mysql parser refactor

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

@@ -0,0 +1,28 @@
+package com.alibaba.druid.sql.ast.statement;
+
+import com.alibaba.druid.sql.ast.SQLName;
+import com.alibaba.druid.sql.ast.SQLObjectImpl;
+import com.alibaba.druid.sql.visitor.SQLASTVisitor;
+
+public class SQLAlterTableDropColumnItem extends SQLObjectImpl implements SQLAlterTableItem {
+
+    private static final long serialVersionUID = 1L;
+    private SQLName           columnName;
+
+    @Override
+    protected void accept0(SQLASTVisitor visitor) {
+        if (visitor.visit(this)) {
+            acceptChild(visitor, columnName);
+        }
+        visitor.endVisit(this);
+    }
+
+    public SQLName getColumnName() {
+        return columnName;
+    }
+
+    public void setColumnName(SQLName columnName) {
+        this.columnName = columnName;
+    }
+
+}