sql存储过程详解

USE TSQLFundamentals2008;
GO
IF OBJECT_ID('usp_ProcDemoNoParam','P') IS NOT NULL DROP PROC usp_ProcDemoNoParam;
GO
-- 1，不带参数
CREATE PROC usp_ProcDemoNoParam
AS
BEGIN
  SELECT * FROM HR.Employees;
END
GO

USE TSQLFundamentals2008;
GO
-- 1，不带参数存储过程的调用
EXEC usp_ProcDemoNoParam;

IF OBJECT_ID('usp_ProcDemoWithInputParam','P') IS NOT NULL DROP PROC usp_ProcDemoWithInputParam;
GO
-- 2，带输入参数
CREATE PROC usp_ProcDemoWithInputParam
  @empid AS INT
AS
BEGIN
  SELECT * FROM HR.Employees
  WHERE empid= @empid;
END
GO

-- 2，带输入参数存储过程调用
EXEC usp_ProcDemoWithInputParam @empid=5;

IF OBJECT_ID('usp_ProcDemoWithInputOutputParam','P') IS NOT NULL DROP PROC usp_ProcDemoWithInputOutputParam;
GO
-- 3，带输入和输出参数
CREATE PROC usp_ProcDemoWithInputOutputParam
  @empid AS INT,
  @NumRowsAffected AS INT OUTPUT
AS
BEGIN
  SELECT * FROM HR.Employees
  WHERE empid= @empid;
  
  SET @NumRowsAffected= @@ROWCOUNT; -- 赋值，也可以使用select赋值
END
GO

-- 3，带输入和输出参数存储过程的调用
DECLARE @nums AS INT;
EXEC usp_ProcDemoWithInputOutputParam @empid=5,@NumRowsAffected= @nums OUTPUT;
SELECT @nums AS nums;

IF OBJECT_ID('usp_ProcDemoWithReturnValue','P') IS NOT NULL DROP PROC usp_ProcDemoWithReturnValue;
GO
-- 4，带返回值
CREATE PROC usp_ProcDemoWithReturnValue
  @empid AS INT
AS
BEGIN
  IF EXISTS (SELECT * FROM HR.Employees WHERE empid=@empid)
    RETURN 1
  ELSE
    RETURN 0; -- 也可以声明一个变量，然后返回这个变量
END
GO

-- 4，带返回值存储过程的调用
DECLARE @status AS INT=0; --给默认值为0
EXEC @status= dbo.usp_ProcDemoWithReturnValue @empid = 5 -- int
SELECT @status AS thestatus;