Alter Table Modify Column Oracle Remove Not Null

First example the constraints with the desc sql plus command.

Alter table modify column oracle remove not null. Allow or not allow null values. Alter table customers modify customer name varchar2 100 not null. To modify a column of a table you need to specify the column name table name and action that you want to perform. Let s look at an example that shows how to modify a column in an oracle table using the alter table statement.

Once the alteration to your column is made it is a good practice to verify the column no longer allows any null values by running a simple insert test and trying to insert a new record with the null value in the altered column. Sql sql sql alter table employee modify first name not null. Alter table table name modify column name null for example to drop the not null constraint from the amount column of the surcharges table you use the following statement. Shorten or widen the size of the column.

Alter table invoice modify mycol null. This oracle alter table example will modify the column called customer name to be a data type of varchar2 100 and force the column to not allow null values. The statement is straightforward. Sql sql sql sql sql clean the table sql drop table employee 2 table dropped.

Oracle allows you to change a table with a not null constraint to a null constraint with an alter table statement. For complete tips on oracle alter table syntax see the book easy oracle jumpstart. To do this you need to remove the not null constraint from the column by using the alter table statement as below. If you are brave you can use a single alter table syntax to modify multiple columns.

Alter table table name modify column name datatype. Next you can alter the table column to make it allow null values. Oracle alter table modify column syntax example oracle database tips by donald burleson. Oracle provides alter table syntax to modify data columns in place in this form.