improved sql parser.

src/main/java/com/alibaba/druid/sql/ast/statement/SQLCharacterDataType.java

@@ -17,6 +17,8 @@ package com.alibaba.druid.sql.ast.statement;
 
 import com.alibaba.druid.sql.ast.SQLCommentHint;
 import com.alibaba.druid.sql.ast.SQLDataTypeImpl;
+import com.alibaba.druid.sql.ast.SQLExpr;
+import com.alibaba.druid.sql.ast.expr.SQLIntegerExpr;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
 import java.util.List;
@@ -78,6 +80,17 @@ public class SQLCharacterDataType extends SQLDataTypeImpl {
         this.hints = hints;
     }
 
+    public int getLength() {
+        if (this.arguments.size() == 1) {
+            SQLExpr arg = this.arguments.get(0);
+            if (arg instanceof SQLIntegerExpr) {
+                return ((SQLIntegerExpr) arg).getNumber().intValue();
+            }
+        }
+
+        return -1;
+    }
+
     @Override
     protected void accept0(SQLASTVisitor visitor) {
         if (visitor.visit(this)) {

src/main/java/com/alibaba/druid/sql/ast/statement/SQLCreateTableStatement.java

@@ -20,6 +20,7 @@ import java.util.HashMap;
 import java.util.List;
 
 import com.alibaba.druid.sql.SQLUtils;
+import com.alibaba.druid.sql.ast.SQLDataType;
 import com.alibaba.druid.sql.ast.SQLExpr;
 import com.alibaba.druid.sql.ast.SQLName;
 import com.alibaba.druid.sql.ast.SQLStatementImpl;
@@ -27,6 +28,7 @@ import com.alibaba.druid.sql.ast.expr.SQLIdentifierExpr;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlTableIndex;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 import com.alibaba.druid.stat.TableStat;
+import com.alibaba.druid.util.lang.Consumer;
 
 public class SQLCreateTableStatement extends SQLStatementImpl implements SQLDDLStatement {
 
@@ -213,4 +215,16 @@ public class SQLCreateTableStatement extends SQLStatementImpl implements SQLDDLS
 
         return null;
     }
+
+    public void forEachColumn(Consumer<SQLColumnDefinition> columnConsumer) {
+        if (columnConsumer == null) {
+            return;
+        }
+
+        for (SQLTableElement element : this.tableElementList) {
+            if (element instanceof SQLColumnDefinition) {
+                columnConsumer.accept((SQLColumnDefinition) element);
+            }
+        }
+    }
 }

src/main/java/com/alibaba/druid/sql/ast/statement/SQLSelectItem.java

@@ -157,4 +157,28 @@ public class SQLSelectItem extends SQLObjectImpl implements SQLReplaceable {
 
         return false;
     }
+
+    public boolean match(String alias) {
+        if (alias == null) {
+            return false;
+        }
+
+        String alias_normalized = SQLUtils.normalize(alias);
+
+        if (alias_normalized.equalsIgnoreCase(this.alias)) {
+            return true;
+        }
+
+        if (expr instanceof SQLIdentifierExpr) {
+            String ident = ((SQLIdentifierExpr) expr).getName();
+            return alias_normalized.equalsIgnoreCase(SQLUtils.normalize(ident));
+        }
+
+        if (expr instanceof SQLPropertyExpr) {
+            String ident = ((SQLPropertyExpr) expr).getName();
+            return alias_normalized.equalsIgnoreCase(SQLUtils.normalize(ident));
+        }
+
+        return false;
+    }
 }

src/main/java/com/alibaba/druid/sql/ast/statement/SQLSelectQueryBlock.java

@@ -18,7 +18,9 @@ package com.alibaba.druid.sql.ast.statement;
 import java.util.ArrayList;
 import java.util.List;
 
+import com.alibaba.druid.sql.SQLUtils;
 import com.alibaba.druid.sql.ast.*;
+import com.alibaba.druid.sql.ast.expr.SQLIdentifierExpr;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
 public class SQLSelectQueryBlock extends SQLObjectImpl implements SQLSelectQuery, SQLReplaceable {
@@ -421,4 +423,20 @@ public class SQLSelectQueryBlock extends SQLObjectImpl implements SQLSelectQuery
         }
         return false;
     }
+
+    public SQLSelectItem findSelectItem(String ident) {
+        if (ident == null) {
+            return null;
+        }
+
+        String ident_normalized = SQLUtils.normalize(ident);
+
+        for (SQLSelectItem item : this.selectList) {
+            if (item.match(ident_normalized)) {
+                return item;
+            }
+        }
+
+        return null;
+    }
 }