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Points to Ponder from Beginning SQL Joes 2 ProsVolume 1 (ISBN: 1-4392-5317-X) (Joes2Pros.com) September 5th, 2020

1. A query is written in the SQL language and is a request for information from data in a database.
2. Microsoft SQL Server uses the Transact Structured Query Language (T-SQL)
3. The percent % symbol is the most common …

Posted in SQLSERVER || Comments Off on Points to Ponder from Beginning SQL Joes 2 ProsVolume 1 (ISBN: 1-4392-5317-X) (Joes2Pros.com)
Regular Expressions in MS SQL Server 2005/2008 March 29th, 2017

https://www.codeproject.com/Articles/42764/Regular-Expressions-in-MS-SQL-Server

Posted in SQLSERVER || Comments Off on Regular Expressions in MS SQL Server 2005/2008
How can I create index on nvarchar(max) datatype in sql? March 27th, 2017

include , checksum, full-text index

http://stackoverflow.com/questions/12336821/how-can-i-create-index-on-nvarcharmax-datatype-in-sql

Posted in SQLSERVER || Comments Off on How can I create index on nvarchar(max) datatype in sql?
sql server 2008 sa账户无法登录,错误:233 December 5th, 2011

http://hi.baidu.com/cive/blog/item/bd4e8e82a714d0b26c81198d.html

重新安装了sql server 2008,发现sa账户无法登录,错误是233。

网上找了很多帖子,

设置了“SQL   Server和Windows身份验证模式”,

也设置了sa“启用”,

也重启了N次,

都不行,

偶然看到一个办法,一试就好了。

如下:

 

用Windows身份验证登录,执行SQL命令:

ALTER LOGIN sa WITH PASSWORD=’新密码’

搞定,现在终于可以用sa登录SQL管理器了。

Posted in SQLSERVER || Comments Off on sql server 2008 sa账户无法登录,错误:233
Recursive Relationships November 15th, 2011

Recursive relationships: relationships exist between entity instances of the same type.

One-to-one: If we were to track which employees were married to other employees, we would expect each to be married to either zero or one other employee at any …

Posted in DATABASE, ORACLE, SQLSERVER || Comments Off on Recursive Relationships
多对多必须通过单独的一张表来表示 November 15th, 2011

如班级和教师的关系由三张表来表示:班级表,教师 及 班级教师表

In particular, the logical model does not contain any many-to-many relationships. There is a simple rationale for this difference – relational databases do not directly support many-to-many relationships, so they must be transformed using an intersection entity.…

Posted in DATABASE, ORACLE, SQLSERVER || Comments Off on 多对多必须通过单独的一张表来表示
About Count November 11th, 2011

select count(*) FROM [AdventureWorks].[Person].[Contact]
返回表中所有的记录的个数

select COUNT(MiddleName) from [AdventureWorks].[Person].[Contact]
返回字段中,值非空的记录的个数(重复的也算进去的) 

select COUNT(distinct MiddleName) from [AdventureWorks].[Person].[Contact]
返回字段中不重复且非空的记录的个数

Result:
19972
11473
70…

Posted in ORACLE, SQLSERVER || Comments Off on About Count
Cursors in SQL November 6th, 2011

SQL was designed as a set-oriented processing language. Some business rules( or poor physical design) require performing actions on row-by-row basis. Consider the following example:
. Increase the price of books <=$15 by 15%
. Decrease the price of books …

Posted in DATABASE, ORACLE, SQLSERVER || Comments Off on Cursors in SQL
View – With Check Option November 2nd, 2011

Creating a view using With Check Option will restrict the queries to only those rows directly visible by the view.

http://www.sqlteam.com/FORUMS/topic.asp?TOPIC_ID=66019
It prevents row from dissappearing from the view implementing this option.
drop table  T100
go
drop view  VT100
go…

Posted in DATABASE, ORACLE, SQLSERVER || Comments Off on View – With Check Option
Basic Rules of Normalization November 1st, 2011

Without going into a dissertation on data modeling(itself a subject of many full-length treatises), tables should follow basic rules of normalization:

Avoid duplicate data, avoid repeating groups in tables, and only put data in tables where the information is directly

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