How to Find the Name of a Constraint in PostgreSQL Database: PostgreSQL Operators: CONSTRAINT PRIMARY KEY FOREIGN KEY UNIQUE DEFAULT CHECK Problem: You want to find the names of the constraints in a table in PostgreSQL. Example: We want to display the names of the constraints in the table student. Solution: SELECT conname, contype FROM pg_catalog.pg_constraint JOIN pg_class t ON t.oid = c.conrelid WHERE t.relname ='student'; Here is the result: connamecontype student_age_checkc student_pkeyp student_personal_number_keyu student_country_id_fkeyf Discussion: To find the name of a constraint in PostgreSQL, use the view pg_constraint in the pg_catalog schema. Join the view pg_catalog.pg_constraint with the view pg_class (JOIN pg_class t ON t.oid = c.conrelid) and use the relname column to filter the constraints by table name. In our example, we select the constraints from the table student (WHERE t.relname ='student'). Select columns conname and contype to see the constraint name along with the constraint type. In the column contype, the value ‘p’ is for a primary key, ‘f’ is for a foreign key, ‘u’ is for the UNIQUE constraint, and ‘c’ is for the CHECK constraint. For example, you can see the constraint named student_pkey for the primary key in the student table. The contype column tells you the type of the constraint, which for the primary key is p. The conname column in this view also tells you about the table containing this constraint. Recommended courses: The Basics of Creating Tables Data Types in SQL SQL Constraints Recommended articles: What is a Primary Key in SQL? How to Create a Table in SQL Referential Constraints and Foreign Keys in MySQL Understanding Numerical Data Types in SQL See also: How to Create a Primary Key in SQL How to Remove a Primary Key in SQL Subscribe to our newsletter Join our monthly newsletter to be notified about the latest posts. Email address How Do You Write a SELECT Statement in SQL? What Is a Foreign Key in SQL? Enumerate and Explain All the Basic Elements of an SQL Query