这个查询会查找所有以@example.com结尾的邮箱地址,并将其替换为@newexample.com。 这些示例展示了CASE WHEN在MySQL中的灵活性,无论是用于数据转换、排序定制,还是条件处理等场景。
一、Case When 法 Case When 句的基本语法如下: CASE WHEN 件 1 THEN 算式 1 WHEN 件 2 THEN 算式 2 … ELSE 算式 n END 在 Case When 句中,可以添加任意多的 when 句,每个 When 句都有一个对应的运算式,如果指定的条件匹配,则返回对应的运 算式;如果没有满足条件,则返回 Else 算式。 二、Case Wh...
表达式格式:CASE column WHEN 条件1 THEN 表达式1 WHEN 条件2 THEN 表达式2 ... ELSE 表达式 END [as] column_alias 即:查询数据时候 当满足1条件时候 column 值为表达式1 , 当满足2条件时候 column 值为表达式2... 若都不满足则为ELSE 后的表达式, 最后END 结束,起个别名,方便检索 For Example: 想将ty...
WHEN 1 THEN SET result = 'Input is 1'; WHEN 2 THEN SET result = 'Input is 2'; ELSE SET result = 'Input is neither 1 nor 2'; END CASE; SELECT result; END // DELIMITER ; 在这个例子中,我们创建了一个名为example_case_procedure的存储过程,它接受一个整数参数input。根据input的值,CASE...
Hi all, I have the below code using case when. I'd like to modify this though so that instead of the code using 1 for true it counts the distinct number of records that match the criteria in each case when section. If someone could please give me some example code?
The use of case-when can double the result with half the effort and solve more extensive and logically more compact problems. This paper introduces the business requirements, and then gives the implementation scheme, and then provides the example code, finally summarizes the application scenario. ...
statisticallkindsofonlinebusinessdataortoperformdatafilteringoperationundertheconditionofquery-field.Theuseofcase-whencandoubletheresultwithhalftheeffortandsolvemoreextensiveandlogicallymorecompactproblems.Thispaperintroducesthebusinessrequirements,andthengivestheimplementationscheme,andthenprovidestheexamplecode,finally...
In case none of the when_expression in the WHEN clause matches the value of the case_expression, the commands in the ELSE clause will execute. The ELSE clause is optional. If you omit the ELSE clause and no match found, MySQL will raise an error. The following example illustrates how to...
The exit value frommysqltestis 0 for success, 1 for failure, and 62 if it skips the test case (for example, if after checking some preconditions it decides not to run the test). mysqltestsupports the following options: --help, -?
SELECT COALESCE(NULL, NULL, NULL, 'Begtut.com', NULL, 'Example.com'); CONVERT- 将值转换为指定的数据类型或字符集 SELECT CONVERT("2017-08-29", DATE),CONVERT("2017-08-29", DATE); 功能与cast相近,datatype参数也可见附录二。 select SESSION_USER(), SYSTEM_USER(), USER(), VERSION(); ...