VB.NET机房收费系统SQLHelper

1直在用SQLHelper，但是直到现在才稍稍明白1点数据连接类的妙用 真实的体现了代码重复利用。

SQL 语句的 更新 插入 查找 删除
包括有参数的、无参数的更新 插入 查找 删除 都包括了

下面是代码的详细解释，现在先看看明白，等到以后写的时候就方便多了。

“`
Imports System.Data
Imports System.Data.SqlClient
Imports System.Configuration ‘必须要在管理器中添加援用
”’
”’ SqlHelper类是专门提供给广大用户用于高性能、可升级和最好练习的sql数据操作
”’
”’
Public Class SqlHelper
‘定义变量
‘取得数据库的连接字符串
Private ReadOnly strConnection As String = ConfigurationManager.AppSettings(“ConnStr”)
‘设置连接
Dim conn As SqlConnection = New SqlConnection(strConnection)
‘定义cmd命令
Dim cmd As New SqlCommand

''' <summary>  
''' 履行增删改3个操作,(有参)返回值为Boolean类型,确认是不是履行成功  
''' </summary>  
''' <param name="cmdText">需要履行语句,1般是Sql语句,也有存储进程</param>  
''' <param name="cmdType">判断Sql语句的类型,1般都不是存储进程</param>  
''' <param name="paras">参数数组,没法确认有多少参数</param>  
''' <returns></returns>  
''' <remarks></remarks>  
Public Function ExecAddDelUpdate(ByVal cmdText As String, ByVal cmdType As CommandType, ByVal paras As SqlParameter()) As Integer
    '将传入的值,分别为cmd的属性赋值  
    cmd.Parameters.AddRange(paras)   '将参数传入  
    cmd.CommandType = cmdType            '设置1个值,解释cmdText  
    cmd.Connection = conn                '设置连接,全局变量  
    cmd.CommandText = cmdText            '设置查询的语句  

    Try
        conn.Open()                      '打开连接  
        Return cmd.ExecuteNonQuery()     '履行增删改操作  
        cmd.Parameters.Clear()           '清除参数  
    Catch ex As Exception
        Return 0                         '如果出错,返回0  
    Finally
        Call CloseConn(conn)
        Call CloseCmd(cmd)
    End Try
End Function
''' <summary>  
''' 履行增删改3个操作,(无参)  
''' </summary>  
''' <param name="cmdText">需要履行语句,1般是Sql语句,也有存储进程</param>  
''' <param name="cmdType">判断Sql语句的类型,1般都不是存储进程</param>  
''' <returns>Interger,受影响的行数</returns>  
''' <remarks>2013年2月2日8:19:59</remarks>  
Public Function ExecAddDelUpdateNo(ByVal cmdText As String, ByVal cmdType As CommandType) As Integer
    '为要履行的命令cmd赋值  
    cmd.CommandText = cmdText       '先是查询的sql语句  
    cmd.CommandType = cmdType       '设置Sql语句如何解释  
    cmd.Connection = conn           '设置连接  

    '履行操作  
    Try
        conn.Open()
        Return cmd.ExecuteNonQuery()
    Catch ex As Exception
        Return 0
    Finally
        Call CloseConn(conn)
        Call CloseCmd(cmd)
    End Try
End Function

''' <summary>  
''' 履行查询的操作,(有参),参数不限  
''' </summary>  
''' <param name="cmdText">需要履行语句,1般是Sql语句,也有存储进程</param>  
''' <param name="cmdType">判断Sql语句的类型,1般都不是存储进程</param>  
''' <param name="paras">传入的参数</param>  
''' <returns></returns>  
''' <remarks></remarks>  
Public Function ExecSelect(ByVal cmdText As String, ByVal cmdType As CommandType, ByVal paras As SqlParameter()) As DataTable

    Dim sqlAdapter As SqlDataAdapter
    Dim dt As New DataTable
    Dim ds As New DataSet
    '还是给cmd赋值  
    cmd.CommandText = cmdText
    cmd.CommandType = cmdType
    cmd.Connection = conn
    cmd.Parameters.AddRange(paras)  '参数添加  
    sqlAdapter = New SqlDataAdapter(cmd)  '实例化adapter  
    Try
        sqlAdapter.Fill(ds)           '用adapter将dataSet填充   
        If ds.Tables.Count = 0 Then

        Else
            dt = ds.Tables(0)             'datatable为dataSet的第1个表  
            cmd.Parameters.Clear()        '清除参数  
        End If

    Catch ex As Exception
        MsgBox("查询失败", CType(vbOKOnly + MsgBoxStyle.Exclamation, MsgBoxStyle), "正告")
    Finally                            '最后1定要烧毁cmd  
        Call CloseCmd(cmd)
    End Try
    Return dt
End Function


''' <summary>  
''' 履行查询的操作,(无参)  
''' </summary>  
''' <param name="cmdText">需要履行语句,1般是Sql语句,也有存储进程</param>  
''' <param name="cmdType">判断Sql语句的类型,1般都不是存储进程</param>  
''' <returns>dataTable,查询到的表格</returns>  
''' <remarks></remarks>  
Public Function ExecSelectNo(ByVal cmdText As String, ByVal cmdType As CommandType) As DataTable
    Dim sqlAdapter As SqlDataAdapter
    Dim ds As New DataSet
    '还是给cmd赋值  
    cmd.CommandText = cmdText
    cmd.CommandType = cmdType
    cmd.Connection = conn
    sqlAdapter = New SqlDataAdapter(cmd)  '实例化adapter  
    Try
        sqlAdapter.Fill(ds)           '用adapter将dataSet填充   
        Return ds.Tables(0)             'datatable为dataSet的第1个表  
    Catch ex As Exception
        Return Nothing
    Finally                            '最后1定要烧毁cmd  
        Call CloseCmd(cmd)
    End Try
End Function

''' <summary>  
''' 关闭连接  
''' </summary>  
''' <param name="conn">需要关闭的连接</param>  
''' <remarks></remarks>  
Public Sub CloseConn(ByVal conn As SqlConnection)
    If (conn.State <> ConnectionState.Closed) Then  '如果没有关闭  
        conn.Close()                    '关闭连接  
        conn = Nothing                  '不指向原对象  
    End If

End Sub
''' <summary>  
''' 关闭命令  
''' </summary>  
''' <param name="cmd">需要关闭的命令</param>  
''' <remarks></remarks>  
Public Sub CloseCmd(ByVal cmd As SqlCommand)

    If Not IsNothing(cmd) Then          '如果cmd命令存在  
        cmd.Dispose()                   '烧毁  
        cmd = Nothing
    End If
End Sub
End Class

这个数据库链接类非常全面既可以查询sql语句，又可以查询视图存储进程。触发器没有试过，不知道如何？