improve SQL Eval support

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

@@ -70,12 +70,9 @@ public enum SQLBinaryOperator {
     BooleanOr("OR", 160), 
     Assignment(":=", 169),
     
+    PostgresStyleTypeCast("::", 20),
     ;
 
-   
-    
-    
-
     public static int getPriority(SQLBinaryOperator operator) {
         return 0;
     }

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

@@ -323,12 +323,12 @@ public class MySqlExprParser extends SQLExprParser {
                     } else if (lexer.token() == Token.FROM) {
                         lexer.nextToken();
                         SQLExpr from = expr();
-                        methodInvokeExpr.putAttribute("FROM", from);
+                        methodInvokeExpr.getParameters().add(from);
 
                         if (lexer.token() == Token.FOR) {
                             lexer.nextToken();
                             SQLExpr forExpr = expr();
-                            methodInvokeExpr.putAttribute("FOR", forExpr);
+                            methodInvokeExpr.getParameters().add(forExpr);
                         }
                         break;
                     } else if (lexer.token() == Token.RPAREN) {

src/main/java/com/alibaba/druid/sql/dialect/postgresql/parser/PGExprParser.java

@@ -15,6 +15,9 @@
  */
 package com.alibaba.druid.sql.dialect.postgresql.parser;
 
+import com.alibaba.druid.sql.ast.SQLExpr;
+import com.alibaba.druid.sql.ast.expr.SQLBinaryOpExpr;
+import com.alibaba.druid.sql.ast.expr.SQLBinaryOperator;
 import com.alibaba.druid.sql.dialect.postgresql.ast.PGOrderBy;
 import com.alibaba.druid.sql.parser.Lexer;
 import com.alibaba.druid.sql.parser.SQLExprParser;
@@ -68,4 +71,16 @@ public class PGExprParser extends SQLExprParser {
 
         return null;
     }
+    
+    public SQLExpr primaryRest(SQLExpr expr) {
+        if (lexer.token() == Token.COLONCOLON) {
+            lexer.nextToken();
+            SQLExpr typeExpr = this.expr();
+            SQLBinaryOpExpr castExpr = new SQLBinaryOpExpr(expr, SQLBinaryOperator.PostgresStyleTypeCast, typeExpr);
+            
+            return primaryRest(castExpr);
+        }
+        
+        return super.primaryRest(expr);
+    }
 }

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

@@ -20,6 +20,7 @@ import static com.alibaba.druid.sql.parser.CharTypes.isIdentifierChar;
 import static com.alibaba.druid.sql.parser.CharTypes.isWhitespace;
 import static com.alibaba.druid.sql.parser.LayoutCharacters.EOI;
 import static com.alibaba.druid.sql.parser.Token.COLONEQ;
+import static com.alibaba.druid.sql.parser.Token.COLONCOLON;
 import static com.alibaba.druid.sql.parser.Token.COMMA;
 import static com.alibaba.druid.sql.parser.Token.EOF;
 import static com.alibaba.druid.sql.parser.Token.ERROR;
@@ -41,31 +42,31 @@ import java.util.Arrays;
  */
 public class Lexer {
 
-    protected final String  text;
-    protected int         pos;
-    protected int         mark;
+    protected final String text;
+    protected int          pos;
+    protected int          mark;
 
-    protected char        ch;
+    protected char         ch;
 
-    protected char[]      buf;
-    protected int         bufPos;
+    protected char[]       buf;
+    protected int          bufPos;
 
-    protected Token       token;
+    protected Token        token;
 
-    protected Keywords    keywods      = Keywords.DEFAULT_KEYWORDS;
+    protected Keywords     keywods      = Keywords.DEFAULT_KEYWORDS;
 
-    protected String      stringVal;
+    protected String       stringVal;
 
-    protected boolean     skipComment  = true;
+    protected boolean      skipComment  = true;
 
-    private SavePoint     savePoint    = null;
+    private SavePoint      savePoint    = null;
 
     /*
      * anti sql injection
      */
-    private boolean       allowComment = true;
+    private boolean        allowComment = true;
 
