Modify column Vs change column

Question

I know, we can not rename a column using modify column syntax,but can change column syntax.

My question is: what is the main usage of

Answer 1

The difference is whether you want to change the column name, column definition or both.

CHANGE

Can rename a column or change its definition, or both.

ALTER TABLE t1 CHANGE a b BIGINT NOT NULL

MODIFY

Can change a column definition but not its name

ALTER TABLE t1 MODIFY b INT NOT NULL

RENAME COLUMN

Can change a column name but not its definition.

ALTER TABLE t1 RENAME COLUMN b TO a

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You can check the docs for the complete explanation.

Answer 2

That is the same. It was done to support another syntax (Oracle ALTER TABLE as I know). You can use both of them.

Note: ALTER TABLE CHANGE old_col_name new_col_name syntax allows renaming column using one command.

Answer 3

I found one difference after more than an hour of effort in trying to make a non auto_increment column into auto_increment statement: alter table doctor_experience modify column id int(11) unsigned auto_increment works, but statment: alter table doctor_experience change column id id int(11) unsigned auto_increment will report an error.

Answer 4

CHANGE COLUMN If you have already created your MySQL database, and decide after the fact that one of your columns is named incorrectly, you don't need to remove it and make a replacement, you can simply rename it using change column.

ALTER TABLE MyTable CHANGE COLUMN foo bar VARCHAR(32) NOT NULL FIRST;

MODIFY COLUMN This command does everything CHANGE COLUMN can, but without renaming the column.You can use the modify SQL command if you need to resize a column in MySQL. By doing this you can allow more or less characters than before. You can't rename a column using modify and other

ALTER TABLE MyTable MODIFY COLUMN foo VARCHAR(32) NOT NULL AFTER baz;

Note : ALTER TABLE is used for altering a table means to change column name, size, drop column. CHANGE COLUMN and MODIFY COLUMN commands cannot be used without help of ALTER TABLE command.

Answer 5

Change Column : Used when we want to change the column name with its definition. eg - alter table student CHANGE name full_name VARCHAR(32) NOT NULL;

Modify column : Used when column name is to be same but change in its definition. eg - alter table student MODIFY full_name VARCHAR(64) NOT NULL;

Rename column : Used when we only need to change the column name (its definition will be same) alter table student RENAME COLUMN full_name TO name;