ACID(Atomicity,Consitency,Isolation and Durability) SQL SERVER – ACID (Atomicity, Consistency, Isolation, Durability)… Read More
Points to Ponder from Beginning SQL Joes 2 ProsVolume 1 (ISBN: 1-4392-5317-X) (Joes2Pros.com) 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 wildcard. This symbol represents any number of characters. For example,WHERE Firstname like ‘%N’ would find a name… Read More
Regular Expressions in MS SQL Server 2005/2008 https://www.codeproject.com/Articles/42764/Regular-Expressions-in-MS-SQL-Server… Read More
How can I create index on nvarchar(max) datatype in sql? include , checksum, full-text index http://stackoverflow.com/questions/12336821/how-can-i-create-index-on-nvarcharmax-datatype-in-sql… Read More
sql server 2008 sa账户无法登录，错误：233 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。… Read More
Recursive Relationships 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 one point in time. One-to-many: It is common to track the employment “food chain” of … Read More
多对多必须通过单独的一张表来表示 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.… Read More
About Count 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… Read More
Cursors in SQL 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 > $15 by 10% Here is a set-oriented solution: update titles set price = price… Read More
View – With Check Option 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 Create table T100 (A int) GO Create view VT100 AS (SELECT * FROM T100 WHERE… Read More