-    private int           varIndex     = -1;
+    private int            varIndex     = -1;
 
     public Lexer(String input){
         this(input, true);
@@ -78,7 +79,7 @@ public class Lexer {
 
         return text.charAt(index);
     }
-    
+
     public final String addSymbol() {
         return subString(mark, bufPos);
     }
@@ -86,7 +87,7 @@ public class Lexer {
     public final String subString(int offset, int count) {
         return text.substring(offset, offset + count);
     }
-    
+
     protected void initBuff(int size) {
         if (buf == null) {
             if (size < 32) {
@@ -94,7 +95,7 @@ public class Lexer {
             } else {
                 buf = new char[size + 32];
             }
-        } else if(buf.length < size) {
+        } else if (buf.length < size) {
             buf = Arrays.copyOf(buf, size);
         }
     }
@@ -116,6 +117,7 @@ public class Lexer {
     }
 
     private static class SavePoint {
+
         int   bp;
         int   sp;
         int   np;
@@ -187,32 +189,32 @@ public class Lexer {
     public String info() {
         return this.token + " " + this.stringVal();
     }
-    
+
     public final void nextTokenComma() {
         if (ch == ' ') {
             scanChar();
         }
-        
+
         if (ch == ',') {
             scanChar();
             token = COMMA;
             return;
         }
-        
+
         if (ch == ')') {
             scanChar();
             token = RPAREN;
             return;
         }
-        
+
         nextToken();
     }
-    
+
     public final void nextTokenLParen() {
         if (ch == ' ') {
             scanChar();
         }
-        
+
         if (ch == '(') {
             scanChar();
             token = LPAREN;
@@ -220,38 +222,38 @@ public class Lexer {
         }
         nextToken();
     }
-    
+
     public final void nextTokenValue() {
         if (ch == ' ') {
             scanChar();
         }
-        
+
         if (ch == '\'') {
             bufPos = 0;
             scanString();
             return;
         }
-        
+
         if (ch >= '0' && ch <= '9') {
             bufPos = 0;
             scanNumber();
             return;
         }
-        
+
         if (ch == '?') {
             scanChar();
             token = Token.QUES;
             return;
         }
-        
+
         if (isFirstIdentifierChar(ch) && ch != 'N') {
             scanIdentifier();
             return;
         }
-        
+
         nextToken();
     }
-    
+
     public final void nextToken() {
         bufPos = 0;
 
@@ -334,6 +336,9 @@ public class Lexer {
                     if (ch == '=') {
                         scanChar();
                         token = COLONEQ;
+                    } else if (ch == ':') {
+                        scanChar();
+                        token = COLONCOLON;
                     } else {
                         if (isDigit(ch)) {
                             unscan();
@@ -762,7 +767,6 @@ public class Lexer {
                 break;
             }
 
-
             bufPos++;
             continue;
         }

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

@@ -207,6 +207,7 @@ public enum Token {
     TILDE("~"), 
     QUES("?"), 
     COLON(":"), 
+    COLONCOLON(":"), 
     COLONEQ(":="), 
     EQEQ("=="), 
     LTEQ("<="), 

