postgres=#insertintoaa(id)values(3); postgres=#select*fromaawhereagenotin(1,2); id | age ---+--- (0rows) postgres=#select*fromaawhereagenotin(1); id | age ---+--- 2 | 2 (1 row) postgres=# 这就是为什么postgresql对not in查询使用一个特殊的访问方法。 NOT EXISTS 1 2 3 4 ...
在我们平时写SQL时,如果遇到需要排除某些数据时,往往使用id <> xxx and id <> xxx,进而改进为id not in (xxx, xxx); 这样写没有问题,而且简化了SQL,但是往往有些极端情况,使用not in就会造成极大的性能损耗,例如: select * from test where id not in (select id from test_back) and info like '%t...
不幸的是,postgresql优化器不能利用到t_right.value被定义为not null的事实。因此,不可以返回null值。(即not in不能返回null值) 这里可以做一个小测试: postgres=# create table aa(id int,age int);postgres=# insert into aa values(1,1);postgres=# insert into aa values(2,2);postgres=# insert int...
SubLinkType subLinkType;/* see above */intsubLinkId;/* ID (1..n); 0 if not MULTIEXPR */Node *testexpr;/* outer-query test for ALL/ANY/ROWCOMPARE */List *operName;/* originally specified operator name */Node *subselect;/* subselect as Query* or raw parsetree */intlocation;/* to...
场景- NOT IN、NOT EXISTS 查询 (OLTP) 1、背景 not in 查询,多用在排除多个输入值场景。 实际上PostgreSQL支持很多种排除多个输入值的语法。 1、not in (...) 2、not in (table or subquery or srf) 3、<> all (array) 4、not exists (select 1 from (values (),(),...) as t(id) where ...
问postgresql使用'where not in‘子句优化查询EN数据库优化: 1.可以在单个SQL语句，整个应用程序，单个...
如果您使用 SELECT…WHERE x NOT IN(SELECT y FROM…)等“ NOT IN”编写SQL查询,必须了解当“ x”或“ y”为NULL时会发生什么?如果不是您想要的结果,我将在这里告诉您如何解决。 首先,一个简单的情况:如果“ x”和“ y”是使用NOT NULL子句创建的列,则它们永远不会为NULL。让我们考虑其他情况。复杂性源...
Wiki Security Insights Additional navigation options Closed as not planned Question Description anita970120 anita970120 added bug wait for review on Nov 21, 2022 LonwoLonwo added x:postgresql on Nov 21, 2022 LonwoLonwo commentedon Nov 21, 2022 ...
There have been, in the past, bugs in PostgreSQL that could cause data corruption even if the incoming connection was not authenticated. As good policy: Always have PostgreSQL behind a firewall. Ideally, it should have a non-routable private IP address, and only applications that are within ...
### Error querying database. Cause: org.postgresql.util.PSQLException: ERROR: LIMIT #,# syntax is not supported Hint: Use separate LIMIT and OFFSET clauses. Position: 162 ### The error may exist in com/shgbit/man/machine/manage/repository/mapper/ScenesMapper.java (best guess) ...