteralExpr extends SQLLiteralExpr {
+public class SQLHexStringLiteralExpr extends SQLExprImpl implements SQLLiteralExpr {
 
     private static final long serialVersionUID = 1L;
 

src/main/java/com/alibaba/druid/sql/ast/expr/SQLIntervalLiteralExpr.java

@@ -15,6 +15,7 @@
  */
 package com.alibaba.druid.sql.ast.expr;
 
+import com.alibaba.druid.sql.ast.SQLExprImpl;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
 /**
@@ -22,7 +23,7 @@ import com.alibaba.druid.sql.visitor.SQLASTVisitor;
  * 
  * @author WENSHAO
  */
-public class SQLIntervalLiteralExpr extends SQLLiteralExpr {
+public class SQLIntervalLiteralExpr extends SQLExprImpl implements SQLLiteralExpr {
 
     private static final long serialVersionUID = 1L;
 

src/main/java/com/alibaba/druid/sql/ast/expr/SQLLiteralExpr.java

@@ -15,14 +15,9 @@
  */
 package com.alibaba.druid.sql.ast.expr;
 
-import com.alibaba.druid.sql.ast.SQLExprImpl;
+import com.alibaba.druid.sql.ast.SQLExpr;
 
-public abstract class SQLLiteralExpr extends SQLExprImpl {
+public interface SQLLiteralExpr extends SQLExpr {
 
-    private static final long serialVersionUID = 1L;
-
-    public SQLLiteralExpr(){
-
-    }
 
 }

src/main/java/com/alibaba/druid/sql/ast/expr/SQLNullExpr.java

@@ -15,9 +15,10 @@
  */
 package com.alibaba.druid.sql.ast.expr;
 
+import com.alibaba.druid.sql.ast.SQLExprImpl;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
-public class SQLNullExpr extends SQLLiteralExpr {
+public class SQLNullExpr extends SQLExprImpl implements SQLLiteralExpr {
 
     private static final long serialVersionUID = 1L;
 

src/main/java/com/alibaba/druid/sql/ast/expr/SQLNumericLiteralExpr.java

@@ -15,7 +15,9 @@
  */
 package com.alibaba.druid.sql.ast.expr;
 
-public abstract class SQLNumericLiteralExpr extends SQLLiteralExpr {
+import com.alibaba.druid.sql.ast.SQLExprImpl;
+
+public abstract class SQLNumericLiteralExpr extends SQLExprImpl implements SQLLiteralExpr {
 
     private static final long serialVersionUID = 1L;
 

src/main/java/com/alibaba/druid/sql/ast/expr/SQLTextLiteralExpr.java

@@ -15,7 +15,9 @@
  */
 package com.alibaba.druid.sql.ast.expr;
 
-public abstract class SQLTextLiteralExpr extends SQLLiteralExpr {
+import com.alibaba.druid.sql.ast.SQLExprImpl;
+
+public abstract class SQLTextLiteralExpr extends SQLExprImpl implements SQLLiteralExpr {
 
     private static final long serialVersionUID = 1L;
 

src/main/java/com/alibaba/druid/sql/ast/expr/SQLVariantRefExpr.java

@@ -24,10 +24,16 @@ public class SQLVariantRefExpr extends SQLExprImpl {
 
     private String            name;
 
-    public SQLVariantRefExpr(String name){
+    private boolean           global           = false;
 
+    public SQLVariantRefExpr(String name){
         this.name = name;
     }
+    
+    public SQLVariantRefExpr(String name, boolean global){
+        this.name = name;
+        this.global = global;
+    }
 
     public SQLVariantRefExpr(){
 
@@ -82,4 +88,12 @@ public class SQLVariantRefExpr extends SQLExprImpl {
         return true;
     }
 
+    public boolean isGlobal() {
+        return global;
+    }
+
+    public void setGlobal(boolean global) {
+        this.global = global;
+    }
+
 }

src/main/java/com/alibaba/druid/sql/dialect/mysql/ast/expr/MySqlBinaryExpr.java

@@ -19,7 +19,7 @@ import com.alibaba.druid.sql.ast.expr.SQLLiteralExpr;
 import com.alibaba.druid.sql.dialect.mysql.visitor.MySqlASTVisitor;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
-public class MySqlBinaryExpr extends SQLLiteralExpr implements MySqlExpr {
+public class MySqlBinaryExpr extends MySqlExprImpl implements MySqlExpr, SQLLiteralExpr {
 
     private static final long serialVersionUID = 1L;
 
@@ -47,7 +47,7 @@ public class MySqlBinaryExpr extends SQLLiteralExpr implements MySqlExpr {
         this.accept0((MySqlASTVisitor) visitor);
     }
 
-    protected void accept0(MySqlASTVisitor visitor) {
+    public void accept0(MySqlASTVisitor visitor) {
         visitor.visit(this);
 
         visitor.endVisit(this);

src/main/java/com/alibaba/druid/sql/dialect/mysql/ast/expr/MySqlBooleanExpr.java

@@ -19,7 +19,7 @@ import com.alibaba.druid.sql.ast.expr.SQLLiteralExpr;
 import com.alibaba.druid.sql.dialect.mysql.visitor.MySqlASTVisitor;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
-public class MySqlBooleanExpr extends SQLLiteralExpr implements MySqlExpr {
+public class MySqlBooleanExpr extends MySqlExprImpl implements MySqlExpr, SQLLiteralExpr {
 
     private static final long serialVersionUID = 1L;
 
@@ -46,7 +46,7 @@ public class MySqlBooleanExpr extends SQLLiteralExpr implements MySqlExpr {
         this.accept0((MySqlASTVisitor) visitor);
     }
 