src/main/java/com/alibaba/druid/sql/visitor/SQLEvalVisitorUtils.java

@@ -56,16 +56,25 @@ import com.alibaba.druid.sql.dialect.oracle.visitor.OracleEvalVisitor;
 import com.alibaba.druid.sql.dialect.postgresql.visitor.PGEvalVisitor;
 import com.alibaba.druid.sql.dialect.sqlserver.visitor.SQLServerEvalVisitor;
 import com.alibaba.druid.sql.visitor.functions.Ascii;
+import com.alibaba.druid.sql.visitor.functions.Bin;
+import com.alibaba.druid.sql.visitor.functions.BitLength;
+import com.alibaba.druid.sql.visitor.functions.Char;
 import com.alibaba.druid.sql.visitor.functions.Concat;
+import com.alibaba.druid.sql.visitor.functions.Elt;
 import com.alibaba.druid.sql.visitor.functions.Function;
 import com.alibaba.druid.sql.visitor.functions.Hex;
+import com.alibaba.druid.sql.visitor.functions.Insert;
 import com.alibaba.druid.sql.visitor.functions.Instr;
 import com.alibaba.druid.sql.visitor.functions.Lcase;
 import com.alibaba.druid.sql.visitor.functions.Left;
 import com.alibaba.druid.sql.visitor.functions.Length;
+import com.alibaba.druid.sql.visitor.functions.Locate;
+import com.alibaba.druid.sql.visitor.functions.Lpad;
+import com.alibaba.druid.sql.visitor.functions.Ltrim;
 import com.alibaba.druid.sql.visitor.functions.Now;
 import com.alibaba.druid.sql.visitor.functions.Reverse;
 import com.alibaba.druid.sql.visitor.functions.Right;
+import com.alibaba.druid.sql.visitor.functions.Substring;
 import com.alibaba.druid.sql.visitor.functions.Trim;
 import com.alibaba.druid.sql.visitor.functions.Ucase;
 import com.alibaba.druid.sql.visitor.functions.Unhex;
@@ -149,13 +158,26 @@ public class SQLEvalVisitorUtils {
     static void registerBaseFunctions() {
         functions.put("now", Now.instance);
         functions.put("concat", Concat.instance);
+        functions.put("concat_ws", Concat.instance);
         functions.put("ascii", Ascii.instance);
+        functions.put("bin", Bin.instance);
+        functions.put("bit_length", BitLength.instance);
+        functions.put("insert", Insert.instance);
         functions.put("instr", Instr.instance);
+        functions.put("char", Char.instance);
+        functions.put("elt", Elt.instance);
         functions.put("left", Left.instance);
+        functions.put("locate", Locate.instance);
+        functions.put("lpad", Lpad.instance);
+        functions.put("ltrim", Ltrim.instance);
+        functions.put("mid", Substring.instance);
+        functions.put("substring", Substring.instance);
         functions.put("right", Right.instance);
         functions.put("reverse", Reverse.instance);
         functions.put("len", Length.instance);
         functions.put("length", Length.instance);
+        functions.put("char_length", Length.instance);
+        functions.put("character_length", Length.instance);
         functions.put("trim", Trim.instance);
         functions.put("ucase", Ucase.instance);
         functions.put("upper", Ucase.instance);
@@ -172,6 +194,7 @@ public class SQLEvalVisitorUtils {
 
         if (function != null) {
             Object result = function.eval(visitor, x);
+            
             if (result != SQLEvalVisitor.EVAL_ERROR) {
                 x.getAttributes().put(EVAL_VALUE, result);
             }
@@ -721,7 +744,7 @@ public class SQLEvalVisitorUtils {
             SQLExpr leftEvalExpr = (SQLExpr) left.getAttribute(EVAL_EXPR);
             SQLExpr rightEvalExpr = (SQLExpr) right.getAttribute(EVAL_EXPR);
 
-            if (leftEvalExpr.equals(rightEvalExpr)) {
+            if (leftEvalExpr != null && leftEvalExpr.equals(rightEvalExpr)) {
                 switch (x.getOperator()) {
                     case Like:
                     case Equality:

src/main/java/com/alibaba/druid/sql/visitor/SchemaStatVisitor.java

@@ -562,6 +562,10 @@ public class SchemaStatVisitor extends SQLASTVisitorAdapter {
     }
 
     public boolean visit(SQLSelectQueryBlock x) {
+        if (x.getFrom() == null) {
+            return false;
+        }
+        
         setMode(x, Mode.Select);
 
         if (x.getFrom() instanceof SQLSubqueryTableSource) {

src/main/java/com/alibaba/druid/sql/visitor/functions/Bin.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright 1999-2011 Alibaba Group Holding Ltd.
+ *
+ * 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.sql.visitor.functions;
+
+import static com.alibaba.druid.sql.visitor.SQLEvalVisitor.EVAL_VALUE;
+
+import com.alibaba.druid.sql.ast.SQLExpr;
+import com.alibaba.druid.sql.ast.expr.SQLMethodInvokeExpr;
+import com.alibaba.druid.sql.visitor.SQLEvalVisitor;
+
+public class Bin implements Function {
+
+    public final static Bin instance = new Bin();
+
+    public Object eval(SQLEvalVisitor visitor, SQLMethodInvokeExpr x) {
+        if (x.getParameters().size() != 1) {
+            return SQLEvalVisitor.EVAL_ERROR;
+        }
+
+        SQLExpr param0 = x.getParameters().get(0);
+        param0.accept(visitor);
+
+        Object param0Value = param0.getAttributes().get(EVAL_VALUE);
+        if (param0Value == null) {
+            return SQLEvalVisitor.EVAL_ERROR;
+        }
+
+        if (param0Value instanceof Number) {
+            long longValue = ((Number) param0Value).longValue();
+            String result = Long.toString(longValue, 2);
+            return result;
+        }
+        return SQLEvalVisitor.EVAL_ERROR;
+    }
+}

