Mariadb Alter Table Add Column if Not Exists Example - SQL

Introduction

In Mariadb, ALTER TABLE statement is used to add a new column to an existing table. However, if the table already has the same column, then the ALTER TABLE statement will fail with an error. To avoid this error, Mariadb provides the "IF NOT EXISTS" clause with ALTER TABLE statement that enables you to add a column to a table only if the column does not exist in the table.

In this article, we will discuss how to use the "IF NOT EXISTS" clause with ALTER TABLE statement to add a column to a Mariadb table only if the column does not exist.

Add Column If Not Exists Syntax

The syntax for adding a column to a Mariadb table only if the column does not exist is as follows:

ALTER TABLE table_name ADD COLUMN IF NOT EXISTS column_name data_type [DEFAULT default_value] [NULL|NOT NULL];

Add Column If Not Exists Example

Let's take an example to understand how to use the "IF NOT EXISTS" clause with ALTER TABLE statement to add a column to a Mariadb table only if the column does not exist.

Suppose we have a table "students" that already has a column "name", and we want to add a new column "age" to this table only if the "age" column does not exist.

The following code snippet shows how to add a column to a Mariadb table only if the column does not exist:

ALTER TABLE students ADD COLUMN IF NOT EXISTS age INT DEFAULT 25 NOT NULL;

In the above code snippet, we used the "IF NOT EXISTS" clause with the ALTER TABLE statement to add the "age" column to the "students" table only if it does not exist. We also provided a default value of 25 for the "age" column and made it NOT NULL.

Conclusion

In Mariadb, you can use the "IF NOT EXISTS" clause with the ALTER TABLE statement to add a new column to an existing table only if the column does not exist. This saves you from encountering an error if you try to add a column that already exists in the table. In this article, we discussed the syntax and provided an example of how to use the "IF NOT EXISTS" clause with ALTER TABLE statement to add a column to a Mariadb table only if the column does not exist.