-    protected void accept0(MySqlASTVisitor visitor) {
+    public void accept0(MySqlASTVisitor visitor) {
         visitor.visit(this);
 
         visitor.endVisit(this);

src/main/java/com/alibaba/druid/sql/dialect/mysql/ast/expr/MySqlExprImpl.java

@@ -0,0 +1,10 @@
+package com.alibaba.druid.sql.dialect.mysql.ast.expr;
+
+import com.alibaba.druid.sql.ast.SQLExpr;
+import com.alibaba.druid.sql.dialect.mysql.ast.MySqlObjectImpl;
+
+public abstract class MySqlExprImpl extends MySqlObjectImpl implements SQLExpr {
+
+    private static final long serialVersionUID = 1L;
+
+}

src/main/java/com/alibaba/druid/sql/dialect/mysql/ast/expr/MySqlHexadecimalExpr.java

@@ -0,0 +1,16 @@
+package com.alibaba.druid.sql.dialect.mysql.ast.expr;
+
+import com.alibaba.druid.sql.ast.expr.SQLLiteralExpr;
+import com.alibaba.druid.sql.dialect.mysql.visitor.MySqlASTVisitor;
+
+
+public class MySqlHexadecimalExpr extends MySqlExprImpl implements SQLLiteralExpr {
+
+    private static final long serialVersionUID = 1L;
+
+    @Override
+    public void accept0(MySqlASTVisitor visitor) {
+        
+    }
+
+}

src/main/java/com/alibaba/druid/sql/dialect/mysql/ast/statement/MySqlSetTransactionIsolationLevelStatement.java

@@ -0,0 +1,34 @@
+package com.alibaba.druid.sql.dialect.mysql.ast.statement;
+
+import com.alibaba.druid.sql.dialect.mysql.visitor.MySqlASTVisitor;
+
+public class MySqlSetTransactionIsolationLevelStatement extends MySqlStatementImpl {
+
+    private static final long serialVersionUID = 1L;
+
+    private Boolean           global;
+
+    private String            level;
+
+    public String getLevel() {
+        return level;
+    }
+
+    public void setLevel(String level) {
+        this.level = level;
+    }
+
+    public void accept0(MySqlASTVisitor visitor) {
+        visitor.visit(this);
+        visitor.endVisit(this);
+    }
+
+    public Boolean getGlobal() {
+        return global;
+    }
+
+    public void setGlobal(Boolean global) {
+        this.global = global;
+    }
+
+}

src/main/java/com/alibaba/druid/sql/dialect/mysql/parser/MySqlExprParser.java

@@ -24,6 +24,7 @@ import com.alibaba.druid.sql.ast.expr.SQLIdentifierExpr;
 import com.alibaba.druid.sql.ast.expr.SQLIntegerExpr;
 import com.alibaba.druid.sql.ast.expr.SQLMethodInvokeExpr;
 import com.alibaba.druid.sql.ast.expr.SQLVariantRefExpr;
+import com.alibaba.druid.sql.ast.statement.SQLAssignItem;
 import com.alibaba.druid.sql.ast.statement.SQLColumnDefinition;
 import com.alibaba.druid.sql.dialect.mysql.ast.expr.MySqlBinaryExpr;
 import com.alibaba.druid.sql.dialect.mysql.ast.expr.MySqlBooleanExpr;
@@ -132,6 +133,21 @@ public class MySqlExprParser extends SQLExprParser {
                 String aliasValue = lexer.stringVal();
                 lexer.nextToken();
                 return primaryRest(new SQLCharExpr(aliasValue));
+            case VARIANT:
+                SQLVariantRefExpr varRefExpr = new SQLVariantRefExpr(lexer.stringVal());
+                lexer.nextToken();
+                if (varRefExpr.getName().equalsIgnoreCase("@@global")) {
+                    accept(Token.DOT);
+                    varRefExpr = new SQLVariantRefExpr(lexer.stringVal(), true);
+                    lexer.nextToken();
+                } else if (varRefExpr.getName().equals("@") && lexer.token() == Token.LITERAL_CHARS) {
+                    varRefExpr.setName("@'" + lexer.stringVal() + "'");
+                    lexer.nextToken();
+                } else if (varRefExpr.getName().equals("@@") && lexer.token() == Token.LITERAL_CHARS) {
+                    varRefExpr.setName("@@'" + lexer.stringVal() + "'");
+                    lexer.nextToken();
+                } 
+                return primaryRest(varRefExpr);
             default:
                 return super.primary();
         }
@@ -496,4 +512,35 @@ public class MySqlExprParser extends SQLExprParser {
 
         return expr;
     }
+    
+    public SQLAssignItem parseAssignItem() {
+        SQLAssignItem item = new SQLAssignItem();
+        
+        SQLExpr var = primary();
+        
+        if (var instanceof SQLIdentifierExpr) {
+            String ident = ((SQLIdentifierExpr) var).getName();
+            
+            if ("GLOBAL".equalsIgnoreCase(ident)) {
+                ident = lexer.stringVal();
+                lexer.nextToken();
+                var = new SQLVariantRefExpr(ident, true);
+            } else if ("SESSION".equalsIgnoreCase(ident)) {
+                    ident = lexer.stringVal();
+                    lexer.nextToken();
+                    var = new SQLVariantRefExpr(ident, false);
+            } else {
+                var = new SQLVariantRefExpr(ident);
+            }
+        }
+        item.setTarget(var);
+        if (lexer.token() == Token.COLONEQ) {
+            lexer.nextToken();
+        } else {
+            accept(Token.EQ);
+        }
+        item.setValue(expr());
+
+        return item;
+    }
 }

src/main/java/com/alibaba/druid/sql/dialect/mysql/parser/MySqlLexer.java

@@ -95,7 +95,6 @@ public class MySqlLexer extends Lexer {
         map.put("CAST", Token.CAST);
         map.put("IN", Token.IN);
         map.put("ASC", Token.ASC);
-        map.put("DESC", Token.DESC);
         map.put("LIKE", Token.LIKE);
         map.put("ESCAPE", Token.ESCAPE);
         map.put("BETWEEN", Token.BETWEEN);
@@ -128,6 +127,71 @@ public class MySqlLexer extends Lexer {
         super.keywods = DEFAULT_MYSQL_KEYWORDS;
     }
 
