Does ALTER TABLE modify delete data?

Does altering table delete data?

No it will not erase your data. It will add a column and all the existing data will be assigned null values in this column.

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.

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.

How do I edit a table without losing data?

There are some good fixes for this issue:1Set a default value (recommended) for the column you're creating.2Create the column without the NOT NULL , set the appropiate values, and then make the column NOT NULL .