How to Find the Name of a Constraint in SQL

If you're working with a SQL database, you may need to find the name of a constraint. Constraints are rules that are applied to a database to ensure data integrity and accuracy. To find the name of a constraint in SQL, use the INFORMATION_SCHEMA.TABLE_CONSTRAINTS view. This view contains information about all the constraints in a database, including the name of the constraint. To find the name of a constraint, you can use the following query:

SELECT CONSTRAINT_NAME
FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS
WHERE TABLE_NAME = 'table_name'
AND CONSTRAINT_TYPE = 'constraint_type';

In this query, table_name is the name of the table that the constraint is applied to, and constraint_type is the type of constraint (e.g. PRIMARY KEY, FOREIGN KEY, etc.).

Examples

Let's look at a few examples of how this query can be used. Suppose you have a table called users with the following data:

‍
If you wanted to find the name of the primary key constraint for this table, you would use the following query:

SELECT CONSTRAINT_NAME
FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS
WHERE TABLE_NAME = 'users'
AND CONSTRAINT_TYPE = 'PRIMARY KEY';

This query would return the result users_pkey, which is the name of the primary key constraint for the users table.

Additional Info

The INFORMATION_SCHEMA.TABLE_CONSTRAINTS view is supported by most major databases, including MySQL, PostgreSQL, and SQL Server. However, the syntax may vary slightly depending on the database you are using. For more information, check out the documentation for your particular database.