src/main/java/com/alibaba/druid/sql/visitor/functions/BitLength.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright 1999-2011 Alibaba Group Holding Ltd.
+ *
+ * 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.sql.visitor.functions;
+
+import static com.alibaba.druid.sql.visitor.SQLEvalVisitor.EVAL_VALUE;
+
+import com.alibaba.druid.sql.ast.SQLExpr;
+import com.alibaba.druid.sql.ast.expr.SQLMethodInvokeExpr;
+import com.alibaba.druid.sql.visitor.SQLEvalVisitor;
+
+public class BitLength implements Function {
+
+    public final static BitLength instance = new BitLength();
+
+    public Object eval(SQLEvalVisitor visitor, SQLMethodInvokeExpr x) {
+        if (x.getParameters().size() != 1) {
+            return SQLEvalVisitor.EVAL_ERROR;
+        }
+
+        SQLExpr param0 = x.getParameters().get(0);
+        param0.accept(visitor);
+
+        Object param0Value = param0.getAttributes().get(EVAL_VALUE);
+        if (param0Value == null) {
+            return SQLEvalVisitor.EVAL_ERROR;
+        }
+
+        if (param0Value instanceof String) {
+            return ((String) param0Value).getBytes().length * 8;
+        }
+        return SQLEvalVisitor.EVAL_ERROR;
+    }
+}

src/main/java/com/alibaba/druid/sql/visitor/functions/Char.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright 1999-2011 Alibaba Group Holding Ltd.
+ *
+ * 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.sql.visitor.functions;
+
+import static com.alibaba.druid.sql.visitor.SQLEvalVisitor.EVAL_VALUE;
+
+import java.math.BigDecimal;
+
+import com.alibaba.druid.sql.ast.SQLExpr;
+import com.alibaba.druid.sql.ast.expr.SQLMethodInvokeExpr;
+import com.alibaba.druid.sql.visitor.SQLEvalVisitor;
+
+public class Char implements Function {
+
+    public final static Char instance = new Char();
+
+    public Object eval(SQLEvalVisitor visitor, SQLMethodInvokeExpr x) {
+        if (x.getParameters().size() == 0) {
+            return SQLEvalVisitor.EVAL_ERROR;
+        }
+
+        StringBuffer buf = new StringBuffer(x.getParameters().size());
+        for (SQLExpr param : x.getParameters()) {
+            param.accept(visitor);
+
+            Object paramValue = param.getAttributes().get(EVAL_VALUE);
+
+            if (paramValue instanceof Number) {
+                int charCode = ((Number) paramValue).intValue();
+                buf.append((char) charCode);
+            } else if (paramValue instanceof String) {
+                int charCode = new BigDecimal((String)paramValue).intValue();
+                buf.append((char) charCode);
+            } else {
+                return SQLEvalVisitor.EVAL_ERROR;
+            }
+        }
+
+        return buf.toString();
+    }
+}

src/main/java/com/alibaba/druid/sql/visitor/functions/Elt.java

@@ -0,0 +1,53 @@
+/*
+ * Copyright 1999-2011 Alibaba Group Holding Ltd.
+ *
+ * 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.sql.visitor.functions;
+
+import static com.alibaba.druid.sql.visitor.SQLEvalVisitor.EVAL_VALUE;
+
+import com.alibaba.druid.sql.ast.SQLExpr;
+import com.alibaba.druid.sql.ast.expr.SQLMethodInvokeExpr;
+import com.alibaba.druid.sql.visitor.SQLEvalVisitor;
+
+public class Elt implements Function {
+
+    public final static Elt instance = new Elt();
+
+    public Object eval(SQLEvalVisitor visitor, SQLMethodInvokeExpr x) {
+        if (x.getParameters().size() <= 1) {
+            return SQLEvalVisitor.EVAL_ERROR;
+        }
+
+        SQLExpr param0 = x.getParameters().get(0);
+        param0.accept(visitor);
+
+        Object param0Value = param0.getAttributes().get(EVAL_VALUE);
+        int param0IntValue;
+        if (!(param0Value instanceof Number)) {
+            return SQLEvalVisitor.EVAL_ERROR;
+        }
+        param0IntValue = ((Number) param0Value).intValue();
+
+        if (param0IntValue >= x.getParameters().size()) {
+            return null;
+        }
+
+        SQLExpr item = x.getParameters().get(param0IntValue);
+        item.accept(visitor);
+
+        Object itemValue = item.getAttributes().get(EVAL_VALUE);
+        return itemValue;
+    }
+}

src/main/java/com/alibaba/druid/sql/visitor/functions/Hex.java

@@ -17,12 +17,11 @@ package com.alibaba.druid.sql.visitor.functions;
 
 import static com.alibaba.druid.sql.visitor.SQLEvalVisitor.EVAL_VALUE;
 
