更改多列的列类型

Question

I'm trying to change type of multiple columns in a one table to varchar(50) (in a single SQL query). Can you please tell me what am I doing wrong, and why this query shows error.

ALTER TABLE 'my_table_name' 
    ALTER COLUMN 'col1' varchar(50), 
    ALTER COLUMN 'col2' varchar(50), 
    ALTER COLUMN 'col3' varchar(50)

Thank you!

Answer 1

Remove the single quotation marks and use MODIFY not CHANGE COLUMN

ALTER TABLE my_table_name 
    MODIFY col1 varchar(50), 
    MODIFY col2 varchar(50), 
    MODIFY col3 varchar(50)