datasql.vb

教务管理系统：学生成绩管理

Imports System.Data.SqlClient
Imports System.IO

Module DataSql

    Public UserFlag As Boolean '记录了是否有用户记录被添加或者修改
    Public User As String  '记录了用户管理中的主键信息
    Public UserID As String '记录了登录用户的ID信息
    Public UserRight As Int16 '记录了登录用户的权限信息

    'SqlCon是全局的数据库连接变量
    Public SqlCon As New SqlConnection("Data Source=(local);Database=STUDENT;User Id=AM;Pwd=AM")


    Public Function GetDataTable(ByVal sql As String) As DataTable
        Dim dt As New DataTable

        Try
            Dim SqlAda As New SqlDataAdapter(New SqlCommand(sql, SqlCon))
            SqlAda.Fill(dt)
        Catch ex As Exception
            WriteErr(ex)
        End Try

        Return dt
    End Function

    Public Sub WriteErr(ByVal ex As Exception)

        Dim path As String = Application.StartupPath + "\Err01.txt"
        If Not File.Exists(path) Then
            File.Create(path)
        End If
        Dim sw As StreamWriter = File.AppendText(path)
        sw.Write(System.DateTime.Now.ToString() + vbCrLf)
        sw.Write(ex.Message + vbCrLf)
        sw.Write(ex.StackTrace + vbCrLf)
        sw.Flush()
        sw.Close()

    End Sub

    '判断输入文本是否为整数
    Function JudgeInt(ByVal str As String)
        Try
            Int16.Parse(str)
            Return True
        Catch ex As Exception
            Return False
        End Try
    End Function

    '判断某数据表中某主键值是否存在
    Function JudgeKeyExist(ByVal tableName As String, ByVal key As String, ByVal keyValue As Int16)
        Dim sql = "select * from " + tableName + "  where " + key + "=" + keyValue.ToString
        Try

            Dim dt As DataTable = GetDataTable(sql)
            If dt.Rows.Count <> 0 Then
                Return True
            Else
                Return False
            End If
        Catch ex As Exception
            WriteErr(ex)
        End Try
    End Function

    Function JudgeKeyExist(ByVal tableName As String, ByVal key As String, ByVal keyValue As String)
        Dim sql = "select * from " + tableName + "  where " + key + "='" + keyValue + "'"
        Try

            Dim dt As DataTable = GetDataTable(sql)
            If dt.Rows.Count <> 0 Then
                Return True
            Else
                Return False
            End If
        Catch ex As Exception
            WriteErr(ex)
        End Try
    End Function

    Function JudgeKeyExist(ByVal tableName As String, ByVal key1 As String, ByVal keyValue1 As Int16, ByVal key2 As String, ByVal keyValue2 As Int16)
        Dim sql = "select * from " + tableName + "  where " + key1 + "=" + keyValue1.ToString + "  and " + key2 + "=" + keyValue2.ToString
        Try

            Dim dt As DataTable = GetDataTable(sql)
            If dt.Rows.Count <> 0 Then
                Return True
            Else
                Return False
            End If
        Catch ex As Exception
            WriteErr(ex)
        End Try
    End Function

    '判断传入的节点处于第几层
    Function TreeNodeLevel(ByVal node As TreeNode)

        Dim IDItem() As String
        IDItem = node.FullPath.Split("\")
        Return IDItem.Length

    End Function


End Module