Shulou(Shulou.com)05/31 Report--

This article introduces the relevant knowledge of "introduction to actual combat analysis of SQL Server". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

Environmental Information:

OS:Windows

Software:SQL Server 、 Microsoft SQL Server Management Studio

Type: T-SQL

Events: database management

Documentation: SQL Server2016 from beginner to actual combat

I. Overview of T-SQL

This language is a structured query language designed and developed by Microsoft Company. It is an extension of SQL and has the main features of standard SQL. This language can achieve all the functions that the graphical interface can accomplish.

1. Notes

The unexecuted part of the code is generally an explanation of the function. The line from the beginning to the end of the code is in the non-execution stage, a single-line comment, a text block wrapped in / * /, and is generally used in multi-line comments.

2. Variables

Local variable: a name that acts within the program, starting with @, and must be defined with declare before it can be used

# define declare {@ l_v1 data_type} [,... n] # assign set @ l_v1=expressionselect {@ l_v1=expression} [,... n] # display print @ l_v1select @ l_v1declare @ name varchar (8), @ sex varchar (2), @ age smallintdeclare @ address varchar (100) set @ address=' Xuancheng 'select @ address

Global variables: non-user-defined, server-level, starting with @ @

Commonly used global variables

@ @ connections returns the last time you started SQL Server, the number of attempts to connect @ @ error returns the error code for the last execution of the SQL statement @ @ rowcount returns the number of rows affected by the last statement @ @ servername returns the name @ @ version of the local server that allows SQL Server to return the date, version, and processor type of SQL Server currently installed @ @ language returns the language of the SQL Server server

3. Operator

Arithmetic operator, assignment operator, bit operator, comparison operator, logical operator, string concatenation operator

II. T-SQL statement

1 、 DML

Data manipulation language: query, insert, delete, update

Select

Insert

Delete

Update

2 、 DDL

Data definition language: defining structure and data relations, etc.

Create

Alter

Drop

3 、 DCL

Data control language: data integrity and storage control

Grant

Revoke

Deny

III. Process control

1. Process control keywords

Declare: declare variables

Begin...end: define statement blocks

Berak: exit the while loop

Continue: restart the loop

Goto label: continue processing from the statement after label

If...else: two-branch judgment

Case...when...then...end: multi-branch judgment

Return: exit

Waitfor: waiting delay

While: cyclin

Print: output

2. Grammar format

Begin {select 、 insert 、 update... } endif xxx xxx if xxx xxxelse xxx xxx case xxxwhen xxx then xxx...when xxx then xxxelse xxxendwhile xxx xxx [bread] xxx [continue] "introduction to the actual combat analysis of SQL Server" ends here. Thank you for your reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!

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