+    public void scanVariable() {
+        final char first = ch;
+
+        if (ch != '@' && ch != ':' && ch != '#') {
+            throw new SQLParseException("illegal variable");
+        }
+
+        int hash = first;
+
+        np = bp;
+        sp = 1;
+
+        if (buf[bp + 1] == '@') {
+            ch = buf[++bp];
+            hash = 31 * hash + ch;
+
+            sp++;
+        }
+
+        if (buf[bp + 1] == '`') {
+            ++bp;
+            ++sp;
+            char ch;
+            for (;;) {
+                ch = buf[++bp];
+
+                if (ch == '`') {
+                    sp++;
+                    ch = buf[++bp];
+                    break;
+                } else if (ch == EOI) {
+                    throw new SQLParseException("illegal identifier");
+                }
+
+                hash = 31 * hash + ch;
+
+                sp++;
+                continue;
+            }
+
+            this.ch = buf[bp];
+
+            stringVal = symbolTable.addSymbol(buf, np, sp, hash);
+            token = Token.VARIANT;
+        } else {
+            for (;;) {
+                ch = buf[++bp];
+
+                if (!isIdentifierChar(ch)) {
+                    break;
+                }
+
+                hash = 31 * hash + ch;
+
+                sp++;
+                continue;
+            }
+        }
+
+        this.ch = buf[bp];
+
+        stringVal = symbolTable.addSymbol(buf, np, sp, hash);
+        token = Token.VARIANT;
+    }
+
     public void scanIdentifier() {
         final char first = ch;
 

src/main/java/com/alibaba/druid/sql/dialect/mysql/parser/MySqlStatementParser.java

@@ -25,10 +25,12 @@ import com.alibaba.druid.sql.ast.expr.SQLCharExpr;
 import com.alibaba.druid.sql.ast.expr.SQLIdentifierExpr;
 import com.alibaba.druid.sql.ast.expr.SQLLiteralExpr;
 import com.alibaba.druid.sql.ast.expr.SQLQueryExpr;
+import com.alibaba.druid.sql.ast.expr.SQLVariantRefExpr;
 import com.alibaba.druid.sql.ast.statement.SQLCreateTableStatement;
 import com.alibaba.druid.sql.ast.statement.SQLDropTableStatement;
 import com.alibaba.druid.sql.ast.statement.SQLInsertStatement;
 import com.alibaba.druid.sql.ast.statement.SQLSelectStatement;
+import com.alibaba.druid.sql.ast.statement.SQLSetStatement;
 import com.alibaba.druid.sql.ast.statement.SQLTableSource;
 import com.alibaba.druid.sql.ast.statement.SQLUpdateSetItem;
 import com.alibaba.druid.sql.ast.statement.SQLUpdateStatement;
@@ -50,6 +52,7 @@ import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlReplicateStatement
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlResetStatement;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlRollbackStatement;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlSelectQueryBlock;
+import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlSetTransactionIsolationLevelStatement;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlShowColumnsStatement;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlShowDatabasesStatement;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlShowStatusStatement;
@@ -84,11 +87,11 @@ public class MySqlStatementParser extends SQLStatementParser {
     public SQLSelectStatement parseSelect() throws ParserException {
         return new SQLSelectStatement(new MySqlSelectParser(lexer).select());
     }
-    
+
     public SQLUpdateStatement parseUpdateStatement() throws ParserException {
-    	MySqlUpdateStatement stmt = (MySqlUpdateStatement) super.parseUpdateStatement();
-    	
-    	if (lexer.token() == Token.LIMIT) {
+        MySqlUpdateStatement stmt = (MySqlUpdateStatement) super.parseUpdateStatement();
+
+        if (lexer.token() == Token.LIMIT) {
             lexer.nextToken();
 
             MySqlSelectQueryBlock.Limit limit = new MySqlSelectQueryBlock.Limit();
@@ -105,16 +108,16 @@ public class MySqlStatementParser extends SQLStatementParser {
             } else {
                 limit.setRowCount(temp);
             }
-            
+
             stmt.setLimit(limit);
-    	}
-    	
-    	return stmt;
+        }
+
+        return stmt;
+    }
+
+    protected MySqlUpdateStatement createUpdateStatement() {
+        return new MySqlUpdateStatement();
     }
-    
-	protected MySqlUpdateStatement createUpdateStatement() {
-		return new MySqlUpdateStatement();
-	}
 
     public MySqlDeleteStatement parseDeleteStatement() throws ParserException {
         MySqlDeleteStatement deleteStatement = new MySqlDeleteStatement();
@@ -375,7 +378,7 @@ public class MySqlStatementParser extends SQLStatementParser {
             return true;
         }
 
-        if (identifierEquals("DESCRIBE")) {
+        if (identifierEquals("DESC") || identifierEquals("DESCRIBE")) {
             SQLStatement stmt = parseDescribe();
             statementList.add(stmt);
             return true;
@@ -384,8 +387,12 @@ public class MySqlStatementParser extends SQLStatementParser {
         return false;
     }
 