-import org.apache.xerces.impl.dv.util.HexBin;
-
 import com.alibaba.druid.sql.ast.SQLExpr;
 import com.alibaba.druid.sql.ast.expr.SQLMethodInvokeExpr;
 import com.alibaba.druid.sql.parser.ParserException;
 import com.alibaba.druid.sql.visitor.SQLEvalVisitor;
+import com.alibaba.druid.util.HexBin;
 
 public class Hex implements Function {
 

src/main/java/com/alibaba/druid/sql/visitor/functions/Insert.java

@@ -0,0 +1,83 @@
+/*
+ * Copyright 1999-2011 Alibaba Group Holding Ltd.
+ *
+ * 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.sql.visitor.functions;
+
+import static com.alibaba.druid.sql.visitor.SQLEvalVisitor.EVAL_VALUE;
+
+import com.alibaba.druid.sql.ast.SQLExpr;
+import com.alibaba.druid.sql.ast.expr.SQLMethodInvokeExpr;
+import com.alibaba.druid.sql.visitor.SQLEvalVisitor;
+
+public class Insert implements Function {
+
+    public final static Insert instance = new Insert();
+
+    public Object eval(SQLEvalVisitor visitor, SQLMethodInvokeExpr x) {
+        if (x.getParameters().size() != 4) {
+            return SQLEvalVisitor.EVAL_ERROR;
+        }
+
+        SQLExpr param0 = x.getParameters().get(0);
+        SQLExpr param1 = x.getParameters().get(1);
+        SQLExpr param2 = x.getParameters().get(2);
+        SQLExpr param3 = x.getParameters().get(3);
+        param0.accept(visitor);
+        param1.accept(visitor);
+        param2.accept(visitor);
+        param3.accept(visitor);
+
+        Object param0Value = param0.getAttributes().get(EVAL_VALUE);
+        Object param1Value = param1.getAttributes().get(EVAL_VALUE);
+        Object param2Value = param2.getAttributes().get(EVAL_VALUE);
+        Object param3Value = param3.getAttributes().get(EVAL_VALUE);
+
+        if (!(param0Value instanceof String)) {
+            return SQLEvalVisitor.EVAL_ERROR;
+        }
+        if (!(param1Value instanceof Number)) {
+            return SQLEvalVisitor.EVAL_ERROR;
+        }
+        if (!(param2Value instanceof Number)) {
+            return SQLEvalVisitor.EVAL_ERROR;
+        }
+        if (!(param3Value instanceof String)) {
+            return SQLEvalVisitor.EVAL_ERROR;
+        }
+
+        String str = (String) param0Value;
+        int pos = ((Number) param1Value).intValue();
+        int len = ((Number) param2Value).intValue();
+        String newstr = (String) param3Value;
+        
+        if (pos <= 0) {
+            return str;
+        }
+        
+        if (pos == 1) {
+            if (len > str.length()) {
+                return newstr;
+            }
+            return newstr + str.substring(len);
+        }
+        
+        String first = str.substring(0, pos - 1);
+        if (pos + len - 1 > str.length()) {
+            return first + newstr;
+        }
+        
+        return first + newstr + str.substring(pos + len - 1);
+    }
+}

