In this tutorial, you have learned how to use the PostgreSQL IN operator to check if a value matches any value in a list of values. The PostgreSQL IN condition is used to help reduce the need to use multiple OR conditions in a SELECT, INSERT, UPDATE, or DELETE statement. ORDER BY customer_id Code language: SQL (Structured Query Language) ( sql )įor more information on the subquery, check it out the subquery tutorial. ![]() WHERE CAST (return_date AS DATE) = '' ORDER BY customer_id Code language: SQL (Structured Query Language) ( sql )īecause this query returns a list of values, you can use it as the input of the IN operator like this: SELECT The following query returns a list of customer ids from the rental table with the return date is : SELECT customer_id This query returns the same output as above query that use the NOT IN operator. Similar to the IN operator, you can use the not equal ( ) and AND operators to write the NOT IN operator: SELECTĬustomer_id 1 AND customer_id 2 Code language: SQL (Structured Query Language) ( sql ) If all the expressions corresponding to WHEN are evaluated to be False. SELECTĬustomer_id NOT IN ( 1, 2) Code language: SQL (Structured Query Language) ( sql ) Each condition is a boolean expression and based on its output the result is chosen. You can combine the IN operator with the NOT operator to select rows whose values do not match the values in the list.įor example, the following statement finds all rentals with the customer id is not 1 or 2. In addition, PostgreSQL executes the query with the IN operator much faster than the same query that uses a list of OR operators. The query that uses the IN operator is shorter and more readable than the query that uses equal ( =) and OR operators. It is equivalent to the query above: SELECTĬustomer_id = 1 OR customer_id = 2 ORDER BY The following query uses the equal ( =) and OR operators instead of the IN operator. Return_date DESC Code language: SQL (Structured Query Language) ( sql ) CREATE OR REPLACE FUNCTION public. ![]() Suppose you want to know the rental information of customer id 1 and 2, you can use the IN operator in the WHERE clause as follows: SELECT customer_id, Note that you will learn more about the subquery in the subsequent tutorial PostgreSQL IN operator examples The query inside the parentheses is called a subquery, which is a query nested inside another query. The list of values can be a list of literal values such as numbers, strings or a result of a SELECT statement like this: value IN ( SELECT column_name FROM table_name) Code language: SQL (Structured Query Language) ( sql ) The IN operator returns true if the value matches any value in the list i.e., value1, value2, … The syntax of the IN operator is as follows: value IN (value1,value2.) Code language: SQL (Structured Query Language) ( sql ) You use IN operator in the WHERE clause to check if a value matches any value in a list of values. The conditions represent the requirements that must be met in. The tables syntax is the table or tables from which you want to extract the results. WHERE CASE WHEN x 0 THEN y/x > 1.Summary: in this tutorial, you will learn how to use the PostgreSQL IN operator in the WHERE clause to check if a value matches any value in a list. The simplest form of the SELECT statement syntax is: SELECT expressions FROM tables WHERE conditions The expressions are all the columns and fields you want in the result. For example, this is a possible way of avoiding a division-by-zero failure: The example above can be written using the simple CASE syntax:Ī CASE expression does not evaluate any subexpressions that are not needed to determine the result. This is similar to the switch statement in C. If no match is found, the result of the ELSE clause (or a null value) is returned. The first expression is computed, then compared to each of the value expressions in the WHEN clauses until one is found that is equal to it. There is a “ simple” form of CASE expression that is a variant of the general form above: The data types of all the result expressions must be convertible to a single output type. ![]() If the ELSE clause is omitted and no condition is true, the result is null. If no WHEN condition yields true, the value of the CASE expression is the result of the ELSE clause. If the condition's result is not true, any subsequent WHEN clauses are examined in the same manner. 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. Each condition is an expression that returns a boolean result. The SQL CASE expression is a generic conditional expression, similar to if/else statements in other programming languages:ĬASE clauses can be used wherever an expression is valid.
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