-    public SQLStatement parseDescribe() throws ParserException {
-        acceptIdentifier("DESCRIBE");
+    public MySqlDescribeStatement parseDescribe() throws ParserException {
+        if (identifierEquals("DESC") || identifierEquals("DESCRIBE")) {
+            lexer.nextToken();
+        } else {
+            throw new ParserException("expect DESC, actual " + lexer.token());
+        }
 
         MySqlDescribeStatement stmt = new MySqlDescribeStatement();
         stmt.setObject(this.exprParser.name());
@@ -1067,4 +1074,72 @@ public class MySqlStatementParser extends SQLStatementParser {
     public SQLSelectParser createSQLSelectParser() {
         return new MySqlSelectParser(this.lexer);
     }
+
+    public SQLStatement parseSet() throws ParserException {
+        accept(Token.SET);
+
+        Boolean global = null;
+        if (identifierEquals("GLOBAL")) {
+            global = Boolean.TRUE;
+            lexer.nextToken();
+        } else if (identifierEquals("SESSION")) {
+            global = Boolean.FALSE;
+            lexer.nextToken();
+        }
+
+        if (identifierEquals("TRANSACTION")) {
+            lexer.nextToken();
+            acceptIdentifier("ISOLATION");
+            acceptIdentifier("LEVEL");
+            
+            MySqlSetTransactionIsolationLevelStatement stmt = new MySqlSetTransactionIsolationLevelStatement();
+            stmt.setGlobal(global);
+            
+            if (identifierEquals("READ")) {
+                lexer.nextToken();
+                
+                if (identifierEquals("UNCOMMITTED")) {
+                    stmt.setLevel("READ UNCOMMITTED");
+                    lexer.nextToken();
+                } else if (identifierEquals("WRITE")) {
+                    stmt.setLevel("READ WRITE");
+                    lexer.nextToken();
+                } else if (identifierEquals("ONLY")) {
+                    stmt.setLevel("READ ONLY");
+                    lexer.nextToken();
+                } else if (identifierEquals("COMMITTED")) {
+                    stmt.setLevel("READ COMMITTED");
+                    lexer.nextToken();
+                } else {
+                    throw new ParserException("UNKOWN TRANSACTION LEVEL : " + lexer.stringVal());
+                }
+            } else if (identifierEquals("SERIALIZABLE")) {
+                stmt.setLevel("SERIALIZABLE");
+                lexer.nextToken();
+            } else if (identifierEquals("REPEATABLE")) {
+                lexer.nextToken();
+                if (identifierEquals("READ")) {
+                    stmt.setLevel("REPEATABLE READ");
+                    lexer.nextToken();
+                } else {
+                    throw new ParserException("UNKOWN TRANSACTION LEVEL : " + lexer.stringVal());
+                }
+            } else {
+                throw new ParserException("UNKOWN TRANSACTION LEVEL : " + lexer.stringVal());
+            }
+            
+            return stmt;
+        } else {
+            SQLSetStatement stmt = new SQLSetStatement();
+
+            parseAssignItems(stmt.getItems());
+            
+            if (global != null && global.booleanValue()) {
+                SQLVariantRefExpr varRef = (SQLVariantRefExpr) stmt.getItems().get(0).getTarget();
+                varRef.setGlobal(true);
+            }
+
+            return stmt;
+        }
+    }
 }

src/main/java/com/alibaba/druid/sql/dialect/mysql/visitor/MySqlASTVisitor.java

@@ -43,6 +43,7 @@ import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlResetStatement;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlRollbackStatement;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlSelectGroupBy;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlSelectQueryBlock;
+import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlSetTransactionIsolationLevelStatement;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlShowColumnsStatement;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlShowDatabasesStatement;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlShowStatusStatement;
@@ -206,4 +207,8 @@ public interface MySqlASTVisitor extends SQLASTVisitor {
     boolean visit(MySqlUpdateStatement x);
     
     void endVisit(MySqlUpdateStatement x);
+    
+    boolean visit(MySqlSetTransactionIsolationLevelStatement x);
+    
+    void endVisit(MySqlSetTransactionIsolationLevelStatement x);
 }

src/main/java/com/alibaba/druid/sql/dialect/mysql/visitor/MySqlASTVisitorAdapter.java

@@ -30,6 +30,7 @@ import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlRollbackStatement;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlSelectGroupBy;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlSelectQueryBlock;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlSelectQueryBlock.Limit;
+import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlSetTransactionIsolationLevelStatement;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlShowColumnsStatement;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlShowDatabasesStatement;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlShowStatusStatement;
@@ -444,4 +445,14 @@ public class MySqlASTVisitorAdapter extends SQLASTVisitorAdapter implements
 		
 	}
 
+    @Override
+    public boolean visit(MySqlSetTransactionIsolationLevelStatement x) {
+        return true;
+    }
+
+    @Override
+    public void endVisit(MySqlSetTransactionIsolationLevelStatement x) {
+        
+    }
+
 }

src/main/java/com/alibaba/druid/sql/dialect/mysql/visitor/MySqlOutputVisitor.java