src/main/java/com/alibaba/druid/sql/visitor/functions/Locate.java

@@ -0,0 +1,68 @@
+/*
+ * Copyright 1999-2011 Alibaba Group Holding Ltd.
+ *
+ * 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.sql.visitor.functions;
+
+import static com.alibaba.druid.sql.visitor.SQLEvalVisitor.EVAL_VALUE;
+
+import java.util.List;
+
+import com.alibaba.druid.sql.ast.SQLExpr;
+import com.alibaba.druid.sql.ast.expr.SQLMethodInvokeExpr;
+import com.alibaba.druid.sql.visitor.SQLEvalVisitor;
+
+public class Locate implements Function {
+
+    public final static Locate instance = new Locate();
+
+    public Object eval(SQLEvalVisitor visitor, SQLMethodInvokeExpr x) {
+        List<SQLExpr> params = x.getParameters();
+        int paramSize = params.size();
+        if (paramSize != 2 && paramSize != 3) {
+            return SQLEvalVisitor.EVAL_ERROR;
+        }
+
+        SQLExpr param0 = params.get(0);
+        SQLExpr param1 = params.get(1);
+        SQLExpr param2 = null;
+
+        param0.accept(visitor);
+        param1.accept(visitor);
+        if (paramSize == 3) {
+            param2 = params.get(2);
+            param2.accept(visitor);
+        }
+
+        Object param0Value = param0.getAttributes().get(EVAL_VALUE);
+        Object param1Value = param1.getAttributes().get(EVAL_VALUE);
+        if (param0Value == null || param1Value == null) {
+            return SQLEvalVisitor.EVAL_ERROR;
+        }
+
+        String strValue0 = param0Value.toString();
+        String strValue1 = param1Value.toString();
+
+        if (paramSize == 2) {
+            int result = strValue1.indexOf(strValue0) + 1;
+            return result;
+        }
+        
+        Object param2Value = param2.getAttributes().get(EVAL_VALUE);
+        int start = ((Number) param2Value).intValue();
+        
+        int result = strValue1.indexOf(strValue0, start + 1) + 1;
+        return result;
+    }
+}

src/main/java/com/alibaba/druid/sql/visitor/functions/Lpad.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright 1999-2011 Alibaba Group Holding Ltd.
+ *
+ * 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.sql.visitor.functions;
+
+import static com.alibaba.druid.sql.visitor.SQLEvalVisitor.EVAL_VALUE;
+
+import java.util.List;
+
+import com.alibaba.druid.sql.ast.SQLExpr;
+import com.alibaba.druid.sql.ast.expr.SQLMethodInvokeExpr;
+import com.alibaba.druid.sql.visitor.SQLEvalVisitor;
+
+public class Lpad implements Function {
+
+    public final static Lpad instance = new Lpad();
+
+    public Object eval(SQLEvalVisitor visitor, SQLMethodInvokeExpr x) {
+        List<SQLExpr> params = x.getParameters();
+        int paramSize = params.size();
+        if (paramSize != 3) {
+            return SQLEvalVisitor.EVAL_ERROR;
+        }
+
+        SQLExpr param0 = params.get(0);
+        SQLExpr param1 = params.get(1);
+        SQLExpr param2 = params.get(2);
+
+        param0.accept(visitor);
+        param1.accept(visitor);
+        param2.accept(visitor);
+
+        Object param0Value = param0.getAttributes().get(EVAL_VALUE);
+        Object param1Value = param1.getAttributes().get(EVAL_VALUE);
+        Object param2Value = param2.getAttributes().get(EVAL_VALUE);
+        if (param0Value == null || param1Value == null || param2Value == null) {
+            return SQLEvalVisitor.EVAL_ERROR;
+        }
+
+        String strValue0 = param0Value.toString();
+        int len = ((Number) param1Value).intValue();
+        String strValue1 = param2Value.toString();
+        
+        String result = strValue0;
+        if (result.length() > len) {
+            return result.substring(0, len);
+        }
+        
+        while (result.length() < len) {
+            result = strValue1 + result;
+        }
+
+        return result;
+    }
+}

src/main/java/com/alibaba/druid/sql/visitor/functions/Ltrim.java

@@ -0,0 +1,57 @@
+/*
+ * Copyright 1999-2011 Alibaba Group Holding Ltd.
+ *
+ * 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.sql.visitor.functions;
+
+import static com.alibaba.druid.sql.visitor.SQLEvalVisitor.EVAL_VALUE;
+
+import com.alibaba.druid.sql.ast.SQLExpr;
+import com.alibaba.druid.sql.ast.expr.SQLMethodInvokeExpr;
+import com.alibaba.druid.sql.visitor.SQLEvalVisitor;
+
+public class Ltrim implements Function {
+
+    public final static Ltrim instance = new Ltrim();
+
+    public Object eval(SQLEvalVisitor visitor, SQLMethodInvokeExpr x) {
+        if (x.getParameters().size() != 1) {
+            return SQLEvalVisitor.EVAL_ERROR;
+        }
+
+        SQLExpr param0 = x.getParameters().get(0);
+        param0.accept(visitor);
+
+        Object param0Value = param0.getAttributes().get(EVAL_VALUE);
+        if (param0Value == null) {
+            return SQLEvalVisitor.EVAL_ERROR;
+        }
+
+        String strValue = param0Value.toString();
+        
+        int index = -1;
+        for (int i = 0; i < strValue.length(); ++i) {
+            if (!Character.isWhitespace(strValue.charAt(i))) {
+                index = i;
+                break;
+            }
+        }
+        
+        if (index <= 0) {
+            return strValue;
+        } else {
+            return strValue.substring(index);
+        }
+    }
+}

