在CASE WHEN SQL语句中处理不存在的记录,可以通过使用COALESCE函数或者LEFT JOIN语句来实现。 使用COALESCE函数: COALESCE函数用于返回参数列表中的第一个非NULL值。在处理不存在的记录时,可以将COALESCE函数用于CASE WHEN语句的条件判断中,将不存在的记录替换为一个默认值。例如: 代码语言:tx
搜索CASE表达式的基本语法如下: 代码语言:txt 复制 CASE WHEN condition1 THEN result1; WHEN condition2 THEN result2; ... ELSE result; END CASE; 其中,condition是一个逻辑表达式,根据其结果来决定返回哪个result。如果没有条件满足,则返回else后面的result。 使用IF或CASE with multiple条件可以实现很多功能,例...
避免分母为0,或者使用CASE WHEN语法绕过。 创建MySQL兼容性插件,开启允许除以0的开关,详情请参见迁移MySQL至Hologres。 ERRCODE_STRING_DATA_RIGHT_TRUNCATION 报错:value too long for type character varying(xxx) 问题原因:字段长度超过了VARCHAR类型的长度限制。
CASE WHEN condition1 THEN result1 WHEN condition2 THEN result2 -- Add more WHEN conditions and results as needed END AS alias_name FROM table_name; We can add as many WHEN ... THEN conditions as required in the CASE statement. For example, -- multiple CASE conditions in SQL SELECT ...
select sal, case when sal < 2000 then 'category 1' when sal < 3000 then 'category 2' when sal < 4000 then 'category 3' else 'category 4' end from emp; E.g.: The requirement is to find out the count of employees for various conditions as given below. There are multiple ways of...
The when_expression argument is any valid SQL Server expression. The data types of input_expression and each when_expression must be the same or must be implicitly converted.n A placeholder indicating that multiple WHEN when_expression THEN result_expression clauses, or multiple WHEN Boolean_...
-- Deriving multiple logical records from each physical record. -- -- Using a WHEN clause. -- -- Loading the same field (empno) into multiple tables. -- -- TO RUN THIS CASE STUDY: -- 1. Before executing this control file, log in to SQL*Plus as ...
在SQL 中,使用 `CASE WHEN` 语句时,可以通过添加额外的条件来处理空值(NULL)情况。这通常涉及到检查某个字段是否为 NULL,并针对这种情况返回特定的结果。以下是一个处理空值的 `...
CASEWHENwhen_expressionTHENresult_expression[ ...n ] [ELSEelse_result_expression]END Arguments input_expression The expression evaluated when the simpleCASEformat is used.input_expressionis any validexpression. WHENwhen_expression A simple expression to whichinput_expressionis compared when the simpleCASEf...
case when coalesce(c1,c2,c3) nvl(c1,c2) 7. 日期函数 获得当前时区的UNIX时间戳: unix_timestamp() 时间戳转日期函数:from_unixtime() 日期转时间戳:unix_timestamp(string date) 日期时间转日期函数:to_date(string timestamp) 日期转年函数:year(string date) 日期转月函数:month (string...