@@ -62,6 +62,7 @@ import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlSQLColumnDefinitio
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlSelectGroupBy;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlSelectQueryBlock;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlSelectQueryBlock.Limit;
+import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlSetTransactionIsolationLevelStatement;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlShowColumnsStatement;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlShowDatabasesStatement;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlShowStatusStatement;
@@ -100,7 +101,7 @@ public class MySqlOutputVisitor extends SQLASTOutputVisitor implements MySqlASTV
         if (x.getOrderBy() != null) {
             x.getOrderBy().setParent(x);
         }
-        
+
         print("SELECT ");
 
         if (SQLSetQuantifier.ALL == x.getDistionOption()) print("ALL ");
@@ -425,7 +426,30 @@ public class MySqlOutputVisitor extends SQLASTOutputVisitor implements MySqlASTV
     }
 
     public boolean visit(SQLVariantRefExpr x) {
-        print(x.getName());
+        if (x.isGlobal()) {
+            print("@@global.");
+        } else {
+            if ((!x.getName().startsWith("@")) && (!x.getName().equals("?"))) {
+                print("@@");
+            }
+        }
+
+        for (int i = 0; i < x.getName().length(); ++i) {
+            char ch = x.getName().charAt(i);
+            if (ch == '\'') {
+                if (x.getName().startsWith("@@") && i == 2) {
+                    print(ch);
+                } else if (x.getName().startsWith("@") && i == 1) {
+                    print(ch);
+                } else if (i != 0 && i != x.getName().length() - 1) {
+                    print("\\'");
+                } else {
+                    print(ch);
+                }
+            } else {
+                print(ch);
+            }
+        }
 
         String collate = (String) x.getAttribute("COLLATE");
         if (collate != null) {
@@ -1250,12 +1274,12 @@ public class MySqlOutputVisitor extends SQLASTOutputVisitor implements MySqlASTV
     @Override
     public boolean visit(UserSpecification x) {
         x.getUser().accept(this);
-        
+
         if (x.getPassword() != null) {
             print(" IDENTIFIED BY ");
             x.getPassword().accept(this);
         }
-        
+
         if (x.getAuthPlugin() != null) {
             print(" IDENTIFIED WITH ");
             x.getAuthPlugin().accept(this);
@@ -1265,7 +1289,7 @@ public class MySqlOutputVisitor extends SQLASTOutputVisitor implements MySqlASTV
 
     @Override
     public void endVisit(MySqlDropUser x) {
-        
+
     }
 
     @Override
@@ -1277,7 +1301,7 @@ public class MySqlOutputVisitor extends SQLASTOutputVisitor implements MySqlASTV
 
     @Override
     public void endVisit(MySqlDropTableStatement x) {
-        
+
     }
 
     @Override
@@ -1286,14 +1310,14 @@ public class MySqlOutputVisitor extends SQLASTOutputVisitor implements MySqlASTV
         if (x.isIfExists()) {
             print("IF EXISTS ");
         }
-        
+
         printAndAccept(x.getTableSources(), ", ");
         return false;
     }
 
     @Override
     public void endVisit(MySqlPartitionByKey x) {
-        
+
     }
 
     @Override
@@ -1301,7 +1325,7 @@ public class MySqlOutputVisitor extends SQLASTOutputVisitor implements MySqlASTV
         print("PARTITION BY KEY (");
         printAndAccept(x.getColumns(), ", ");
         print(")");
-        
+
         if (x.getPartitionCount() != null) {
             print(" PARTITIONS ");
             x.getPartitionCount().accept(this);
@@ -1311,21 +1335,20 @@ public class MySqlOutputVisitor extends SQLASTOutputVisitor implements MySqlASTV
 
     @Override
     public void endVisit(MySqlSelectQueryBlock x) {
-        
+
     }
 
     @Override
     public boolean visit(MySqlOutFileExpr x) {
         print("OUTFILE ");
         x.getFile().accept(this);
-        
+
         if (x.getCharset() != null) {
             print(" CHARACTER SET ");
             print(x.getCharset());
         }
 
-        if (x.getColumnsTerminatedBy() != null || x.getColumnsEnclosedBy() != null
-            || x.getColumnsEscaped() != null) {
+        if (x.getColumnsTerminatedBy() != null || x.getColumnsEnclosedBy() != null || x.getColumnsEscaped() != null) {
             print(" COLUMNS");
             if (x.getColumnsTerminatedBy() != null) {
                 print(" TERMINATED BY ");
@@ -1358,39 +1381,56 @@ public class MySqlOutputVisitor extends SQLASTOutputVisitor implements MySqlASTV
                 x.getLinesTerminatedBy().accept(this);
             }
         }
-        
+
         return false;
     }
 
     @Override
     public void endVisit(MySqlOutFileExpr x) {
-        
+
     }
 
     @Override
     public boolean visit(MySqlDescribeStatement x) {
-        print("DESCRIBE ");
+        print("DESC ");
         x.getObject().accept(this);
         return false;
     }
 
     @Override
     public void endVisit(MySqlDescribeStatement x) {
-        
+
     }
 
-	@Override
-	public boolean visit(MySqlUpdateStatement x) {
-		super.visit((SQLUpdateStatement) x);
-		if (x.getLimit() != null) {
-			println();
-			x.getLimit().accept(this);
-		}
-		return false;
-	}
+    @Override
+    public boolean visit(MySqlUpdateStatement x) {
+        super.visit((SQLUpdateStatement) x);
+        if (x.getLimit() != null) {
+            println();
+            x.getLimit().accept(this);
+        }
+        return false;
+    }
 
-	@Override
-	public void endVisit(MySqlUpdateStatement x) {
-		
-	}
+    @Override
+    public void endVisit(MySqlUpdateStatement x) {
+
+    }
+
+    @Override
+    public boolean visit(MySqlSetTransactionIsolationLevelStatement x) {
+        return false;
+    }
+
+    @Override
+    public void endVisit(MySqlSetTransactionIsolationLevelStatement x) {
+        if (x.getGlobal() == null) {
+            print("SET TRANSACTION ISOLATION LEVEL ");
+        } else if (x.getGlobal().booleanValue()) {
+            print("SET GLOBAL TRANSACTION ISOLATION LEVEL ");
+        } else {
+            print("SET SESSION TRANSACTION ISOLATION LEVEL ");
+        }
+        print(x.getLevel());
+    }
 }

src/main/java/com/alibaba/druid/sql/dialect/mysql/visitor/MySqlSchemaStatVisitor.java

