sql parser refactor

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

@@ -0,0 +1,31 @@
+package com.alibaba.druid.sql.ast.statement;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import com.alibaba.druid.sql.ast.SQLObjectImpl;
+import com.alibaba.druid.sql.visitor.SQLASTVisitor;
+
+public class SQLAlterTableAddColumn extends SQLObjectImpl implements SQLAlterTableItem {
+
+    private static final long         serialVersionUID = 1L;
+
+    private List<SQLColumnDefinition> columns          = new ArrayList<SQLColumnDefinition>();
+
+    @Override
+    protected void accept0(SQLASTVisitor visitor) {
+        if (visitor.visit(this)) {
+            acceptChild(visitor, columns);
+        }
+        visitor.endVisit(this);
+    }
+
+    public List<SQLColumnDefinition> getColumns() {
+        return columns;
+    }
+
+    public void setColumns(List<SQLColumnDefinition> columns) {
+        this.columns = columns;
+    }
+
+}

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

@@ -3,6 +3,7 @@ package com.alibaba.druid.sql.ast.statement;
 import java.util.ArrayList;
 import java.util.List;
 
+import com.alibaba.druid.sql.ast.SQLName;
 import com.alibaba.druid.sql.ast.SQLStatementImpl;
 
 public class SQLAlterTableStatement extends SQLStatementImpl implements SQLDDLStatement {
@@ -28,4 +29,14 @@ public class SQLAlterTableStatement extends SQLStatementImpl implements SQLDDLSt
         this.tableSource = tableSource;
     }
 
+    public SQLName getName() {
+        if (getTableSource() == null) {
+            return null;
+        }
+        return (SQLName) getTableSource().getExpr();
+    }
+
+    public void setName(SQLName name) {
+        this.setTableSource(new SQLExprTableSource(name));
+    }
 }