SQL server stored procedures multi angle introduction suggestions collection

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What is stored procedure ：

stored procedure （Procedure） Be similar to C# Methods in language , It is SQL Statement and control flow statement . Stored procedures are stored in the database , Can be executed by the application through a single call , And allow users to declare variables 、 Logic control statements and other powerful programming functions .

Stored procedures can contain logical control statements and data operation statements , It can receive parameters 、 Output parameters 、 Returns a single or multiple result sets and return values .

Stored procedures are compiled on the server when they are created , So the execution is more than a single SQL Fast sentence .

Be similar to C# Class library in ,SQL Server Some precompiled stored procedures are provided , These stored procedures are called “ System stored procedure ”.

SQL Server The characteristics of stored procedures in are as follows ：

1> Receive input parameters , And return a value to the calling procedure or statement .

2> Contains programming statements that perform operations in the database or call other stored procedures .

3> Return the status value to the calling procedure , Indicates whether the execution process was successful （ If you fail , Also return the failure reason ）

Using stored procedures has the following advantages ：

1> Allow modular programming

Just create the stored procedure once and store it in the database , Therefore, the procedure can be called any time in the program .

2> Allow faster execution

If an operation requires a lot of T-SQL Code may need to be executed repeatedly , Stored procedures will be T-SQL The execution of batch code should be fast . Stored procedures will be analyzed and optimized when they are created , And you can use the version in memory of the process after the first execution of the process . But if T-SQL Batch code , Each run T-SQL When the sentence is , It should be sent repeatedly from the client , And in SQL-Server Every time these statements are executed , It should be compiled and optimized .

3> Reduce network traffic

After creating and using stored procedures , One needs hundreds of lines T-SQL The operation of the code , It can be realized by a single statement that executes the procedure code , Instead of sending hundreds of lines of code over the network

4> It can be used as a security mechanism

Even for users who do not have permission to directly execute statements in stored procedures , They can also be granted permission to execute the stored procedure

There are two types of stored procedures ：

1> System stored procedure

2> User defined stored procedures

Common system stored procedures ：

sp_databases： List all databases on the server

sp_helpdb： Reports information about the specified database or all databases

sp_renamedb： Change the name of the database

sp_tables： Return the list of objects that can be queried in the current environment

sp_columns： Return the information of a table column

sp_help： View all the information of a table

sp_helpconstraint： Look at the constraints of a table

sp_helpindex： Look at the index of a table

sp_stored_procedures： List all stored procedures in the current environment

sp_password： Add or modify the password of the login account

sp_helptext： Show default 、 Unencrypted stored procedures 、 User defined stored procedures 、 The actual text of the trigger or view

in addition , There is also a commonly used extended stored procedure ：xp_cmdshell, It can do DOS Some operations under the command , Such as creating folders 、 List documents, etc .

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User defined stored procedures ：

In addition to system stored procedures , Users can also create their own stored procedures , You can use Microsoft SQL Management Studio Or use T-SQL sentence , Use Microsoft SQL Management Studio The steps to create a stored procedure are similar to views , Used to create stored procedures T-SQL Statement for CREATE PROCEDURE. All stored procedures are created in the current database .

Create a stored procedure without parameters ：

Use T-SQL The syntax of creating a stored procedure with the statement is as follows ：

CREATE PROC[EDURE] Stored procedure name

AS

SQL sentence

Calling stored procedure ：

EXEC Stored procedure name

Create a stored procedure with input parameters ：

Input parameters ： You can pass parameters to the stored procedure at call time , Such parameters can be used to pass values in stored procedures .

Stored procedure with input parameters T-SQL The statement is as follows ：

CREATE PROC[EDURE] Stored procedure name

@ Parameters 1 data type [ = The default value is ],

……,

@ Parameters n data type [ = The default value is ]

AS

SQL sentence

Calling stored procedure ：

EXEC Stored procedure name Parameters 1 Value ,……, Parameters n Value

or

EXEC Stored procedure name @ Parameters 1= value ,……,@ Parameters n= value

Create a stored procedure with output parameters ：

Output parameters ： If you want to return a value , You can use the output parameter , There are after the output parameters “OUTPUT” Mark , After executing the stored procedure , The return value will be stored in the output parameter , For other purposes T-SQL Statement read access .

Stored procedures with output parameters T-SQL The grammar is as follows ：

CREATE PROC[EDURE] Stored procedure name

@ Parameters 1 data type [ OUTPUT ],

……,

@ Parameters n data type [ OUTPUT ]

AS

SQL sentence

Calling stored procedure ：

EXEC Stored procedure name Variable name OUTPUT

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