Does ALTER TABLE delete existing data?

Does ALTER TABLE change data?

The basic syntax of an ALTER TABLE command to change the DATA TYPE of a column in a table is as follows. ALTER TABLE table_name MODIFY COLUMN column_name datatype; The basic syntax of an ALTER TABLE command to add a NOT NULL constraint to a column in a table is as follows.

What does ALTER TABLE modify do?

The ALTER TABLE statement is used to add, delete, or modify columns in an existing table. The ALTER TABLE statement is also used to add and drop various constraints on an existing table.

What does alter column do?

The ALTER COLUMN command is used to change the data type of a column in a table.

What Cannot be performed with ALTER TABLE command?

- Column can't be deleted with alter command. - Column can't be renamed a column. - Column can't be added in between of the existing columns.