sql parser refactor

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

@@ -5,7 +5,7 @@ import java.util.List;
 
 import com.alibaba.druid.sql.ast.SQLStatementImpl;
 
-public class SQLAlterTableStatement extends SQLStatementImpl {
+public class SQLAlterTableStatement extends SQLStatementImpl implements SQLDDLStatement {
 
     private static final long       serialVersionUID = 1L;
 

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

@@ -23,7 +23,7 @@ import com.alibaba.druid.sql.ast.SQLStatementImpl;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
 @SuppressWarnings("serial")
-public class SQLCreateTableStatement extends SQLStatementImpl {
+public class SQLCreateTableStatement extends SQLStatementImpl implements SQLDDLStatement {
 
     protected Type                  type;
     protected SQLExprTableSource    tableSource;

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

@@ -23,7 +23,7 @@ import com.alibaba.druid.sql.ast.SQLName;
 import com.alibaba.druid.sql.ast.SQLStatementImpl;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
-public class SQLCreateViewStatement extends SQLStatementImpl {
+public class SQLCreateViewStatement extends SQLStatementImpl implements SQLDDLStatement {
 
     private static final long     serialVersionUID = 1L;
     protected SQLName             name;

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

@@ -0,0 +1,8 @@
+package com.alibaba.druid.sql.ast.statement;
+
+import com.alibaba.druid.sql.ast.SQLStatement;
+
+
+public interface SQLDDLStatement extends SQLStatement {
+
+}

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

@@ -22,7 +22,7 @@ import com.alibaba.druid.sql.ast.SQLName;
 import com.alibaba.druid.sql.ast.SQLStatementImpl;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
-public class SQLDropTableStatement extends SQLStatementImpl {
+public class SQLDropTableStatement extends SQLStatementImpl implements SQLDDLStatement {
 
     private static final long          serialVersionUID = 1L;
 

src/main/java/com/alibaba/druid/sql/dialect/oracle/ast/stmt/OracleAlterTableStatement.java

@@ -6,7 +6,7 @@ import com.alibaba.druid.sql.ast.statement.SQLExprTableSource;
 import com.alibaba.druid.sql.dialect.oracle.visitor.OracleASTVisitor;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
-public class OracleAlterTableStatement extends SQLAlterTableStatement implements OracleStatement {
+public class OracleAlterTableStatement extends SQLAlterTableStatement implements OracleDDLStatement {
 
     private static final long  serialVersionUID        = 1L;
 

src/main/java/com/alibaba/druid/sql/dialect/oracle/ast/stmt/OracleCreateTableStatement.java

@@ -9,7 +9,7 @@ import com.alibaba.druid.sql.dialect.oracle.ast.clause.OracleStorageClause;
 import com.alibaba.druid.sql.dialect.oracle.visitor.OracleASTVisitor;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
-public class OracleCreateTableStatement extends SQLCreateTableStatement implements OracleStatement {
+public class OracleCreateTableStatement extends SQLCreateTableStatement implements OracleDDLStatement {
 
     private static final long        serialVersionUID  = 1L;
 

src/main/java/com/alibaba/druid/sql/dialect/oracle/ast/stmt/OracleDDLStatement.java

@@ -0,0 +1,8 @@
+package com.alibaba.druid.sql.dialect.oracle.ast.stmt;
+
+import com.alibaba.druid.sql.ast.statement.SQLDDLStatement;
+
+
+public interface OracleDDLStatement extends SQLDDLStatement, OracleStatement {
+
+}