improved db2 parser. for issue #2548

src/main/java/com/alibaba/druid/sql/ast/SQLStatement.java

@@ -18,9 +18,10 @@ package com.alibaba.druid.sql.ast;
 import java.util.List;
 
 public interface SQLStatement extends SQLObject {
-    String       getDbType();
-    boolean      isAfterSemi();
-    void         setAfterSemi(boolean afterSemi);
-    SQLStatement clone();
-     List<SQLObject> getChildren();
+    String          getDbType();
+    boolean         isAfterSemi();
+    void            setAfterSemi(boolean afterSemi);
+    SQLStatement    clone();
+    List<SQLObject> getChildren();
+    String          toLowerCaseString();
 }

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

@@ -16,6 +16,7 @@
 
 package com.alibaba.druid.sql.ast.statement;
 
+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.SQLObjectImpl;
@@ -23,16 +24,12 @@ import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
 public class SQLAlterTableAlterColumn extends SQLObjectImpl implements SQLAlterTableItem {
     private SQLName             originColumn;
-
     private SQLColumnDefinition column;
-
     private boolean             setNotNull;
-
     private boolean             dropNotNull;
-
     private SQLExpr             setDefault;
-
     private boolean             dropDefault;
+    private SQLDataType         dataType;
 
     @Override
     protected void accept0(SQLASTVisitor visitor) {
@@ -87,10 +84,21 @@ public class SQLAlterTableAlterColumn extends SQLObjectImpl implements SQLAlterT
         return originColumn;
     }
 
-    public void setOriginColumn(SQLName originColumn) {
-        if (originColumn != null) {
-            originColumn.setParent(this);
+    public void setOriginColumn(SQLName x) {
+        if (x != null) {
+            x.setParent(this);
         }
-        this.originColumn = originColumn;
+        this.originColumn = x;
+    }
+
+    public SQLDataType getDataType() {
+        return dataType;
+    }
+
+    public void setDataType(SQLDataType x) {
+        if (x != null) {
+            x.setParent(this);
+        }
+        this.dataType = x;
     }
 }

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

@@ -194,4 +194,8 @@ public class SQLInsertStatement extends SQLInsertInto implements SQLStatement {
     public String toString() {
         return SQLUtils.toSQLString(this, dbType);
     }
+
+    public String toLowerCaseString() {
+        return SQLUtils.toSQLString(this, dbType, SQLUtils.DEFAULT_LCASE_FORMAT_OPTION);
+    }
 }

src/main/java/com/alibaba/druid/sql/dialect/db2/parser/DB2StatementParser.java

@@ -17,12 +17,14 @@ package com.alibaba.druid.sql.dialect.db2.parser;
 
 import java.util.List;
 
+import com.alibaba.druid.sql.ast.SQLDataType;
 import com.alibaba.druid.sql.ast.SQLExpr;
 import com.alibaba.druid.sql.ast.SQLStatement;
 import com.alibaba.druid.sql.ast.statement.SQLAlterTableAlterColumn;
 import com.alibaba.druid.sql.ast.statement.SQLColumnDefinition;
 import com.alibaba.druid.sql.dialect.db2.ast.stmt.DB2ValuesStatement;
 import com.alibaba.druid.sql.parser.*;
+import com.alibaba.druid.util.FnvHash;
 
 
 public class DB2StatementParser extends SQLStatementParser {
@@ -75,10 +77,17 @@ public class DB2StatementParser extends SQLStatementParser {
                     lexer.nextToken();
                     accept(Token.NULL);
                     alterColumn.setSetNotNull(true);
-                } else {
-                    accept(Token.DEFAULT);
+                } else if (lexer.token() == Token.DEFAULT) {
+                    lexer.nextToken();
                     SQLExpr defaultValue = this.exprParser.expr();
                     alterColumn.setSetDefault(defaultValue);
+                } else if (lexer.identifierEquals(FnvHash.Constants.DATA)) {
+                    lexer.nextToken();
+                    acceptIdentifier("TYPE");
+                    SQLDataType dataType = this.exprParser.parseDataType();
+                    alterColumn.setDataType(dataType);
+                } else {
+                    throw new ParserException("TODO : " + lexer.info());
                 }
             } else if (lexer.token() == Token.DROP) {
                 lexer.nextToken();

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

@@ -3817,13 +3817,22 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
         if (x.isSetNotNull()) { // postgresql
             print0(ucase ? " SET NOT NULL" : " set not null");
         }
+
         if (x.isDropNotNull()) { // postgresql
             print0(ucase ? " DROP NOT NULL" : " drop not null");
         }
+
         if (x.getSetDefault() != null) { // postgresql
             print0(ucase ? " SET DEFAULT " : " set default ");
             x.getSetDefault().accept(this);
         }
+
+        final SQLDataType dataType = x.getDataType();
+        if (dataType != null) {
+            print0(ucase ? " SET DATA TYPE " : " set data type ");
+            dataType.accept(this);
+        }
+
         if (x.isDropDefault()) { // postgresql
             print0(ucase ? " DROP DEFAULT" : " drop default");
         }

src/test/java/com/alibaba/druid/bvt/sql/db2/DB2AlterTableTest_2.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright 1999-2018 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.bvt.sql.db2;
+
+import com.alibaba.druid.sql.SQLUtils;
+import com.alibaba.druid.sql.ast.SQLStatement;
+import com.alibaba.druid.sql.dialect.oracle.visitor.OracleSchemaStatVisitor;
+import com.alibaba.druid.sql.visitor.SchemaStatVisitor;
+import com.alibaba.druid.util.JdbcConstants;
+import junit.framework.TestCase;
+
+public class DB2AlterTableTest_2 extends TestCase {
+
+    public void test_alter_constraint() throws Exception {
+        String sql = "alter table audit.SQLHIS alter column  EXPLAINMSG set data type VARCHAR(255)";
+        SQLStatement stmt = SQLUtils.parseStatements(sql, JdbcConstants.DB2).get(0);
+
+        SchemaStatVisitor visitor = SQLUtils.createSchemaStatVisitor(JdbcConstants.DB2);
+        stmt.accept(visitor);
+
+        System.out.println("Tables : " + visitor.getTables());
+        System.out.println("fields : " + visitor.getColumns());
+        System.out.println("coditions : " + visitor.getConditions());
+        System.out.println("orderBy : " + visitor.getOrderByColumns());
+
+        assertEquals("ALTER TABLE audit.SQLHIS\n" +
+                "\tALTER COLUMN EXPLAINMSG SET DATA TYPE VARCHAR(255)", stmt.toString());
+
+        assertEquals("alter table audit.SQLHIS\n" +
+                "\talter column EXPLAINMSG set data type VARCHAR(255)", stmt.toLowerCaseString());
+
+        assertEquals(1, visitor.getTables().size());
+        assertEquals(1, visitor.getColumns().size());
+    }
+
+}