@@ -39,6 +39,7 @@ import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlRollbackStatement;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlSelectGroupBy;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlSelectQueryBlock;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlSelectQueryBlock.Limit;
+import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlSetTransactionIsolationLevelStatement;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlShowColumnsStatement;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlShowDatabasesStatement;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlShowStatusStatement;
@@ -505,4 +506,14 @@ public class MySqlSchemaStatVisitor extends SchemaStatVisitor implements MySqlAS
 	public void endVisit(MySqlUpdateStatement x) {
 		
 	}
+
+    @Override
+    public boolean visit(MySqlSetTransactionIsolationLevelStatement x) {
+        return false;
+    }
+
+    @Override
+    public void endVisit(MySqlSetTransactionIsolationLevelStatement x) {
+        
+    }
 }

src/main/java/com/alibaba/druid/sql/dialect/oracle/ast/expr/OracleDateExpr.java

@@ -15,11 +15,12 @@
  */
 package com.alibaba.druid.sql.dialect.oracle.ast.expr;
 
+import com.alibaba.druid.sql.ast.SQLExprImpl;
 import com.alibaba.druid.sql.ast.expr.SQLLiteralExpr;
 import com.alibaba.druid.sql.dialect.oracle.visitor.OracleASTVisitor;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
-public class OracleDateExpr extends SQLLiteralExpr implements OracleExpr {
+public class OracleDateExpr extends SQLExprImpl implements SQLLiteralExpr, OracleExpr {
 
     private static final long serialVersionUID = 1L;
 

src/main/java/com/alibaba/druid/sql/dialect/oracle/ast/expr/OracleIntervalExpr.java

@@ -16,11 +16,12 @@
 package com.alibaba.druid.sql.dialect.oracle.ast.expr;
 
 import com.alibaba.druid.sql.ast.SQLExpr;
+import com.alibaba.druid.sql.ast.SQLExprImpl;
 import com.alibaba.druid.sql.ast.expr.SQLLiteralExpr;
 import com.alibaba.druid.sql.dialect.oracle.visitor.OracleASTVisitor;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
-public class OracleIntervalExpr extends SQLLiteralExpr implements OracleExpr {
+public class OracleIntervalExpr extends SQLExprImpl implements SQLLiteralExpr, OracleExpr {
 
     private static final long  serialVersionUID = 1L;
     private SQLExpr            value;

src/main/java/com/alibaba/druid/sql/dialect/oracle/ast/expr/OracleTimestampExpr.java

@@ -15,11 +15,12 @@
  */
 package com.alibaba.druid.sql.dialect.oracle.ast.expr;
 
+import com.alibaba.druid.sql.ast.SQLExprImpl;
 import com.alibaba.druid.sql.ast.expr.SQLLiteralExpr;
 import com.alibaba.druid.sql.dialect.oracle.visitor.OracleASTVisitor;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
-public class OracleTimestampExpr extends SQLLiteralExpr implements OracleExpr {
+public class OracleTimestampExpr extends SQLExprImpl implements SQLLiteralExpr, OracleExpr {
 
     private static final long serialVersionUID = 1L;
     private String            literal;

src/main/java/com/alibaba/druid/sql/parser/SQLExprParser.java

@@ -55,6 +55,7 @@ import com.alibaba.druid.sql.ast.expr.SQLUnaryExpr;
 import com.alibaba.druid.sql.ast.expr.SQLUnaryOperator;
 import com.alibaba.druid.sql.ast.expr.SQLVariantRefExpr;
 import com.alibaba.druid.sql.ast.statement.NotNullConstraint;
+import com.alibaba.druid.sql.ast.statement.SQLAssignItem;
 import com.alibaba.druid.sql.ast.statement.SQLCharactorDataType;
 import com.alibaba.druid.sql.ast.statement.SQLColumnDefinition;
 import com.alibaba.druid.sql.ast.statement.SQLPrimaryKey;
@@ -195,8 +196,16 @@ public class SQLExprParser extends SQLParser {
                 lexer.nextToken();
                 break;
             case VARIANT:
-                sqlExpr = new SQLVariantRefExpr(lexer.stringVal());
+                SQLVariantRefExpr varRefExpr = new SQLVariantRefExpr(lexer.stringVal());
                 lexer.nextToken();
+                if (varRefExpr.getName().equals("@") && lexer.token() == Token.LITERAL_CHARS) {
+                    varRefExpr.setName("@'" + lexer.stringVal() + "'");
+                    lexer.nextToken();
+                } else if (varRefExpr.getName().equals("@@") && lexer.token() == Token.LITERAL_CHARS) {
+                    varRefExpr.setName("@@'" + lexer.stringVal() + "'");
+                    lexer.nextToken();
+                } 
+                sqlExpr = varRefExpr;
                 break;
             case DEFAULT:
                 sqlExpr = new SQLDefaultExpr();
@@ -473,10 +482,6 @@ public class SQLExprParser extends SQLParser {
 
             expr = dotRest(expr);
             return primaryRest(expr);
-        } else if (lexer.token() == Token.COLONEQ) {
-            lexer.nextToken();
-            SQLExpr rightExp = primary();
-            expr = new SQLBinaryOpExpr(expr, SQLBinaryOperator.Assignment, rightExp);
         } else {
             if (lexer.token() == Token.LPAREN) {
                 return methodRest(expr, true);
@@ -779,6 +784,10 @@ public class SQLExprParser extends SQLParser {
             rightExp = equalityRest(rightExp);
 
             expr = new SQLBinaryOpExpr(expr, SQLBinaryOperator.NotEqual, rightExp);
+        } else if (lexer.token() == Token.COLONEQ) {
+            lexer.nextToken();
+            rightExp = expr();
+            expr = new SQLBinaryOpExpr(expr, SQLBinaryOperator.Assignment, rightExp);
         }
 
         return expr;
@@ -920,40 +929,40 @@ public class SQLExprParser extends SQLParser {
             lexer.nextToken();
             rightExp = bitOr();
             expr = new SQLBinaryOpExpr(expr, SQLBinaryOperator.LessThan, rightExp);
-//            expr = relationalRest(expr);
+            // expr = relationalRest(expr);
         } else if (lexer.token() == Token.LTEQ) {
             lexer.nextToken();
             rightExp = bitOr();
 
