SQL stored procedure

Method statement ：
Method name Parameters call Return value
The parameters are mainly one-to-one corresponding Dean
1. Corresponding types ： A child class can replace a parent class int-dount
2. The number of corresponding ： The default value is 、 Variable parameters
3. Sequence correspondence ： have access to Parameters ： Value method call
Return value ： adopt return Return value . But only a single value can be returned
Can pass Ref/out Extended method's " Return value "
void show( Parameters )
{
Custom local variables
Logical statement
}

Stored procedure and function creation are similar
Stored procedure syntax
go
create procedure usp_ Stored procedure name
( Shape parameter ) -- Parameters can be defined in this
as -- Equivalent to method body
{
– Custom local variables
– Logical statement
}
go

Example 1
Create stored procedure , Check all student information

if exists(select * from sysobjects where name = 'usp_getAllStuInfo') -- If stored procedure usp_getAllStuInfo There is , Just delete 
drop proc usp_getAllStuInfo
go
create procedure usp_getAllStuInfo -- Create stored procedure usp_getAllStuInfo
as
	select * from student
go
-- Calling stored procedure , Get all student information 
exec usp_getAllStuInfo

Calling stored procedure usp_getAllStuInfo Result ：

Example 2
Create stored procedure , Query the student information of the specified gender

if exists(select * from sysobjects where name = 'usp_getAllStuInfoBySex')
drop proc usp_getAllStuInfoBySex
go
create procedure usp_getAllStuInfoBySex
	@sex char(1) -- Formal parameters only need to be declared , It's not a definition , So no need declare
as
	select * from student where Gender = @sex
go
-- Calling stored procedure usp_getAllStuInfoBySex, Query male student information 
Exec usp_getAllStuInfoBySex 1

Calling stored procedure usp_getAllStuInfoBySex Result ：

Example 3
Create stored procedure , Query the student information of the specified gender and class ,（ The stored procedure defaults to gender male ）

-- Create stored procedure , Query the student information of the specified gender and class 
if exists(select * from sysobjects where name = 'usp_getAllStuInfoBySexAndGradeId') -- If stored procedure usp_getAllStuInfoBySexAndGradeId Delete if it exists 
drop proc usp_getAllStuInfoBySexAndGradeId
go 
create procedure usp_getAllStuInfoBySexAndGradeId -- Create stored procedure usp_getAllStuInfoBySexAndGradeId
	@sex char(1) = 1,	-- Formal parameters only need to be declared , It's not a definition , So no need declare, Add commas between multiple formal parameters 
	@gradeName nvarchar(20)
as
	declare @gradeId int = (select gradeid from grade where gradeName = @gradeName)
	select * from student where Gender = @sex and GradeId = @gradeId
go
-- Execute stored procedures usp_getAllStuInfoBySexAndGradeId, Query the student information of the specified gender and class 
Exec usp_getAllStuInfoBySexAndGradeId 1,' Social University 1'

Calling stored procedure usp_getAllStuInfoBySexAndGradeId , The result of specifying gender ：
Calling stored procedure usp_getAllStuInfoBySexAndGradeId , The result of not formulating gender ：

	-- The parameters are passed in the same order ： The first argument corresponds to the first parameter ... By analogy 
	-- If there is a default value , have access to  default 
	-- You can also use   Parameters = value   Call stored procedures in a way （ Note that once invoked in this way , Then the subsequent parameters must also use this method , Otherwise, the report will be wrong , The previous parameters are irrelevant ）, This has nothing to do with order 
	Exec usp_getAllStuInfoBySexAndGradeId default,' Social University 1'
	-- perhaps 
	Exec usp_getAllStuInfoBySexAndGradeId @gradeName =' Social University 1'