bug fixed for db2 sql parser. for issue #2357

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

@@ -17,7 +17,10 @@ package com.alibaba.druid.sql.dialect.db2.parser;
 
 import java.util.List;
 
+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.*;
 
@@ -54,4 +57,41 @@ public class DB2StatementParser extends SQLStatementParser {
     public SQLCreateTableParser getSQLCreateTableParser() {
         return new DB2CreateTableParser(this.exprParser);
     }
+
+    protected SQLAlterTableAlterColumn parseAlterColumn() {
+        if (lexer.token() == Token.COLUMN) {
+            lexer.nextToken();
+        }
+
+        SQLColumnDefinition column = this.exprParser.parseColumn();
+
+        SQLAlterTableAlterColumn alterColumn = new SQLAlterTableAlterColumn();
+        alterColumn.setColumn(column);
+
+        if (column.getDataType() == null && column.getConstraints().size() == 0) {
+            if (lexer.token() == Token.SET) {
+                lexer.nextToken();
+                if (lexer.token() == Token.NOT) {
+                    lexer.nextToken();
+                    accept(Token.NULL);
+                    alterColumn.setSetNotNull(true);
+                } else {
+                    accept(Token.DEFAULT);
+                    SQLExpr defaultValue = this.exprParser.expr();
+                    alterColumn.setSetDefault(defaultValue);
+                }
+            } else if (lexer.token() == Token.DROP) {
+                lexer.nextToken();
+                if (lexer.token() == Token.NOT) {
+                    lexer.nextToken();
+                    accept(Token.NULL);
+                    alterColumn.setDropNotNull(true);
+                } else {
+                    accept(Token.DEFAULT);
+                    alterColumn.setDropDefault(true);
+                }
+            }
+        }
+        return alterColumn;
+    }
 }

src/test/java/com/alibaba/druid/bvt/sql/db2/DB2AlterTableTest_1_setNotNull.java

@@ -0,0 +1,47 @@
+/*
+ * 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.util.JdbcConstants;
+import junit.framework.TestCase;
+import org.junit.Assert;
+
+public class DB2AlterTableTest_1_setNotNull extends TestCase {
+
+    public void test_alter_constraint() throws Exception {
+        String sql = "alter table T_ORG alter column ORG_NAME set not null";
+        SQLStatement stmt = SQLUtils.parseStatements(sql, JdbcConstants.DB2).get(0);
+
+        OracleSchemaStatVisitor visitor = new OracleSchemaStatVisitor();
+        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());
+
+        String output = SQLUtils.toSQLString(stmt, JdbcConstants.DB2);
+        assertEquals("ALTER TABLE T_ORG\n" +
+                "\tALTER COLUMN ORG_NAME SET NOT NULL", output);
+
+        assertEquals(1, visitor.getTables().size());
+        assertEquals(1, visitor.getColumns().size());
+    }
+
+}