-//            rightExp = relationalRest(rightExp);
+            // rightExp = relationalRest(rightExp);
 
             expr = new SQLBinaryOpExpr(expr, SQLBinaryOperator.LessThanOrEqual, rightExp);
         } else if (lexer.token() == Token.LTEQGT) {
             lexer.nextToken();
             rightExp = bitOr();
 
-//            rightExp = relationalRest(rightExp);
+            // rightExp = relationalRest(rightExp);
 
             expr = new SQLBinaryOpExpr(expr, SQLBinaryOperator.LessThanOrEqualOrGreaterThan, rightExp);
         } else if (lexer.token() == Token.GT) {
             lexer.nextToken();
             rightExp = bitOr();
 
-//            rightExp = relationalRest(rightExp);
+            // rightExp = relationalRest(rightExp);
 
             expr = new SQLBinaryOpExpr(expr, SQLBinaryOperator.GreaterThan, rightExp);
         } else if (lexer.token() == Token.GTEQ) {
             lexer.nextToken();
             rightExp = bitOr();
 
-//            rightExp = relationalRest(rightExp);
+            // rightExp = relationalRest(rightExp);
 
             expr = new SQLBinaryOpExpr(expr, SQLBinaryOperator.GreaterThanOrEqual, rightExp);
         } else if (lexer.token() == Token.BANGLT) {
             lexer.nextToken();
             rightExp = bitOr();
 
-//            rightExp = relationalRest(rightExp);
+            // rightExp = relationalRest(rightExp);
 
             expr = new SQLBinaryOpExpr(expr, SQLBinaryOperator.NotLessThan, rightExp);
         } else if (lexer.token() == Token.BANGGT) {
@@ -967,14 +976,14 @@ public class SQLExprParser extends SQLParser {
             lexer.nextToken();
             rightExp = bitOr();
 
-//            rightExp = relationalRest(rightExp);
+            // rightExp = relationalRest(rightExp);
 
             expr = new SQLBinaryOpExpr(expr, SQLBinaryOperator.LessThanOrGreater, rightExp);
         } else if (lexer.token() == Token.LIKE) {
             lexer.nextToken();
             rightExp = bitOr();
 
-//            rightExp = relationalRest(rightExp);
+            // rightExp = relationalRest(rightExp);
 
             expr = new SQLBinaryOpExpr(expr, SQLBinaryOperator.Like, rightExp);
 
@@ -1168,4 +1177,23 @@ public class SQLExprParser extends SQLParser {
     public SQLPrimaryKey parsePrimaryKey() {
         throw new ParserException("TODO");
     }
+    
+    public SQLAssignItem parseAssignItem() {
+        SQLAssignItem item = new SQLAssignItem();
+        
+        SQLExpr var = primary();
+        
+        if (var instanceof SQLIdentifierExpr) {
+            var = new SQLVariantRefExpr(((SQLIdentifierExpr) var).getName());
+        }
+        item.setTarget(var);
+        if (lexer.token() == Token.COLONEQ) {
+            lexer.nextToken();
+        } else {
+            accept(Token.EQ);
+        }
+        item.setValue(expr());
+
+        return item;
+    }
 }

src/main/java/com/alibaba/druid/sql/parser/SQLParser.java

@@ -124,6 +124,13 @@ public class SQLParser {
         }
     }
 
+    public void match(Token token) {
+        if (lexer.token() != token) {
+            throw new SQLParseException("syntax error, expect " + token + ", actual " + lexer.token() + " "
+                                        + lexer.stringVal());
+        }
+    }
+
     private int errorEndPos = -1;
 
     protected void setErrorEndPos(int errPos) {
@@ -131,4 +138,5 @@ public class SQLParser {
             errorEndPos = errPos;
         }
     }
+
 }

src/main/java/com/alibaba/druid/sql/parser/SQLStatementParser.java

@@ -294,11 +294,7 @@ public class SQLStatementParser extends SQLParser {
 
     public void parseAssignItems(List<SQLAssignItem> items) {
         for (;;) {
-            SQLAssignItem item = new SQLAssignItem();
-            item.setTarget(exprParser.primary());
-            accept(Token.EQ);
-            item.setValue(exprParser.expr());
-
+            SQLAssignItem item = exprParser.parseAssignItem();
             items.add(item);
 
             if (lexer.token() == Token.COMMA) {
@@ -310,6 +306,7 @@ public class SQLStatementParser extends SQLParser {
         }
     }
 
