子查询(Sub Query)或者说内查询(Inner Query),也可以称作嵌套查询(Nested Query),是一种嵌套在其他 SQL 查询的 WHERE 子句中的查询。 子查询用于为主查询返回其所需数据,或者对检索数据进行进一步的限制。 子查询可以在 SELECT、INSERT、UPDATE 和 DELETE 语句中,同 =、<、>、>=、<=、IN、BETWEEN 等运算符一...
Navigate:Previous Message•Next Message Options:Reply•Quote Subject Written By Posted Sub querys in MySQL Claus X May 30, 2006 04:16PM Re: Sub querys in MySQL Bill Karwin June 02, 2006 08:04PM Sorry, you can't reply to this topic. It has been closed....
1.程序的逻辑不同。通常sub query比较符合程序的逻辑结构 2.运行的效率不同。通常认为join要高效些。 子查询的数量越多。效率越低。10倍以上时间差距是肯定的。而且这个还是数量不多情况的保守估计。如果类别过多。这个倍数就会越大。 3.一般新手更多的使用sub query因为要简单直观些。有用 回复 撰写回答 你尚未...
-- This query completes in 110 seconds on the same test machine -- With larger data set it never completes (or more than several hours) SELECT count(*) FROM (SELECT distinct Key3 FROM test) t; -- The two queries complete approx. the same time on MySQL 8.0.16 -- The problem still...
Description: mysql5.1.50 crash when using partition in query using InnoDB Plugin 1.0.11 SELECT count(*) FROM part_date3 p where c3 in (select c3 from part_date3 t where t.c3 < date '2011-04-26 19:19:44' and t.c3 > date '2011-04-26 19:18:44') ; my.cnf config ignore_...
Quick BI中MySQL数据源,两段自定义SQL关联,抽取加速报错“sync error. java.sql.SQLException: errCode = 2, detailMessage = Syntax error in line 38: ... AS tmp ) count_sub_query ^ Encountered: EOF Expected”。 2024-06-12 15:03:55 [INFO] [manual] initialize job context, jobHistoryId:cb50...
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However, I have a subquery which returns data on MSSQL, but no data on MySQL the subquery below refers to ordersh.orddate, which is in the main query. When I alter that to a physical date (stored as integer 20080931 etc), the query runs (which isn't helpful to what i'm trying ...