Sql when then case

APPLIES TO: SQL Server Azure SQL Database Azure SQL Data Warehouse Parallel Data Warehouse Evaluates a list of conditions and returns one of multiple possible result expressions. So, once a condition is true, it will stop reading and return the result. If no conditions are true, it returns the value in the ELSE clause.

The OR operator in the WHEN clause of a CASE statement is not supported. Because of this pairing, you might be tempted to call this SQL CASE WHEN, but CASE is the accepted term. Every CASE statement must end with the. Zapytania w SQL do bazy danych to nie tylko proste porównania klucza lub innych kolumn.

Skorzystanie z tej metody znacząco ułatwia pobranie ściśle określonych danych, a przede wszystkim skraca kod naszego programu gdzie. To begin, we of initialize the CASE statement then specify under which conditions (WHEN) our CASE statement should evaluate a result. In this example, we’re examining the books. Tolkien-esque theme, THEN we return the value ‘Middle-earth.

If neither fields match our search, we instead return the value of ‘Earth. Starting in Oracle 9i, you can use the CASE statement within a SQL statement. Pour présenter le CASE dans le langage SQL il est possible d’imaginer une base de données utilisées par un site de vente en ligne. You can use case expressions anywhere you can use an expression. The CASE expression provides conditional SQL expressions.

The syntax of the CASE expression is as follows:. If the expression following the CASE statement is equal. Add some flexibility to your program flow in T- SQL with the CASE. Specifies the value that follows the THEN and ELSE keywords. It specifies the result of a searched- when -clause or a simple- when -clause that is true, or the result if no case is true.

There must be at least one result-expression in the CASE expression with a defined data type. NULL cannot be specified for every case. The following two PROC SQL steps show two equivalent CASE expressions that create a character column with the strings in the THEN clause.

THEN pairs meet this condition, and an ELSE clause exists, then Oracle returns else_expr. Otherwise, Oracle returns null. You cannot specify the literal NULL for every return_expr and the else_expr. In a searched CASE expression, Oracle searches from left to right until it finds an occurrence of condition that is true, and then returns return_expr. In a simple case statement, it evaluates conditions one by one.

Once the condition and expression are matche it returns the expression mentioned in THEN clause. Przypadki w MySQL – CASE WHEN THEN ELSE END. Podobnie jak w PHP, baza danych MySQL ma odpowiednik if, czyli przypadków (inaczej serii warunków, instrukcji warunkowych). Różnicą między implementacją CASE‘a w MySQL i ifa PHP jest to, że baza danych zwraca konkretną wartość z case’a, a nie wykonuje dowolnej ilości dowolnych akcji.

CASE WHEN işlemlerinde sonuçların gösterimi ile alakalı işlemler yapılırken kullanılmaktadır. IF-ELSE kullanmak yerine CASE – WHEN – THEN yapısını kullanmak hem kısa hemde daha kolay bir yol olacaktır. Here, the bool_expNs are tests that give a ternary boolean result: true, false, or NULL.

The first expression evaluating to TRUE determines the result. SQL Server CASE statement is equivalent to the IF- THEN statement in Excel. Wyrażenie CASE w SQL (IF THEN ELSE tylko w SQL) Wyrażenie CASE zapewnia funkcjonalność konstrukcji typu IF-THEN-ELSE w SQL. Wynik wyrażenia CASE może być m. SQL中的case when then else end用法. CASE can be used in any statement or clause that allows a valid expression.

For example, you can use CASE in statements such as SELECT, UPDATE, DELETE and SET, and in clauses such as select_list, IN, WHERE, ORDER BY, and HAVING. We could have spent countless hours to optimize their performance for dynamic SQL , but the better option would have been us the CASE expression in the WHERE clause. In the example below, NEWVAR is a character variable that is created based on the CASE condition that an observation meets.