易截截图软件、单文件、免安装、纯绿色、仅160KB

linq to sql生成not in语句的小技巧

以前一直觉得linq to sql生成类似where id not in (1,3,5)或where id not in (select id from ...)这样的条件不是很方便,每次我都是把条件ID事先取到一个数组里,然后用 !Arr.Contains(c.Id)这样处理,今天突然发现这样好傻,其实可以完全直接用linq写成一句,贴个示例在这里,以后备查
from a in TableA where !(from b in TableB Where ... select b.Id).Contains(a.Id)
最终翻译出来的语句并非跟not in 完全一样的,而是用not exists(...),不过效果完全相同,能达到要求就行了!


相关文档:

ORACLE PL/SQL 对象(object)学习笔记(二)

4、对象依赖性
 
CREATE OR REPLACE TYPE Obj1 AS OBJECT (
f1 NUMBER,
f2 VARCHAR2(10),
f3 DATE
);
/

CREATE OR REPLACE TYPE Obj2 AS OBJECT (
f1 DATE,
f2 CHAR(1)
);
/

CREATE OR REPLACE TYPE Obj3 AS OBJECT (
a Obj1,
b Obj2
);
/
  
 
OBJ3依赖于OBJ ......

sql server 内存表

--1加内存表
EXEC sp_tableoption '表名','pintable', 'true' 
--2卸载内存表
EXEC sp_tableoption '表名','pintable', 'false' 
--2查询是否有内存表驻留
SELECT * from INFORMATION_SCHEMA.Tables 
WHERE TABLE_TYPE = 'BASE TABLE' 
          AND OBJECTPROP ......

ORACLE和POSTGRESQL的SQL语句比较

oracle 方法                                                & ......

SQL语句PART7

Merge statement
function benefits: 1) provides the ability to conditionally update, insert or delete data into a database table. 2) performs an update if the row exists, and an insert if it is a new row. --> 1) avoids seperate updates, 2) increase performance and ease of use. 3) is useful in dat ......

SQL语句PART11


1. My test: (create and grant the sysdba to a new user by SQL*Plus)
CREATE USER FJTEST1 IDENTIFIED BY JEANJEANFANG;
GRANT SYSDBA TO FJTEST;
REVOKE SYSDBA from FJTEST;
CONNECT FJTEST1/JEANJEANFANG AS SYSDBA;
2. Using ORAPWD in windows:
C:\» ORAPWD;
(show help information)
3. to see th ......
© 2009 ej38.com All Rights Reserved. 关于E健网联系我们 | 站点地图 | 赣ICP备09004571号