T-SQL (Transact-SQL) is an extension to Structured Query Language, which is just as well used to interact with relational databases. It expands the capabilities of SQL by delivering procedural programming, local variables, a variety of support functions, as well as enhanced DELETE and UPDATE st...
When this T-SQL script is run, it creates a new Update stored procedure for the Order_Details table. All columns are accounted for as parameters in the new stored procedure code, but notice how the primary key columns (OrderID and ProductID) show up in the Where clause, while the other...
If Process 1 retrieves data and later attempts to modify it, and if Process 2 has modified the same data between the retrieval and modification, then SQL Server produces an error upon Process 1's modification attempt because of the conflict. Then, Process 1 can try to reissue the ...
Here’s what we use (and it works!) –“Query to find ‘hot’ boys”. We created and ran this class last year (at DigiGirlz) and we wanted to share it with you. Teach a teen-aged girl to code!All the setup instructions, code and answers are published on CodePlex – here....
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关系模型的一个关键要点是:一个关系代表一个集合(例如,Customers)。 为数据库设计数据模型是,所有数据都是用关系(数据表)来表示的。首先要确定一个命题,用户表示数据库中要保存的信息。 如“雇员Ben出生于1971年2月12日,你属于IT部门”就是一个命题。为真就表示Employees表中的一行,假就表示不是Employees表中的...
While T-SQL makes creating, modifying, and retrieving data more efficient,SolarWinds®SQL Sentrycan help ensure optimal efficiency. Not only does SQL Sentry offer visibility across your database environment at a glance, but it also provides fast root cause analysis, enabling you to identify and...
This lesson shows you how to create a database, create a table in the database, and then access and change the data in the table. Because this lesson is an introduction to using Transact-SQL, it doesn't use or describe the many options that are available for these statements....
·SQL语言中最主要、最核心的部分是它的查询功能。查询语言用来对已经存在于数据库中的数据按照特定的组合、条件表达式或次序进行检索。数据库中的查询是使用Select语句来完成的。 ·T-SQL中的查询基本结构:由SELECT子句(想要查看什么)、FROM子句(从哪查看)和WHERE子句(条件)组成; ...
l根据查询条件,建立索引,优化索引、优化拜访方式,制约结果集的数据量。注意填充因子要适当(最好是应用默认值0)。 l如果是应用like停止查询的话,简略的应用index是不可的,但是全文索引,耗空间。like 'a%'应用索引like '%a'不应用索引用like '%a%'查询时,查询耗时和字段值总长度成正比,所以不能用CHAR类型,而是...