Postgres return boolean if exists In PostgreSQL, the EXISTS operator is used to determine whether a subquery returns rows. This tutorial covers everything you need to know, from basic syntax to advanced techniques. Feb 22, 2019 · This is my rookie attempt to create a function where it would return True or False depending on whether a table exists in the db. B) NOT EXISTS example C) EXISTS and NULL See more Introduction to PostgreSQL EXISTS operator The EXISTS operator is a boolean operator that tests for existence of rows in a subquery. If you use EXISTS, you just won't get the record if it is filtered out. This makes it particularly useful for writing efficient queries where you only need to know if certain Currently, I have query like this: SELECT (EXISTS(SELECT 1 FROM "user" WHERE password = <password> AND username = <username> LIMIT 1))::bool; It works, but it is two sub queries, and I was wondering if there is a better way to write a query to check the existence of a value? Sep 25, 2025 · RETURN expression; RETURN with an expression terminates the function and returns the value of expression to the caller. Master the PostgreSQL EXISTS condition with this comprehensive guide. I guess the correct query will be: SELECT count(1) > 0 FROM table WHERE column = <value>; In my case exist() takse 3ms to execute the query but count() takes whooping 20ms so I would suggest to go with exist (). Aug 3, 2023 · PostgreSQL EXISTS examples A) Find customers who have at least one payment whose amount is greater than 11. Unfortunately it outputs an empty table, and no raised messages; Sep 6, 2025 · The powerful and flexible PostgreSQL EXISTS operator checks if a subquery returns any records. Learn how to use EXISTS with SELECT, INSERT, UPDATE, and DELETE statements, including handling NULLs and NOT EXISTS scenarios. How can I do such query in Postgres? IF (select count(*) from orders) > 0 THEN DELETE from orders ELSE INSERT INTO orders values (1,2,3); Dec 7, 2016 · Then, ::boolean converts the string value true / false back into a PostgreSQL boolean value. Apr 15, 2014 · PostgreSQL: Update function return boolean Asked 11 years, 7 months ago Modified 3 years, 7 months ago Viewed 35k times Mar 19, 2024 · Show you how to use three forms of the PL/pgSQL IF statement that executes a command based on a certain condition. Sep 2, 2023 · Fastest check if row exists in PostgreSQL Introduction Have you ever needed to check if a row exists in a PostgreSQL table quickly and efficiently? Maybe you're working with batches of data and want to know if a single row from the batch already exists in the table. All of the expression forms documented in this section return Boolean (true/false) results. The `EXISTS` clause in PostgreSQL is a conditional expression used to determine whether a subquery returns any rows. My conf is Postgresql with 88862 rows of table. It is often used in `SELECT`, `UPDATE`, and `DELETE` statements to test the presence of records in a subquery. Nov 22, 2023 · CREATE FUNCTION InList (_Key INTEGER, _PARENT INTEGER) RETURNS BOOLEAN AS $$ BEGIN RETURN EXISTS (SELECT 1 From SimpleListTable WHERE Key0 = _Key AND ParentKey = _PARENT LIMIT 1); END; $$ LANGUAGE plpgsql; Dec 5, 2020 · Good evening, hopefully my question is not too stupid, but - in a 13. Jul 1, 2024 · This tutorial shows you how to use the PostgreSQL EXISTS operator to check the existence of rows in the subquery. If the subquery returns at least one row, EXISTS returns true, otherwise returns false. Advanced query construction requires it, especially when searching for relevant data without retrieving it. Rather than returning actual data, the EXISTS operator returns a boolean value (TRUE or FALSE) based on whether the subquery returns any rows at all. Jul 23, 2013 · SELECT ::INT (SELECT EXISTS ( SELECT id FROM user WHERE membership=1244)) But I'm getting a syntax error. A: The postgresql if in select statement is a conditional operator that allows you to return a different value depending on whether a specified value is present in a table. But to return a composite (row) value, you must write Sep 19, 2016 · How to return a boolean true/false instead of t/f from a field of string type in Postgres. I have a function that checks if an outer key exists in some_json and returns a boolean. Sep 25, 2025 · Each condition is an expression that returns a boolean result. 