在MySQL中，请看下表定义:
CREATE TABLE table1 (
column1 INT,
column2 INT,
column3 INT,
column4 INT
)
在上表中的 column2 后添加列 "column2a"，以下哪种语法是正确的？( )
ALTER TABLE table1 ADD column2a INT AFTER column2
MODIFY TABLE table1 ADD column2a AFTER column2
INSERT INTO table1 column2a AS INT AFTER column2
ALTER TABLE table1 INSERT column2a INT AFTER column2
CHANGE TABLE table1 INSERT column2a BEFORE column3
Columns are always added after the last column
