How To Write Not Null in Sql Query

In SQL, when you want to enforce that a particular column must not contain NULL values, you can use the NOT NULL constraint. This constraint ensures that every row in the table must have a non-NULL value for that column. Here's an example of how you can use it in a CREATE TABLE statement:

sql
CREATE TABLE YourTableName (
Column1 DataType1 NOT NULL,
Column2 DataType2,
-- other columns and constraints
);

In this example, Column1 is defined as NOT NULL, which means that every row inserted into the table must have a non-NULL value for Column1.

If you want to add the NOT NULL constraint to an existing table, you can use the ALTER TABLE statement:

sql
ALTER TABLE YourTableName
ALTER COLUMN Column1 DataType1 NOT NULL;

This query will alter the table by adding the NOT NULL constraint to Column1.

If you want to insert data into a table and ensure that a column is not NULL, you can specify the values explicitly for the columns that should not be NULL:

sql
INSERT INTO YourTableName (Column1, Column2, ...)
VALUES (Value1, Value2, ...);

Make sure to provide a non-NULL value for the columns with the NOT NULL constraint.

For example:

sql
INSERT INTO YourTableName (Column1, Column2)
VALUES ('SomeValue', 'AnotherValue');

This will insert a new row with non-NULL values for Column1 and Column2.

If you attempt to insert a row without providing a value for a column with the NOT NULL constraint, or if you try to update a row and set the value of a NOT NULL column to NULL, the database will raise an error. This helps maintain data integrity by preventing the insertion of incomplete or inconsistent data.

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