Basic usage of IF case conditional statement in MySQL

An If expression

IF (EXPR1,EXPR2,EXPR3)

If Expr1 is true (expr1 <> 0 and Expr1 <> NULL), then the return value of if () is expr2; Otherwise, the return value is EXPR3. The return value of IF () is a numeric value or a string value, depending on the context in which it is located

Examples are as follows:

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SELECT IF (score>=60, ' Pass ', ' fail ') from score; Mysql> SELECT IF (1>2,2,3); -> 3 Mysql> SELECT IF (1<2, ' yes ', ' no '); -> ' yes ' Mysql> SELECT IF (STRCMP (' Test ', ' test1 '), ' no ', ' yes '); -> ' No '

If the result is greater than 2, then the case will be used, the syntax is:

Case field name when value 1 THEN result 1 when value 2 THEN result 2 Else other result end
Examples are as follows:

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SELECT Case Value When 1 THEN ' A ' When 2 THEN ' B ' When 3 THEN ' C ' ELSE ' D ' End as text From Test;

If case stored procedure

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Wrong wording CREATE PROCEDURE test (in a int) If a > 1 Then Select 1; ElseIf A>2 Then Select 2; Else End If; To determine the wording of a CREATE PROCEDURE test (in a int) If a > 1 Then Select 1; ElseIf A>2 Then Select 2; Else --Doing nothing-- Set @tmp = 1; End If;

Example

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DROP PROCEDURE IF EXISTS text; Create PROCEDURE text ( out RTN int  ) begin  declare loginID int default 0;  set rtn=1;   if loginID = 3  then   set rtn=2;  elseif loginid = 0  then  &N Bsp;set rtn=3;  else   set rtn=4;  end IF; End