Download Imports System Imports System.Data `Imports System.Data.Types

Imports System
Imports System.Data
'Imports System.Data.Types
Imports System.Configuration
Imports System.Data.SqlClient
Public Class DataBaseAccess
' Represents an open connection to a SQL database
Protected SqlCon As SqlConnection
' Represents a SQL statement or stored
' procedure to execute against a SQL database
Protected SqlCom As SqlCommand
' Provides a way of reading a forward-only
' stream of rows from a SQL database
Protected Sqldreader As SqlDataReader
' Represents a set of data commands and a database
' connection that are used to fill the
Protected SqlDa As SqlDataAdapter
' Automatically generates single-table commands that are
' used to reconcile changes made to a
Protected SqlComb As SqlCommandBuilder
Private ConnectionString As String
'Purpose: Class constructor.
Public Sub New()
'Initialize the class' members.
SqlCon = New SqlConnection
' Set connection string of the SqlConnection object
SqlCon.ConnectionString = ConnectionString
End Sub
' Purpose: Opens a database connection
' if SQL connection open successful then return true
' else occur exception return false
Public Function OpenConnection() As Boolean
Try ' open connection
If SqlCon.State <> ConnectionState.Open Then
SqlCon.ConnectionString = ConnectionString
SqlCon.Open()
Return True
Else
Return False
End If
Catch ex As SqlException
MessageBox.Show("Can not connect to database, please choose a database!", "Connect Error",
MessageBoxButtons.OK, MessageBoxIcon.Error)
End Try
Return True
End Function
' Purpose: Close a database connection.
' if SQL connection close successful then return true else
' occur exception return false
Protected Function CloseConnection() As Boolean
Try ' Close connection
If SqlCon.State <> ConnectionState.Closed Then
SqlCon.Close()
Return True
Else
Return False
End If
Catch ex As SqlException
MsgBox(ex.Message, MsgBoxStyle.Critical, "Close Database")
Return False
End Try
End Function
' Purpose: ExecuteNoneQuery command
' if SQL statement execute successful then return true else
' occur exception retun false
Public Function ExecuteNoneQuery(ByVal v_sSqlString As String, Optional ByVal ShowErrorMessage As
Boolean = False) As Boolean
If OpenConnection() Then
Try
'sets the SqlConnection used by this SqlCom of the SqlCommand
SqlCom = New SqlCommand(v_sSqlString, SqlCon)
' Executes a SQL statement against the connection and returns
' the number of rows affected.
SqlCom.ExecuteNonQuery()
Return True
Catch ex As SqlException
If ShowErrorMessage Then
MsgBox(ex.Message, MsgBoxStyle.Critical, "Execute!")
End If
Return False
Finally
' Close database connection.
CloseConnection()
SqlCom.Dispose()
End Try
End If
Return True
End Function
' Purpose: Provides a way of reading a forward-only stream of rows from a SQL database
' if SQL statement execute successful then return SqlDataReader else
' occur exception return nothing
Public Function GetDataReader(ByVal v_sSqlString As String) As SqlDataReader
Try
If OpenConnection() Then
'sets the SqlConnection used by this SqlCom of the SqlCommand
SqlCom = New SqlCommand(v_sSqlString, SqlCon)
' Sends the CommandText to the Connection and builds a SqlDataReader.
Sqldreader = SqlCom.ExecuteReader
End If
Return Sqldreader
Catch ex As SqlException
MsgBox(ex.Message, MsgBoxStyle.Critical, "Get DataReader")
Return Nothing
Finally
' Close database connection.
CloseConnection()
SqlCom.Dispose()
End Try
End Function
'Purpose: return the first column of the first row in the result set,
' or a nothing reference if the result set is empty
Public Function GetScalar(ByVal v_sSqlString As String) As Object
Dim Result As Object = Nothing
Try
If OpenConnection() Then
'sets the SqlConnection used by this SqlCom of the SqlCommand
SqlCom = New SqlCommand(v_sSqlString, SqlCon)
' Executes the query, and returns the first column of the first row in the
' result set returned by the query. Extra columns or rows are ignored.
Result = SqlCom.ExecuteScalar
End If
Catch ex As Exception
MsgBox(ex.Message, MsgBoxStyle.Critical, "Get Scalar")
Finally
' Close database connection.
CloseConnection()
SqlCom.Dispose()
End Try
Return Result
End Function
' Purpose: Return one table of in-memory data.
Public Function GetDataTable(ByVal v_sSqlString As String) As DataTable
Dim sTableName As String = String.Empty
Try
sTableName = v_sSqlString.Substring(14)
sTableName = sTableName.Substring(0, sTableName.IndexOf(" ") + 1)
Catch ex As Exception
End Try
Dim dtable As New DataTable(sTableName)
SqlDa = New SqlDataAdapter(v_sSqlString, SqlCon)
If OpenConnection() Then
Try
' Configures the schema to match that in the data source based on
' the specified System.Data.SchemaType
'SqlDa.FillSchema(dtable, SchemaType.Source)
SqlDa.Fill(dtable)
Catch ex As SqlException
MsgBox(ex.Message, MsgBoxStyle.Critical, "Get Datatable")
Finally
' Close database connection.
CloseConnection()
SqlDa.Dispose()
End Try
End If
Return dtable
End Function
Public Function GetDataTable(ByVal TableName As String, ByVal Condition As String) As DataTable
Dim dtable As New DataTable(TableName)
SqlDa = New SqlDataAdapter("Select * from " & TableName & " Where " & Condition, SqlCon)
If OpenConnection() Then
Try
SqlDa.Fill(dtable)
Catch ex As SqlException
MsgBox(ex.Message, MsgBoxStyle.Critical, "Get DataTable")
Finally
' Close database connection.
CloseConnection()
SqlDa.Dispose()
End Try
End If
Return dtable
End Function
' Calls the respective INSERT, UPDATE, or DELETE statements for each inserted,
' updated, or deleted row in the specified DataTable. if execute success
' return true else return false
Public Function UpdateDataTable(ByVal v_sSqlString As String, ByVal v_dtable As _
System.Data.DataTable, Optional ByVal ShowErrorMessage As Boolean = False) As Boolean
SqlDa = New SqlDataAdapter
SqlDa.SelectCommand = New SqlCommand(v_sSqlString, SqlCon)
' Without the SQLCommandBuilder this line would fail.
SqlComb = New SqlCommandBuilder(SqlDa)
Try
If OpenConnection() Then
SqlDa.Update(v_dtable)
Return True
Else
Return False
End If
Catch ex As Exception
If ShowErrorMessage Then
MsgBox(ex.Message, MsgBoxStyle.Critical, "Warning")
End If
Return False
Finally
' Close database connection.
CloseConnection()
SqlDa.Dispose()
SqlComb.Dispose()
End Try
End Function
'Purpose: Implements the IDispose' method Dispose.
Protected Overloads Sub Dispose()
CloseConnection()
GC.SuppressFinalize(Me)
End Sub
End Class