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 运行 AI代码解释 CASEWHENcondition1THENresult1WHENcondition2THENresult2...
在SQL查询中,WHERE条件下的CASE语句用于根据条件动态生成表达式或值。它允许根据不同的条件返回不同的结果。 CASE语句有两种形式:简单CASE表达式和搜索CASE表达式。 1. 简单CA...
cast as the declared type of the <case specification>.b) If no <search condition> in a <case...
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...
SQL CASEThe SQL CASE statement evaluates a list of conditions and adds a column with values based on the condition. For example, -- add a new column 'order_volume' in the Orders table -- and flag any order greater than 10000 as 'Large Order' -- and smaller than 10000 as 'Small ...
The CASE expression evaluates its conditions sequentially and stops with the first condition whose condition is satisfied. In some situations, an expression is evaluated before a CASE expression receives the results of the expression as its input. Errors in evaluating these expressions are possible. ...
我们使用的条件表达式使用的 When 和 Case 的函数,这个其实就对应于 SQL 里的 CASE 和 WHEN 函数。 我们先来说一下需求,我们在获取 Client 数据的时候,想要知道这条数据 registered_on 日期字段所在的季节,比如 1月就是 Spring,7月就是 Autumn。
If no match is found among the WHEN clauses, the action in the ELSE clause is returned. Syntax Simple CASE statement used to match conditions: CASE expression WHEN value THEN result [WHEN...] [ELSE result] END Searched CASE statement used to evaluate each condition: CASE WHEN condition ...
---流程函数在一个SQL语句中实现条件选择 模拟对职员薪水进行分类: mysql> create table salary_tab(useridintnotnullprimary key,salary dec(9,2)); Query OK,0rows affected (0.04sec) mysql> insert into salary_tab values(1,1000); mysql> insert into salary_tab values(2,2000); ...