src/main/java/com/alibaba/druid/sql/visitor/functions/Substring.java

@@ -0,0 +1,80 @@
+/*
+ * Copyright 1999-2011 Alibaba Group Holding Ltd.
+ *
+ * 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.sql.visitor.functions;
+
+import static com.alibaba.druid.sql.visitor.SQLEvalVisitor.EVAL_VALUE;
+
+import java.util.List;
+
+import com.alibaba.druid.sql.ast.SQLExpr;
+import com.alibaba.druid.sql.ast.expr.SQLMethodInvokeExpr;
+import com.alibaba.druid.sql.visitor.SQLEvalVisitor;
+
+public class Substring implements Function {
+
+    public final static Substring instance = new Substring();
+
+    public Object eval(SQLEvalVisitor visitor, SQLMethodInvokeExpr x) {
+        List<SQLExpr> params = x.getParameters();
+        int paramSize = params.size();
+        if (paramSize != 2 && paramSize != 3) {
+            return SQLEvalVisitor.EVAL_ERROR;
+        }
+
+        SQLExpr param0 = params.get(0);
+        SQLExpr param1 = params.get(1);
+        param0.accept(visitor);
+        param1.accept(visitor);
+
+        Object param0Value = param0.getAttributes().get(EVAL_VALUE);
+        Object param1Value = param1.getAttributes().get(EVAL_VALUE);
+        if (param0Value == null || param1Value == null) {
+            return SQLEvalVisitor.EVAL_ERROR;
+        }
+
+        String str = param0Value.toString();
+        int index = ((Number) param1Value).intValue();
+
+        if (paramSize == 2) {
+
+            if (index < 0) {
+                int lastIndex = str.length() + index ;
+                return str.substring(lastIndex);
+            }
+
+            return str.substring(index - 1);
+        }
+
+        SQLExpr param2 = params.get(2);
+        param2.accept(visitor);
+        Object param2Value = param2.getAttributes().get(EVAL_VALUE);
+        if (param2Value == null) {
+            return SQLEvalVisitor.EVAL_ERROR;
+        }
+
+        int len = ((Number) param2Value).intValue();
+        
+        String result;
+        if (index < 0) {
+            int lastIndex = str.length() + index ;
+            result = str.substring(lastIndex);
+        } else {
+            result = str.substring(index - 1);
+        }
+        
+        return result.substring(0, len);
+    }
+}

src/main/java/com/alibaba/druid/sql/visitor/functions/Unhex.java

@@ -15,17 +15,15 @@
  */
 package com.alibaba.druid.sql.visitor.functions;
 
-import static com.alibaba.druid.sql.visitor.SQLEvalVisitor.EVAL_VALUE;
 import static com.alibaba.druid.sql.visitor.SQLEvalVisitor.EVAL_EXPR;
+import static com.alibaba.druid.sql.visitor.SQLEvalVisitor.EVAL_VALUE;
 
 import java.io.UnsupportedEncodingException;
 
-import org.apache.xerces.impl.dv.util.HexBin;
-
 import com.alibaba.druid.sql.ast.SQLExpr;
 import com.alibaba.druid.sql.ast.expr.SQLMethodInvokeExpr;
-import com.alibaba.druid.sql.parser.ParserException;
 import com.alibaba.druid.sql.visitor.SQLEvalVisitor;
+import com.alibaba.druid.util.HexBin;
 
 public class Unhex implements Function {
 
@@ -33,7 +31,7 @@ public class Unhex implements Function {
 
     public Object eval(SQLEvalVisitor visitor, SQLMethodInvokeExpr x) {
         if (x.getParameters().size() != 1) {
-            throw new ParserException("argument's != 1, " + x.getParameters().size());
+            return SQLEvalVisitor.EVAL_ERROR;
         }
 
         SQLExpr param0 = x.getParameters().get(0);