How to add non-empty constraint columns in SQL

The step of adding a non-empty constrained column with the ALTER TABLE statement includes determining the column to add the constraint. Use the NOT NULL keyword to specify the constraint. Execute the ALTER TABLE statement.

How to add non-empty columns using SQL

Steps to add non-empty constraint columns:

• Determine the columns to add non-empty constraints: Determine the columns you want to add to the table.
• Write an ALTER TABLE statement: Use the ALTER TABLE statement to add non-empty constraints.
• Specifying non-empty constraints: Use the NOT NULL keyword in the ALTER TABLE statement to specify non-empty constraints.
• Execution statement: Execute the ALTER TABLE statement.

Detailed description:

Here is a detailed description of how to add non-empty columns using SQL:

1. Add columns using the ALTER TABLE statement:

    <code class="sql">ALTER TABLE table_name ADD COLUMN column_name data_type NOT NULL;</code>

   in:

   • table_name is the table name to which you want to add a non-empty constraint column.
   • column_name is the name of the non-empty constraint column you want to add.
   • data_type is the data type of the column you want to add (for example, INT, VARCHAR, DATE, etc.).

2. Specify non-null constraints using the NOT NULL keyword:

   In the ALTER TABLE statement, the NOT NULL keyword is used to specify non-empty constraints. This means that the column cannot contain a NULL value.

3. Execute the ALTER TABLE statement:

   Execute the ALTER TABLE statement to add a non-empty constraint to the column.

Example:

The following example shows how to add a non-empty constraint column named phone_number to the customers table:

 <code class="sql">ALTER TABLE customers ADD COLUMN phone_number VARCHAR(20) NOT NULL;</code>

After executing this statement, phone_number column will be added to the customers table and it will have a non-empty constraint. This means that you cannot insert a NULL value into the column.

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