+
     public SQLStatement parseCreate() throws ParserException {
         char mark_ch = lexer.current();
         int mark_bp = lexer.bp();

src/main/java/com/alibaba/druid/util/HexBin.java

@@ -0,0 +1,112 @@
+/*
+ * Copyright 1999-2002,2004 The Apache Software Foundation.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.alibaba.druid.util;
+
+
+/**
+ * format validation
+ *
+ * This class encodes/decodes hexadecimal data
+ * 
+ * @xerces.internal  
+ * 
+ * @author Jeffrey Rodriguez
+ * @version $Id: HexBin.java,v 1.4 2007/07/19 04:38:32 ofung Exp $
+ */
+public final class  HexBin {
+    static private final int  BASELENGTH   = 128;
+    static private final int  LOOKUPLENGTH = 16;
+    static final private byte [] hexNumberTable    = new byte[BASELENGTH];
+    static final private char [] lookUpHexAlphabet = new char[LOOKUPLENGTH];
+
+
+    static {
+        for (int i = 0; i < BASELENGTH; i++ ) {
+            hexNumberTable[i] = -1;
+        }
+        for ( int i = '9'; i >= '0'; i--) {
+            hexNumberTable[i] = (byte) (i-'0');
+        }
+        for ( int i = 'F'; i>= 'A'; i--) {
+            hexNumberTable[i] = (byte) ( i-'A' + 10 );
+        }
+        for ( int i = 'f'; i>= 'a'; i--) {
+           hexNumberTable[i] = (byte) ( i-'a' + 10 );
+        }
+
+        for(int i = 0; i<10; i++ ) {
+            lookUpHexAlphabet[i] = (char)('0'+i);
+        }
+        for(int i = 10; i<=15; i++ ) {
+            lookUpHexAlphabet[i] = (char)('A'+i -10);
+        }
+    }
+
+    /**
+     * Encode a byte array to hex string
+     *
+     * @param binaryData array of byte to encode
+     * @return return encoded string
+     */
+    static public String encode(byte[] binaryData) {
+        if (binaryData == null)
+            return null;
+        int lengthData   = binaryData.length;
+        int lengthEncode = lengthData * 2;
+        char[] encodedData = new char[lengthEncode];
+        int temp;
+        for (int i = 0; i < lengthData; i++) {
+            temp = binaryData[i];
+            if (temp < 0)
+                temp += 256;
+            encodedData[i*2] = lookUpHexAlphabet[temp >> 4];
+            encodedData[i*2+1] = lookUpHexAlphabet[temp & 0xf];
+        }
+        return new String(encodedData);
+    }
+
+    /**
+     * Decode hex string to a byte array
+     *
+     * @param encoded encoded string
+     * @return return array of byte to encode
+     */
+    static public byte[] decode(String encoded) {
+        if (encoded == null)
+            return null;
+        int lengthData = encoded.length();
+        if (lengthData % 2 != 0)
+            return null;
+
+        char[] binaryData = encoded.toCharArray();
+        int lengthDecode = lengthData / 2;
+        byte[] decodedData = new byte[lengthDecode];
+        byte temp1, temp2;
+        char tempChar;
+        for( int i = 0; i<lengthDecode; i++ ){
+            tempChar = binaryData[i*2];
+            temp1 = (tempChar < BASELENGTH) ? hexNumberTable[tempChar] : -1;
+            if (temp1 == -1)
+                return null;
+            tempChar = binaryData[i*2+1];
+            temp2 = (tempChar < BASELENGTH) ? hexNumberTable[tempChar] : -1;
+            if (temp2 == -1)
+                return null;
+            decodedData[i] = (byte)((temp1 << 4) | temp2);
+        }
+        return decodedData;
+    }
+}

src/test/java/com/alibaba/druid/bvt/sql/cobar/LiteralHexadecimalTest.java

@@ -0,0 +1,51 @@
+/**
+ * (created at 2011-11-11)
+ */
+package com.alibaba.druid.bvt.sql.cobar;
+
+import junit.framework.Assert;
+import junit.framework.TestCase;
+
+import com.alibaba.druid.sql.ast.expr.SQLHexExpr;
+import com.alibaba.druid.sql.dialect.mysql.parser.MySqlExprParser;
+
+/**
+ * @author <a href="mailto:shuo.qius@alibaba-inc.com">QIU Shuo</a>
+ */
+public class LiteralHexadecimalTest extends TestCase {
+    public void test_0() throws Exception {
+        String sql = "x'E982B1E7A195275C73'";
+        SQLHexExpr hex = (SQLHexExpr) new MySqlExprParser(sql).expr();
+        Assert.assertEquals("邱硕'\\s", new String(hex.toBytes(), "utf-8"));
+    }
+
+    public void test_1() throws Exception {
+        String sql = "x'0D0A'";
+        SQLHexExpr hex = (SQLHexExpr) new MySqlExprParser(sql).expr();
+        Assert.assertEquals("\r\n", new String(hex.toBytes(), "utf-8"));
+    }
+    
+    public void test_2() throws Exception {
+        String sql = "X'4D7953514C'";
+        SQLHexExpr hex = (SQLHexExpr) new MySqlExprParser(sql).expr();
+        Assert.assertEquals("MySQL", new String(hex.toBytes(), "utf-8"));
+    }
+    
+    public void test_3() throws Exception {
+        String sql = "0x5061756c";
+        SQLHexExpr hex = (SQLHexExpr) new MySqlExprParser(sql).expr();
+        Assert.assertEquals("Paul", new String(hex.toBytes(), "utf-8"));
+    }
+    
+    public void test_4() throws Exception {
+        String sql = "0x41";
+        SQLHexExpr hex = (SQLHexExpr) new MySqlExprParser(sql).expr();
+        Assert.assertEquals("A", new String(hex.toBytes(), "utf-8"));
+    }
+    
+    public void test_5() throws Exception {
+        String sql = "0x636174";
+        SQLHexExpr hex = (SQLHexExpr) new MySqlExprParser(sql).expr();
+        Assert.assertEquals("cat", new String(hex.toBytes(), "utf-8"));
+    }
+}