不要使用NOT IN使用子查询。正如jarlh在评论中所说，当任何值NULL，则不返回任何行。相反，要习惯NOT ...
1. select 查询 in、not in、exists、not exists 的区别 exists 效率远远大于 in CREATESEQUENCE "ioc_dw_second"."test0002_seq" INCREMENT1MINVALUE1MAXVALUE9223372036854775807START1CACHE1CYCLE ;CREATETABLE"ioc_dw_second"."test0002" ( "rid" int4NOTNULLDEFAULTnextval('"ioc_dw_second".test0002_seq':...
005.PGSQL-in、 notin、 exists、 notexists、 using的 sel。。。 1. select 查询 in、not in、exists、not exists 的区别 exists 效率远远大于 in CREATE SEQUENCE "ioc_dw_second"."test0002_seq" INCREMENT 1 MINVALUE 1 MAXVALUE 9223372036854775807 START 1 CACHE 1 CYCLE ; CREATE TABLE "ioc_dw_se...
最近用explain命令分析查询sql执行计划,时而能看到Extra中显示为"Using index"或者"Using where; Using Index",对这两者之间的明确区别产生了一些疑惑,于是通过网上搜索、自行实验探究了一番其具体区别。 测试数据准备 以下表作为测试表进行sql分析。 CREATE TABLE `test_table`(`id` bigint(20)unsigned NOTNULLAU...
官方的定义是，MySQL must do an extra pass to find out how to retrieve the rows in sorted ...
(17695,'Pl/SQL', 1980), -> (19264,'JavaScript', 1992), -> (19354,'www.java2s.com', 1993); Query OK, 8 rows affected (0.03 sec) Records: 8 Duplicates: 0 Warnings: 0 mysql> mysql> mysql> CREATE TABLE Authors( -> AuthID SMALLINT NOT NULL PRIMARY KEY, -> AuthFN VARCHAR(20),...
The SUBSTRING function returns@domain.com.I don't want any results to be displayed from my sql statement if it equals@myemail.com. I have other cases too that are not relevant to my question. I'm getting an error that says invalid syntax near < ...
Hi, Im used to being able to do the following SQL query in ms access to compare two sets of data in one table like follows: (select accname from users where scanID=1) not in (select accname from users where scanID=2) The Source Table layout is as follows: ...
in web browser. If I deploy it to a test area under IIS, the correct string values are displayed instead of System.Byte[].How to repeat:Install the .NET connector, version 5.1.6 Create a new Web Form (.aspx page) Add a SqlDataSource and bind it to a simple control like a ...
However, if we only need to log anot activestatement and not theactivestatement. So there is no way for us to log thenot activewithout having to change the conditional logic. That’s where aif notstatement comes in. With aif notstatement, we will not need to have aelsestatement. Then,...