What is CASE WHEN in PostgreSQL? The CASE WHEN expression is used to implement conditional logic in SQL queries. It evaluates conditions and returns specific results based on whether the condition is true or false. It's commonly used in SELECT statements, but can also be used in WHERE, ORDER...
if-else, case, etc. TheCASEstatement is one of the conditional expressions that is used to create conditional queries. PostgreSQL allows us to use the WHEN-THEN case, if-else statements, etc. with the CASE statement to create or formulate a query/expression. ...
在检查Case When语句中的重复值时,可以采取以下步骤: 1. 理解Case When语句:Case When语句是一种条件表达式,用于根据不同的条件执行不同的操作。它通常用于SQL查询中,可以...
General PostgreSQL CASE expression The following illustrates the general form of the CASE statement: CASE WHEN condition_1 THEN result_1 WHEN condition_2 THEN result_2 [WHEN ...] [ELSE else_result] END In this syntax, each condition (condition_1, condition_2…) is a boolean expression that...
Keep in mind that, the column must be present in the SELECT statement of your query, on which you are specifying the boolean expressions (in CASE). But when you are using CASE in pair with a where clause, you need not to follow this (more on this later). The data-type of the ...
MySQL中的case when中对于NULL值判断的小坑 今天在开发程序中,从MySQL中提取数据的时候,使用到了case when的语法用来做判断,在使用过程中在判断NULL值的时候遇到个小问题; 具体的现象测试如下: 表结构如下: CREATE TABLE...when语法: 语法1: CASE case_value WHEN when_value THEN statement_list [WHEN when_va...
CASE WHEN condition_1 THEN statements_1 WHEN condition_2 THEN statements_2 ... WHEN condition_n THEN statements_n [ ELSE else_statements ] END CASE;] Code language: PostgreSQL SQL dialect and PL/pgSQL (pgsql) The searched CASE statement follows the rules below: The conditions in the WHEN...
The CASE statement uses IF-THEN-ELSE logic within a single statement. It facilitates conditional inquiries by doing the work of an IF-THEN-ELSE statement and applying it to many possible conditions. Syntax CASE condition WHEN condition value THEN statement ELSE additional stateme...
Note: CASE WHEN statements will always output new values to a new column which is different than “if then” which can replace values in the same column. Now let’s see what the full query would have looked like for that CASE WHEN statement, notice the title of the output column at the...
They differ in how they compare values or evaluate conditions. 3.1. Simple CASE To begin with,a simple CASE statement compares an expression to one or more possible values. It has a simple format: CASEexpressionWHENvalue1THENresult1WHENvalue2THENresult2 ...