有几个子查询必须遵循的规则:必须用括号括起来的子查询。...ORDER BY不能使用在子查询中,虽然主查询就可以使用ORDER BY。GROUP BY可以用来执行相同的功能在子查询中的ORDER BY。...子查询返回多于一行只能用于使用多值的运算符,如为IN,EXISTS,IN,ANY / SOME,ALL运算符。...CASE表达式是一种通用的条件...
ORDER BY CASE constellation WHEN'白羊'THEN1WHEN'金牛'THEN2WHEN'双子'THEN3WHEN'巨蟹'THEN4WHEN'狮子'THEN5WHEN'处女'THEN6WHEN'天秤'THEN7WHEN'天蝎'THEN8WHEN'射手'THEN9WHEN'摩羯'THEN10WHEN'水瓶'THEN11WHEN'双鱼'THEN12END DESC
具有limit 1和order by不需要的where条件的PostgreSQL慢查询 具有特殊条件的PostgreSQL连接 具有多个案例的sql连接 VBA选择案例有多个条件 事务列表上具有多个联接条件的SQL请求(postgreSQL) 具有多个条件的条件回归 具有多个子串规则的Mysql案例 具有条件和多个排序列的Order by case语句以及else 具有多个条件的SUM IF 具有...
e.salary,CASEWHENe.salary<5000THEN'低'WHENe.salary<15000THEN'中'ELSE'高'ENDASsalary_levelFROMemployees eORDERBYCASEWHENe.salary<5000THEN3WHENe.salary<15000THEN2ELSE1END, first_name; 缩写函数 除了以上两种形式的CASE表达式之外,PostgreSQL还提供了两个与NULL相关的缩写CASE表达式(函数):NULLIF和COALEASE。
order by "Average Salary" DESC; 1. 2. 3. 4. 补充: Union(union all): 指令的目的是将两个 SQL 语句的结果集合并起来,得到你所需要的查询结果。 Union:对两个结果集进行并集操作,不包括重复行,同时进行默认规则的排序; Union All:对两个结果集进行并集操作,包括重复行,不进行排序; ...
order by case when publish_date >= publish_date - 7 then 1 when publish_date >= publish_date - 30 then 3 else 3 end, ts_rank(tsvector_ft,q) desc; 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. RUM索引-比ES 7.x还快 ...
case when (now()-query_start) is null then 'NULL' else (now()-query_start)::text end||chr(10)|| 'SQL (Current SQL in Transaction): '||chr(10)|| case when current_query is null then 'NULL' else current_query::text end, chr(10)||'---'||chr(10) order by ( case mode w...
distinctfromw.classidandr.objidisnotdistinctfromw.objidandr.objsubidisnotdistinctfromw.objsubidandr.transactionidisnotdistinctfromw.transactionidandr.pid <> w.pidorderby((casew.modewhen'INVALID'then0when'AccessShareLock'then1when'RowShareLock'then2when'RowExclusiveLock'then3when'ShareUpdateExclusive...
If Order By isn't specified, the rows will be returned in an unspecified order. The actual order in that case will depend on the scan and join plan types and the order on disk, but it must not be relied on.Creating a connectionThe connector supports the following authentication types:...
postgre中没有类似的函数,可以重写为case... when... substr(str, int, int) Oracle中的substr用来取一个字符串的子串,PostgreSQL有同名的函数实现类似功能。不同的是Oracle中,第二、第三个参数可以为负数,代表从后面进行计数,PostgreSQL不允许其为负数,需对其进行转换。Oracle中是以0开始计数,PostgreSQL以1开始计...