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This article mainly introduces "what are the methods of using MySQL process control functions". In daily operation, I believe many people have doubts about the use of MySQL process control functions. Xiaobian consulted all kinds of materials and sorted out simple and easy-to-use operation methods. I hope it will be helpful for you to answer the doubts about "what is the use of MySQL process control functions?" Next, please follow the editor to study!

In MySQL, you can use IF (), IFNULL (), NULLIF (), ISNULL () functions to control the process.

1. The use of the IF () function

IF (expr1,expr2,expr3) returns the value of expr2 if the value of expr1 is true, and the value of expr3 if the value of expr1 is false.

SELECT IF (TRUE,'A','B');-- output result: ASELECT IF (FALSE,'A','B');-- output result: use of B2, IFNULL () function

IFNULL (expr1,expr2) returns the value of expr2 if the value of expr1 is null, and the value of expr1 if the value of expr1 is not null.

SELECT IFNULL (NULL,'B');-- output result: BSELECT IFNULL ('HELLO','B');-- output result: use of HELLO3, NULLIF () function

NULLIF (expr1,expr2), if expr1=expr2 is established, the return value is null, otherwise the return value is the value of expr1.

SELECT NULLIF;-- output result: nullSELECT NULLIF;-- output result: the use of A4, ISNULL () function

ISNULL (expr) returns 1 if the value of expr is null and 0 if the value of expr1 is not null.

SELECT ISNULL (NULL);-- output result: 1SELECT ISNULL ('HELLO');-- output result: 0 so far, the study of "what is the use of MySQL flow control function" is over, hoping to solve everyone's doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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