https://www.postgresqltutorial.com › postgresql-tutorial › postgresql-exists
PostgreSQL EXISTS Operator - PostgreSQL TutorialLearn how to use the EXISTS operator to test for the existence of rows in a subquery. See examples of basic, NOT EXISTS, and NULL cases with the customer and payment tables.
PostgreSQL CTE examples. Let’s explore some examples of using common table expressions (CTE). 1) Basic PostgreSQL common table expression example. The following example uses a common table expression (CTE) to select the title and length of films in the 'Action' category and returns all the columns of the CTE:
We use the if statement to check if the film with id (0) exists and raise a notice if it does not.
https://stackoverflow.com › questions › 11892233
sql - PL/pgSQL checking if a row exists - Stack OverflowSimpler, shorter, faster: EXISTS. IF EXISTS (SELECT FROM people p WHERE p.person_id = my_person_id) THEN -- do something END IF; The query planner can stop at the first row found - as opposed to count() , which scans all (qualifying) rows regardless.
https://stackoverflow.com › questions › 11299037
sql - PostgreSQL IF statement - Stack OverflowPostgreSQL doesn't have IF, instead use a SELECT CASE WHEN statement, as in: SELECT CASE WHEN 50<100 THEN 5 ELSE 10 END; which allows a: SELECT CASE WHEN 50<(select count(*) from sometable) THEN 5 ELSE 10 END from mytable;
https://www.postgresql.org › docs › current › functions-conditional.html
PostgreSQL: Documentation: 17: 9.18. Conditional ExpressionsThe SQL CASE expression is a generic conditional expression, similar to if/else statements in other programming languages: CASE WHEN condition THEN result . [WHEN ...] [ELSE result] END. CASE clauses can be used wherever an expression is valid. Each condition is an expression that returns a boolean result.
https://www.postgresql.org › docs › current › functions-subquery.htm
PostgreSQL: Documentation: 17: 9.24. Subquery ExpressionsThe argument of EXISTS is an arbitrary SELECT statement, or subquery. The subquery is evaluated to determine whether it returns any rows. If it returns at least one row, the result of EXISTS is “true”; if the subquery returns no rows, the result of EXISTS is “false”.
https://www.postgresqltutorial.com › postgresql-plpgsql › plpgsql-if-else-statements
PL/pgSQL IF Statement - PostgreSQL TutorialWe use the if statement to check if the film with id (0) exists and raise a notice if it does not.
https://www.techonthenet.com › postgresql › exists.php
PostgreSQL: EXISTS Condition - TechOnTheNetThis PostgreSQL tutorial explains how to use the PostgreSQL EXISTS condition with syntax and examples. The PostgreSQL EXISTS condition is used in combination with a subquery and is considered to be met if the subquery returns at least one row.
https://www.w3schools.com › postgresql › postgresql_exists.php
PostgreSQL EXISTS Operator - W3SchoolsThe EXISTS operator is used to test for the existence of any record in a sub query. The EXISTS operator returns TRUE if the sub query returns one or more records.
https://www.guru99.com › fr › postgresql-exists.html
PostgreSQL Existe avec l'exemple de sélection, d'insertion ... - Guru99Dans ce nouvel article concernant notre nouveau projet PostgreSQL Didacticiel sur la requête Exists, nous apprendrons ce qu'est la requête Exists dans PostgreSQL avec des exemples d'instructions de sélection, d'insertion, de mise à jour et de suppression.
https://www.sqliz.com › postgresql › exists
PostgreSQL EXISTSIn PostgreSQL, the EXISTS operator is used to determine whether a subquery returns rows. If the subquery returns at least one row, EXISTS returns true, otherwise returns false. PostgreSQL EXISTS syntax
