Part1-了解 SQL CASE 语句 CASE 语句提供了在 SQL 查询中执行条件逻辑的方法。它评估一组条件并根据第一个评估为 true 的条件返回结果。 CASE语句的语法如下: 代码语言:javascript 代码运行次数:0 AI代码解释 CASEWHENcondition1THENresult1WHENcondition2THENresult2...ELSEdefault_resultEND 以下是每个部分的细分: ...
condition1, condition2等是要检查的条件。 result1, result2等是条件匹配时返回的结果。 ELSE子句是可选的,用于指定当没有条件匹配时返回的默认结果。 例如,假设有一个名为"age"的列,存储了用户的年龄信息,我们可以使用搜索CASE表达式将年龄分为不同的年龄段: 例如,假设有一个名为"age"的列,存储了用户的年龄...
TheCASEexpression evaluates its conditions sequentially and stops with the first condition whose condition is satisfied. In some situations, an expression is evaluated before aCASEexpression receives the results of the expression as its input. Errors in evaluating these expressions are possible. Aggregate...
TheCASEexpression evaluates its conditions sequentially and stops with the first condition whose condition is satisfied. In some situations, an expression is evaluated before aCASEexpression receives the results of the expression as its input. Errors in evaluating these expressions are possible. Aggregate...
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SQL数据库高级知识汇总 CASE函数的类型 CASE具有两种格式,简单CASE函数和CASE搜索函数。这两种方式,大部分情况下可以实现相同的功能。 简单CASE函数 语法 CASE column WHEN <condition> THEN value WHEN <condition> THEN value … ELSE value END 示例 CASE sex ...
当然,以下是如何在 SQL Server 中使用 `CASE WHEN` 语句并将其嵌入到条件语句(如 `SELECT`, `UPDATE`, `DELETE`, 和 `WHERE` 子句)中的示例。 ### 基本语法 ```sql CASE WHEN condition1 THEN result1 WHEN condition2 THEN result2 ... ELSE default_result END ``` ### 在 SELECT 语句中使用 ...
2) Case:a) If the value of the <search condition> of some <searched when clause> in a <...
17.5 -0 ,it is greater than zero, but my sql always return 0 as result I try to amend sql to the following sql, it is correct, it return '' (blank) as expect, why I can't calculate in the true condition (after then ...) select...
IN谓词——OR的简便用法 使用子查询作为 IN 的参数: EXIST 谓词 EXIST 通常都会使用关联子查询作为参数,这里我们用EXIST选取出“大阪店在售商品的销售单价” : 就像EXIST可以用来替换IN一样,NOT IN也可以用NOT EXIST来替换: 3. CASE表达式 CASE WHEN <condition1> THEN <表达式> WHEN <condition2> THEN <表...