Shulou(Shulou.com)06/01 Report--

The MySQL IFNULL function is one of the MySQL control flow functions, which takes two arguments and returns the first parameter if it is not NULL. Otherwise, the IFNULL function returns the second argument. The syntax structure of the IFNULL function IFNULL (expression_1,expression_2); the IFNULL application instance USE testdb; CREATE TABLE IF NOT EXISTS contacts (contactid INT AUTO_INCREMENT PRIMARY KEY,contactname VARCHAR (20) NOT NULL,bizphone VARCHAR (15), homephone VARCHAR (15)); note that you should avoid using the IFNULL function in the WHERE clause because it degrades the performance of the query. The article is from www.huthon.cn.

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