search
Homephp教程PHP开发Basic knowledge of stored procedures in SQL Server

What is a stored procedure?
A stored procedure is one or more SQL commands stored in the database as executable objects.
In layman’s terms: a stored procedure is actually a set of SQL statements that can complete certain operations.

Then why use stored procedures?
1. Stored procedures are only compiled when they are created. There is no need to recompile each time the stored procedure is executed in the future. Generally, SQL statements are compiled once every time they are executed, so using stored procedures can improve the execution speed of the database.
2. When performing complex operations on the database, the complex operations can be encapsulated in stored procedures and used in conjunction with the transaction processing provided by the database.
3. Stored procedures can be reused, which can reduce the workload of database developers.
4. High security, you can set that only certain users have the right to use the specified stored procedure

How to use the stored procedure?
The following uses the Student table to learn about stored procedures. Because we want to understand the simple usage of stored procedures, all examples are very simple.

Basic knowledge of stored procedures in SQL Server

Stored procedure without parameters:
Select all the information in the Student table,

create proc StuProc
as      //此处 as 不可以省略不写
begin   //begin 和 end 是一对,不可以只写其中一个,但可以都不写
select S#,Sname,Sage,Ssex from student
end
go

Stored procedures with parameters:
Global variables
Global variables are also called external variables, which are defined outside the function. The scope starts from the place where the variable is defined and ends at the end of the program file.
Select the student information with the specified name:

create proc StuProc
@sname varchar(100)   
as 
begin
select S#,Sname,Sage,Ssex from student where sname=@sname
end
go

exec StuProc '赵雷'   //执行语句

The above is to assign a value to the variable externally, or you can directly set the default value for the variable internally

create proc StuProc
@sname varchar(100)='赵雷'
as 
begin
select S#,Sname,Sage,Ssex from student where sname=@sname
end
go

exec StuProc

You can also output the content of the variable, using output

create proc StuProc
@sname varchar(100),
@IsRight int  output //传出参数
as 
if exists (select S#,Sname,Sage,Ssex from student where sname=@sname)
set @IsRight =1
else
set @IsRight=0
go

declare @IsRight int 
exec StuProc '赵雷' , @IsRight output
select @IsRight

The above is a global variable , let’s learn about local variables
Local variables are also called internal variables. Local variables are defined within the function. Its scope is limited to the inside of the function, and it is illegal to use such variables after leaving the function.
The definition of local variables: they must be set with the Declare command before they can be used, declare{@variable name data type}
The assignment method of local variables: set{@variable name=expression} or select{@variable name=expression }
Display of local variables: select @variable name

create proc StuProc
as 
declare @sname varchar(100)
set @sname='赵雷'
select S#,Sname,Sage,Ssex from student where sname=@sname
go

exec StuProc

What if you want to display the data of local variables?

create proc StuProc
as 
declare @sname varchar(100)
set @sname=(select Sname from student where S#=01)
select @sname
go

exec StuProc


Statement
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

mPDF

mPDF

mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),

SecLists

SecLists

SecLists is the ultimate security tester's companion. It is a collection of various types of lists that are frequently used during security assessments, all in one place. SecLists helps make security testing more efficient and productive by conveniently providing all the lists a security tester might need. List types include usernames, passwords, URLs, fuzzing payloads, sensitive data patterns, web shells, and more. The tester can simply pull this repository onto a new test machine and he will have access to every type of list he needs.

VSCode Windows 64-bit Download

VSCode Windows 64-bit Download

A free and powerful IDE editor launched by Microsoft

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

MantisBT

MantisBT

Mantis is an easy-to-deploy web-based defect tracking tool designed to aid in product defect tracking. It requires PHP, MySQL and a web server. Check out our demo and hosting services.