CASE WHEN 语句可以嵌套使用,以处理更复杂的条件逻辑。嵌套 CASE WHEN 的语法如下: sql SELECT column1, CASE WHEN condition1 THEN CASE WHEN nested_condition1 THEN nested_result1 WHEN nested_condition2 THEN nested_result2 ELSE nested_default_result END WHEN condition2 THEN result2 ELSE default_result...
搜索CASE WHEN语句: CASE WHEN condition1 THEN result1 WHEN condition2 THEN result2 ... ELSE result END 复制代码 根据条件进行匹配,如果满足condition1,则返回result1;如果满足condition2,则返回result2;否则返回result。 嵌套CASE WHEN语句: CASE WHEN condition1 THEN CASE WHEN nested_condition1 THEN nes...
这种用法是根据列的值来判断条件,并返回对应的结果。 搜索CASE WHEN语句: CASE WHEN condition1 THEN result1 WHEN condition2 THEN result2 ... ELSE result END 复制代码 这种用法是根据条件进行判断,并返回对应的结果。 嵌套CASE WHEN语句: CASE WHEN condition1 THEN CASE WHEN nested_condition1 THEN nest...
--在支持窗口函数的 sql 中使用 selectcount(casewhen rn=1then task_idelsenullend)task_numfrom(select task_id,row_number()over(partition by task_id order by start_time)rn from Task)tmp; 此外,再借助一个表 test 来理理 distinct 和 group by 在去重中的使用: 代码语言:javascript 代码运行次数:...
嵌套CASE语句可以在WHEN或ELSE后面再嵌套一个CASE语句,用于处理更复杂的条件逻辑。例如: 代码语言:txt 复制 CASE WHEN condition1 THEN CASE WHEN nested_condition1 THEN nested_result1 WHEN nested_condition2 THEN nested_result2 ... ELSE nested_resultN END WHEN condition2 THEN result2 ... ELSE resultN...
1.select子句中尽量避免使用* select子句中，*是选择全部数据的意思。比如语句：“select * from 成绩表...
WHEN'MD'THEN'Maryland' WHEN'UT'THEN'Utah' ENDASStateName FROMpubs.dbo.authors ORDERBYau_lname DECODE is considered the most powerful function in Oracle. Oracle 8i release introduced the CASE expression. The CASE expression can do all that DECODE does plus lot of other things including IF-THEN...
默认是read committed,这种情况一般在更新表的时候,如果不使用hint 提示,基本是先对表添加IX锁,级别不算高,基本和其他锁兼容,但是repeatable read,serializable 事务隔离级别就会先对表添加IX锁,然后向X锁转化,而X锁和大多数锁都不兼容,容易发生表阻塞。
[Error 10081]: UDTF's are not supported outside the SELECT clause, nor nested in expressions UDTF explode不能写在别的函数内如果你这么写,想查两个字段,select explode(split(area,',')) as area,good_id from explode_lateral_view; 会报错FAILED: SemanticException 1:40 Only a single expression ...
2. |--Nested Loops(Left Semi Join, PASSTHRU:([tempdb].[dbo].[TableAssert].[ID_Genders] IS NULL), OUTER REFERENCES:([tempdb].[dbo].[TableAssert].[ID_Genders]), DEFINE:([Expr1008] = [PROBE VALUE])) 3. |--Assert(WHERE:(CASE WHEN [tempdb].[dbo].[TableAssert].[Gender]<>'F'...