SQL Server中的SELECT语句用于从数据库中检索数据。在SELECT语句中,CASE WHEN子句用于根据条件执行不同的操作。 CASE WHEN子句的语法如下: 代码语言:txt 复制 SELECT column1, column2, ..., CASE WHEN condition1 THEN result1 WHEN condition2 THEN result2 ... ELSE result END FROM table_name; 在上述语法...
CASE AlarmEventTransactions.DeviceID应该就是CASE。您正在混合the 2 forms of theCASEexpression。
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. --Syntax for SQL Server and Azure SQL DatabaseSimple...
CASE AlarmEventTransactions.DeviceID应该就是CASE。您正在混合the 2 forms of theCASEexpression。
SQL USEAdventureWorks2022; GOSELECTProductNumber,Category=CASEProductLineWHEN'R'THEN'Road'WHEN'M'THEN'Mountain'WHEN'T'THEN'Touring'WHEN'S'THEN'Other sale items'ELSE'Not for sale'END,NameFROMProduction.ProductORDERBYProductNumber; GO B. Use a SELECT statement with a searched CASE expression ...
SQL WITHData(value)AS(SELECT0UNIONALLSELECT1)SELECTCASEWHENMIN(value) <=0THEN0WHENMAX(1/value) >=100THEN1ENDFROMData; GO 应仅依赖于标量表达式(包括返回标量的非相关子查询)的 WHEN 条件的计算顺序,而不应依赖于聚合表达式。 还必须确保 THEN 或 ELSE 子句中至少有一个表达式不是 NULL 常量。 虽然可...
The CASE statement can be used in SQL Server (Transact-SQL). You could use the CASE statement in a SQL statement as follows: (includes theexpressionclause) SELECT contact_id, CASE website_id WHEN 1 THEN 'TechOnTheNet.com' WHEN 2 THEN 'CheckYourMath.com' ELSE 'BigActivities.com' END ...
CASE can be used in any statement or clause that allows a valid expression Only 10 levels of nesting are allowed in SQL Server Syntax example The syntax for the SELECT statement with a simple CASE expression is as follows: SELECT CASE expression WHEN condition1 THEN result1 WHEN condition2 TH...
如果使用Case函数,我们只要一条SQL语句就可以解决问题,具体如下所示 SELECTstd_id,CASEWHENCOUNT(*) = 1--只选择一门课程的学生的情况THENMAX(class_id)ELSEMAX(CASEWHENmain_class_flg ='Y'THENclass_idELSENULLEND)ENDASmain_classFROMStudentclassGROUPBYstd_id; ...
We have following syntax for a case statement in SQL with a simple expression 1 2 3 4 5 6 SELECT CASE Expression When expression1 Then Result1 When expression2 Then Result2 ... ELSE Result END Usually, we store abbreviations in a table instead of its full form. For example, in my...