Addition, deletion, modification and query of sqlhelper

Hello everyone , I meet you again , I'm the king of the whole stack .

When a thing is done repeatedly . You will want to find a way to replace yourself to do this repeated action .

It's the same with tapping code .

In the program . For the repeated part . The assumption is exactly the same , Then we will think of writing it as a method （ The process 、 function ）, Put it in a place that can be obtained by anyone who needs permission .

Suppose the demander is in the same project . Then write this method as a class . Suppose the demanders are in the same category . Then create a separate method in this class to write it . Abstract the same thing . For multiple users , Is to use abstract ideas .

No matter what a system , Will involve data transmission 、 operation . The operation of data is nothing more than adding, deleting, modifying and checking （CURD）, Today's system with the increase of users , More and more users operate , Big data operates frequently .

Suppose we use the original way to write . Complex systems will cause a lot of redundant code .

Add two references above the class ：

Imports System.Data.SqlClient       ' quote SQL Database connection 
Imports System.Configuration        ' Reference profile 

Copy

Set up an operation database SQLHelper class ,

Public Class SQLHelper

    ' Get the connection string in the configuration file 
    Private ReadOnly strSQLConnection As String = ConfigurationManager.AppSettings("sqlConcectStr")
    ' Define connections 
    Dim connSQL As SqlConnection = New SqlConnection(strSQLConnection)
    ' Definition cmd command 
    Dim cmdSQL As New SqlCommand
    '     ///<summary>
    '     ///depiction:< The method is sqlhelper Class initialization >
    '     ///</summary>
    Public Sub New()
        connSQL = New SqlConnection(strSQLConnection)
    End Sub


    ''    ///<summary>
    ''    ///depiction:< The method is to close the connection to the database >
    ''    ///<summary>
    Private Sub CloseSQLConnection()
        ' Infer whether the database connection object state is disconnected . The assumption is not broken , The disconnect 
        If connSQL.State <> ConnectionState.Closed Then
            connSQL.Close()
        End If
    End Sub


    '     ///<summary>
    '     ///depiction:< The method is to close the database command >
    '     ///</summary>
    Private Sub CloseSQLCommand()
        ' Suppose the command exists . Then close 
        If Not IsNothing(cmdSQL) Then
            cmdSQL.Dispose()   ' Destroy order 
            cmdSQL = Nothing
        End If
    End Sub


    '///<summary>
    ''// Run the three operations of adding, deleting and modifying .（ Ginseng ） The return value is Boolean type , Confirm whether the operation is successful 
    '///</summary>
    '   ///<param name="strSql"> You need to run the statement . Usually Sql sentence , There are also stored procedures </param>
    '   ///<param name="cmdType"> infer Sql Type of statement , Generally, it is not a stored procedure </param>
    '   ///<returns>
    '   ///< return Boolean, Success for true. Otherwise false>
    '   ///</returns>
    Public Function ExecuteAddDelUpdate(ByVal strSql As String, ByVal cmdType As CommandType, ByVal sqlParams As SqlParameter()) As Boolean
        ' Fill the class's own... With the passed parameters cmd object 
        cmdSQL.Parameters.AddRange(sqlParams)   ' Parameter incoming 
        cmdSQL.CommandType = cmdType            '
        cmdSQL.Connection = connSQL             ' Connect 
        cmdSQL.CommandText = strSql             ' Query statement 

        Try
            connSQL.Open()                     ' Open the connection 
            Return cmdSQL.ExecuteNonQuery()    ' operation 
            cmdSQL.Parameters.Clear()          ' Clear parameters 
        Catch ex As Exception
            Return False
        Finally
            Call CloseSQLConnection()          ' Close the connection 
            Call CloseSQLCommand()             ' Closing order 
        End Try