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. This form is used for PL/pgSQL functions that do not return a set. Jul 14, 2014 · In most cases 'count (1) > 0' leads to cleaner looking code. Use the EXISTS operator to check based on data in the related table. Jun 10, 2015 · I want to execute a dynamic SQL statement, with its returned value being the conditional for an IF statement: Check if two values exists and return named boolean Asked 6 years, 2 months ago Modified 6 years, 2 months ago Viewed 255 times Mar 8, 2015 · Note that key_a and key_b are optional keys mapped to dictionaries and may or may not exist. In a function that returns a scalar type, the expression's result will automatically be cast into the function's return type as described for assignments. If it exists, it should return me a string true and stop the search there itself and if not return false. An alternative title might be: Check for existence of multiple rows? Using a combination of SQL and C# I want a method to return true if all products in a list exist in a table. (If your column is of some other type, use the appropriate cast for the type of your column. If it can be done. Oct 8, 2024 · This tutorial explains how to check if a row exists in a table in PostgreSQL, including an example. In Postgres, the EXISTS operator takes a subquery as an argument and checks the existence of a record in the subquery. Jul 15, 2025 · Conclusion In summary, the PostgreSQL IF statement is a important element for introducing conditional logic into your SQL queries and functions. In this blog post, we'll explore common issues surrounding this question and provide easy solutions to help you achieve the This section describes the SQL -compliant subquery expressions available in PostgreSQL. Can you tell the best way to handle this? Should I be casting the resulting 't' to a boolean somehow? or is there a way to tell postgresql to return true / false instead of 't'/'f'? Thanks. In this article, we will explain the EXISTS operator in detail, complete with practical examples and outputs. If the condition's result is not true, any subsequent WHEN clauses are examined in the same manner. Each condition is an expression that returns a boolean result. If the condition's result is true, the value of the CASE expression is the result that follows the condition, and the remainder of the CASE expression is not processed. The following illustrates syntax of the EXISTS operator: This PostgreSQL tutorial explains how to use the PostgreSQL EXISTS condition with syntax and examples. Jul 12, 2025 · The EXISTS operator returns true if the subquery returns at least one row otherwise it return false. So I want to check if a single row from the batch exists in the table because then I know they Aug 10, 2012 · I'm writing a function in PL/pgSQL, and I'm looking for the simplest way to check if a row exists. 1 database I have a words_users table with a boolean column: -- the user is not allowed to chat or change the motto muted boolean NOT NULL DEFAULT false, Currently I check the value as follows, but I wonder if this is the best way with PL/pgSQL - IF EXISTS (SELECT 1 FROM words_users WHERE uid = _uid AND muted) THEN RAISE Jul 28, 2019 · At now I use code like that create function something() returns boolean as $$ begin if exists (select 1 from some_table where some_cond) then return false; end if; insert into In this tutorial, you'll learn how to execute one or more statements based on a condition using the PL/pgSQL IF statement. Consequently, it returns true or false. So EXISTS acts as a filter. SELECT (CASE WHEN status = 'active' THEN true ELSE false END)::boolean AS status FROM table; The PostgreSQL EXISTS operator returns true if the subquery produces any rows or false otherwise. In PostgreSQL (version 9. If you want to display a boolean value, you'll be better off with a CASE. ) This section describes the SQL -compliant subquery expressions available in PostgreSQL. PostgreSQL EXISTS Introduction The EXISTS operator is a powerful SQL feature that allows you to test for the existence of rows in a subquery. Learn how to use the PostgreSQL IF statement in your SELECT queries with this comprehensive guide. 4, pgAdmin3), when doing select on a table with boolean column the data output shows 't' or 'f'. The EXISTS operator returns TRUE if the sub query returns one or more records. Jun 30, 2012 · I want to the query to check if a particular row exists or not in a table. Right now I'm SELECTing an integer into a boolean, which doesn't really work. This article talks about the EXISTS operator, its use cases, and examples. I have a bunch of rows that I need to insert into table, but these inserts are always done in batches. By mastering PostgreSQL conditional statements, you can customize your database operations to handle various scenarios efficiently. Apr 14, 2025 · SQL EXISTS is a logical operator that adds considerable flexibility to your database queries. I would like to cast/convert booleans as TRUE or FALSE without writing CASE The EXISTS operator is used to test for the existence of any record in a sub query. Introduction to PostgreSQL EXISTS operator The EXISTS operator is a boolean operator that checks the existence of rows in a subquery. Practical examples demonstrate its usage for efficient data manipulation. iy6gwc hc5tu 90v 2bqbz pgdsjxiv jynvf ri bl61 xwk brwftk