使用SQL存储过程有什么好处
■SQL存储过程执行起来比SQL命令文本快得多。当一个SQL语句包含在存储过程中时，服务器不必每次执行它时都要分析和编译它。
■调用存储过程，可以认为是一个三层结构。这使你的程序易于维护。如果程序需要做某些改动，你只要改动存储过程即可
■你可以在存储过程中利用Transact-SQL的强大功能。一个SQL存储过程可以包含多个SQL语句。你可以使用变量和条件。这意味着你可以用存储过程建立非常复杂的查询，以非常复杂的方式更新数据库。
■最后，这也许是最重要的，在存储过程中可以使用参数。你可以传送和返回参数。你还可以得到一个返回值（从SQL RETURN语句）。
环境:WinXP+VB6+sp6+SqlServer2000
数据库:test
表:Users
CREATE TABLE [dbo].[users] (
[id] [int] IDENTITY (1, 1) NOT NULL ,
[truename] [char] (10) COLLATE Chinese_PRC_CI_AS NULL ,
[regname] [char] (10) COLLATE Chinese_PRC_CI_AS NULL ,
[pwd] [char] (10) COLLATE Chinese_PRC_CI_AS NULL ,
[sex] [char] (10) COLLATE Chinese_PRC_CI_AS NULL ,
[email] [text] COLLATE Chinese_PRC_CI_AS NULL ,
[jifen] [decimal](18, 2) NULL
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]
GO
ALTER TABLE [dbo].[users] WITH NOCHECK ADD
CONSTRAINT [PK_users] PRIMARY KEY CLUSTERED
(
[id]
) ON [PRIMARY]
GO
存储过程select_users
CREATE PROCEDURE select_users @regname char(20), @numrows int OUTPUT
AS
Select * from users
SELECT @numrows = @@ROWCOUNT
if @numrows = 0
return 0
else return 1
GO
存储过程insert_users
CREATE PROCEDURE insert_users @truename char(20), @regname char(20),@pwd char(20),@sex char(20),@email char(20),@jifen decimal(19,2)
AS
insert into users(truename,regname,pwd,sex,email,jifen) values(@truename,@regname,@pwd,@sex,@email,@jifen)
GO
在VB环境中，添加DataGrid控件，4个按钮，6个文本框
代码简单易懂。
‘引用microsoft active data object 2.X library
Option Explicit
Dim mConn As ADODB.Connection
Dim rs1 As ADODB.Recordset
Dim rs2 As ADODB.Recordset
Dim rs3 As ADODB.Recordset
Dim rs4 As ADODB.Recordset
Dim cmd As ADODB.Command
Dim param As ADODB.Parameter
'这里用第一种方法使用存储过程添加数据
Private Sub Command1_Click()
Set cmd = New ADODB.Command
Set rs1 = New ADODB.Recordset
cmd.ActiveConnection = mConn
cmd.CommandText = "insert_users"
cmd.CommandType = adCmdStoredProc
Set param = cmd.CreateParameter("truename", adChar, adParamInput, 20, Trim(txttruename.Text))
cmd.Parameters.Append param
Set param = cmd.CreateParameter("regname", adChar, adParamInput, 20, Trim(txtregname.Text))
cmd.Parameters.Append param
Set param = cmd.CreateParameter("pwd", adChar, adParamInput, 20, Trim(txtpwd.Text))
cmd.Parameters.Append param
Set param = cmd.CreateParameter("sex", adChar, adParamInput, 20, Trim(txtsex.Text))
cmd.Parameters.Append param
Set param = cmd.CreateParameter("email", adChar, adParamInput, 20, Trim(txtemail.Text))
cmd.Parameters.Append param
‘下面的类型需要注意，如果不使用adSingle,会发生一个精度无效的错误
Set param = cmd.CreateParameter("jifen", adSingle, adParamInput, 50, Val(txtjifen.Text))
cmd.Parameters.Append param
Set rs1 = cmd.Execute
Set cmd = Nothing
Set rs1 = Nothing
End Sub
'这里用第二种方法使用存储过程添加数据
Private Sub Command2_Click()
Set rs2 = New ADODB.Recordset
Set cmd = New ADODB.Command
cmd.ActiveConnection = mConn
cmd.CommandText = "insert_users"
cmd.CommandType = adCmdStoredProc
cmd.Parameters("@truename") = Trim(txttruename.Text)
cmd.Parameters("@regname") = Trim(txtregname.Text)
cmd.Parameters("@pwd") = Trim(txtpwd.Text)
cmd.Parameters("@sex") = Trim(txtsex.Text)
cmd.Parameters("@email") = Trim(txtemail.Text)
cmd.Parameters("@jifen") = Val(txtjifen.Text)
Set rs2 = cmd.Execute
Set cmd = Nothing
Set rs1 = Nothing
End Sub
'这里用第三种方法使用连接对象来插入数据
Private Sub Command4_Click()
Dim strsql As String
strsql = "insert_users '" & Trim(txttruename.Text) & "','" & Trim(txtregname.Text) & "','" & Trim(txtpwd.Text) & "','" & Trim(txtsex.Text) & "','" & Trim(txtemail.Text) & "','" & Val(txtjifen.Text) & "'"
Set rs3 = New ADODB.Recordset
Set rs3 = mConn.Execute(strsql)
Set rs3 = Nothing
End Sub
'利用存储过程显示数据
‘要处理多种参数，输入参数，输出参数以及一个直接返回值
Private Sub Command3_Click()
Set rs4 = New ADODB.Recordset
Set cmd = New ADODB.Command
cmd.ActiveConnection = mConn
cmd.CommandText = "select_users"
cmd.CommandType = adCmdStoredProc
'返回值
Set param = cmd.CreateParameter("RetVal", adInteger, adParamReturnValue, 4)
cmd.Parameters.Append param
'输入参数
Set param = cmd.CreateParameter("regname", adChar, adParamInput, 20, Trim(txtregname.Text))
cmd.Parameters.Append param
'输出参数
Set param = cmd.CreateParameter("numrows", adInteger, adParamOutput)
cmd.Parameters.Append param
Set rs4 = cmd.Execute()
If cmd.Parameters("RetVal").Value = 1 Then
MsgBox cmd.Parameters("numrows").Value
Else
MsgBox "没有记录"
End If
MsgBox rs4.RecordCount
Set DataGrid1.DataSource = rs4
DataGrid1.Refresh
End Sub
'连接数据库
Private Sub Form_Load()
Set mConn = New Connection
mConn.ConnectionString = "Provider=SQLOLEDB.1;Persist Security Info=False;User ID=sa;Initial Catalog=Test;Data Source=yang"
mConn.CursorLocation = adUseClient '设置为客户端
mConn.Open
End Sub
'关闭数据连接
Private Sub Form_Unload(Cancel As Integer)
mConn.Close
Set mConn = Nothing
End Sub