    End Function


    '///<summary>
    '/// Run the three operations of adding, deleting and modifying ,（ No reference ） The return value is Boolean type , Confirm whether the operation is successful 
    ''///</summary>
    '///<param name="strSql"> You need to run the statement . Usually Sql sentence , There are also stored procedures </param>
    '   ///<returns>
    '        ///< return Boolean type . Success for true, Otherwise false>
    '///</returns>
    Public Function ExecuteAddDelUpdate(ByVal strSql As String, ByVal cmdType As CommandType) As Boolean
        ' Fill the class's own... With the passed parameters cmd object 
        cmdSQL.CommandType = cmdType         ' take 
        cmdSQL.Connection = connSQL          ' Establishing a connection 
        cmdSQL.CommandText = strSql          ' Set query statement 


        Try
            connSQL.Open()                   ' Open the connection 
            Return cmdSQL.ExecuteNonQuery()  ' return sql Number of rows affected after running 
        Catch ex As Exception
            Return False
        Finally
            Call CloseSQLConnection()          ' Close the connection 
            Call CloseSQLCommand()             ' Closing order 
        End Try


    End Function

    '///<summary>
    ''/// Run the query operation ,（ Ginseng ） The return value is DataTable type 
    '///</summary>
    '    ///<param name="strSql"> You need to run the statement . Usually Sql sentence . There are also stored procedures </param>
    ''   ///<param name="cmdType"> infer Sql Type of statement . Generally, it is not a stored procedure </param>
    '    ///<returns>
    '         ///< Go back to the table >
    '    ///</returns>
    Public Function ExecuteSelect(ByVal strSql As String, ByVal cmdType As CommandType, ByVal sqlParams As SqlParameter()) As DataTable
        Dim sqlAdapter As SqlDataAdapter
        Dim dtSQL As New DataTable
        Dim dsSQL As New DataSet

        ' Fill the class's own... With the passed parameters cmd object 
        cmdSQL.Parameters.AddRange(sqlParams)      ' Pass in parameters 
        cmdSQL.CommandType = cmdType
        cmdSQL.Connection = connSQL                ' Establishing a connection 
        cmdSQL.CommandText = strSql                ' Query statement 

        sqlAdapter = New SqlDataAdapter(cmdSQL)    ' Instantiation Adapter

        Try
            sqlAdapter.Fill(dsSQL)               ' use Adater take DataSet fill 
            dtSQL = dsSQL.Tables(0)              'DataTable by DataSet The first table of 
            cmdSQL.Parameters.Clear()            ' Clear parameters 
        Catch ex As Exception
            MsgBox(" The query fails ", CType(vbOKOnly + MsgBoxStyle.Exclamation, MsgBoxStyle), " Warning ")
        Finally
            Call CloseSQLCommand()
        End Try

        Return dtSQL

    End Function


    '///<summary>
    ''// Run the query operation ,（ No reference ） The return value is DataTable type 
    ''</summary>
    '    ///<param name="strSql"> You need to run the statement , Usually Sql sentence , There are also stored procedures </param>
    '    ///<param name="cmdType"> infer Sql Type of statement , Generally, it is not a stored procedure </param>
    '    ///<returns>
    '       ///< Go back to the table >
    '    ///</returns>
    Public Function ExecuteSelect(ByVal strSql As String, ByVal cmdType As CommandType) As DataTable
        Dim sqlAdapter As SqlDataAdapter
        Dim dtSQL As New DataTable
        Dim dsSQL As New DataSet

        ' Fill the class's own... With the passed parameters cmd object 
        cmdSQL.CommandText = strSql
        cmdSQL.CommandType = cmdType
        cmdSQL.Connection = connSQL
        sqlAdapter = New SqlDataAdapter(cmdSQL)         ' Instantiation Adapter

        Try
            sqlAdapter.Fill(dsSQL)                      ' use Adaper take DataSet fill 
            dtSQL = dsSQL.Tables(0)                     'DataTable by DataSet The first table of 
        Catch ex As Exception
            MsgBox(" The query fails ", CType(vbOKOnly + MsgBoxStyle.Exclamation, MsgBoxStyle), " Warning ")
        Finally
            Call CloseSQLCommand()
        End Try

        Return dtSQL

    End Function

End Class

Copy

Publisher ： Full stack programmer stack length , Reprint please indicate the source ：https://javaforall.cn/116442.html Link to the original text ：https://javaforall.cn