improved postgresql sql parser. support if not exists.

src/main/java/com/alibaba/druid/sql/dialect/hive/parser/HiveCreateTableParser.java

@@ -1,3 +1,18 @@
+/*
+ * Copyright 1999-2017 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.dialect.hive.parser;
 
 import com.alibaba.druid.sql.ast.SQLName;

src/main/java/com/alibaba/druid/sql/dialect/hive/stmt/HiveCreateTableStatement.java

@@ -1,7 +1,20 @@
+/*
+ * Copyright 1999-2017 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.dialect.hive.stmt;
 
-import com.alibaba.druid.sql.ast.SQLName;
-import com.alibaba.druid.sql.ast.expr.SQLIdentifierExpr;
 import com.alibaba.druid.sql.ast.statement.SQLCreateTableStatement;
 import com.alibaba.druid.util.JdbcConstants;
 

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

@@ -19,6 +19,7 @@ import java.util.List;
 
 import com.alibaba.druid.sql.ast.SQLName;
 import com.alibaba.druid.sql.ast.statement.*;
+import com.alibaba.druid.util.FnvHash;
 import com.alibaba.druid.util.JdbcConstants;
 
 public class SQLCreateTableParser extends SQLDDLParser {
@@ -77,6 +78,14 @@ public class SQLCreateTableParser extends SQLDDLParser {
 
         accept(Token.TABLE);
 
+        if (lexer.token() == Token.IF) {
+            lexer.nextToken();
+            accept(Token.NOT);
+            accept(Token.EXISTS);
+
+            createTable.setIfNotExiists(true);
+        }
+
         createTable.setName(this.exprParser.name());
 
         if (lexer.token == Token.LPAREN) {

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

@@ -1309,6 +1309,7 @@ public class SQLExprParser extends SQLParser {
                 case ORDER:
                 case DO:
                 case JOIN:
+                case TYPE:
                     identName = lexer.stringVal();
                     lexer.nextToken();
                     break;

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

@@ -2526,6 +2526,10 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
         }
         print0(ucase ? "TABLE " : "table ");
 
+        if (x.isIfNotExiists()) {
+            print0(ucase ? "IF NOT EXISTS " : "if not exists ");
+        }
+
         printTableSourceExpr(x.getName());
 
         printTableElements(x.getTableElementList());