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vb.net 中如何使用SQL語句查詢數(shù)據(jù)庫中的數(shù)據(jù)
1、首先打開Visual Studio 2008代碼窗口，添加引用。
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2、輸入以下代碼：Public conn1 ?As SqlConnection = New SqlConnection 。
3、聲明關(guān)鍵字 Public；（因?yàn)槭侨肿兞?，所以用Public 來聲明）。
4、如果SQL 數(shù)據(jù)庫就在本機(jī)，則用以下代碼連接。
5、如果代碼太長，影響可讀性，可以用空格加"_"后，回車換行即可。
使用VB.net實(shí)現(xiàn)sql數(shù)據(jù)庫的備份與恢復(fù)代碼
Private Sub Button _Click(ByVal sender As System Object ByVal e As System EventArgs) Handles Button Click 備份數(shù)據(jù)庫 BACKUP DATABASE Test TO DISK= C:\Backup WITH Format Dim cn As SqlConnection Dim cm As SqlCommand cn = getDB() cm = New SqlCommand( BACKUP DATABASE JXbase TO DISK= C:\Backup WITH Format cn) cn Open() cm ExecuteNonQuery() MsgBox( 備份成功 ) cn Close()
End Sub
恢復(fù) Private Sub Button _Click(ByVal sender As System Object ByVal e As System EventArgs) Handles Button Click Dim cn As New SqlConnection Dim cn As New SqlConnection Dim mydr As SqlDataReader Dim str As String
Dim tmpConnectionString As String = Data Source=JJK;Initial Catalog=master;Integrated Security=True cn ConnectionString = tmpConnectionString cn ConnectionString = tmpConnectionString cn Open() cn Open() Dim cm As SqlCommand = New SqlCommand( select spid from master sysprocesses where dbid=db_id( JXbase ) cn) mydr = cm ExecuteReader()
Dim cm As SqlCommand = New SqlCommand() cm Connection = cn
While (mydr Read()) 殺死進(jìn)程
str = kill mydr( spid ) ToString() cm CommandText = str cm CommandType = CommandType Text Application DoEvents() cm ExecuteNonQuery() 殺進(jìn)程 End While mydr Close() cm = New SqlCommand( RESTORE DATABASE JXbase FROM DISK= C:\Backup cn) 恢復(fù)備份 cm ExecuteNonQuery() MsgBox( 恢復(fù)成功成功 ) cn Close() cn Close()
lishixinzhi/Article/program/net/201311/12901
vb.net 怎么操作數(shù)據(jù)庫
如果樓主熟悉VB6，可以直接在項(xiàng)目中添加ADODB的Com引用，這樣你就可以像VB6那樣操作數(shù)據(jù)庫了！
另外
.NET
Framework中連接數(shù)據(jù)庫要用到ADO.NET。如果要操作Access數(shù)據(jù)庫，要用到System.Data.OleDb命名空間下的許多類。
比如按樓主所說，“我想在textbox1中顯示表一中【一些數(shù)據(jù)】字段下的第一個內(nèi)容”：
'首先導(dǎo)入命名空間
Imports
System.Data
Imports
System.Data.OleDb
'然后在某一個事件處理程序中寫：
Dim
conn
As
New
OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data
Source=數(shù)據(jù)庫.accdb;Jet
OLEDB:Database
Password=MyDbPassword")
Dim
command
As
New
OleDbCommand("Select
*
From
數(shù)據(jù)表",
conn)
conn.Open()
'打開數(shù)據(jù)庫連接
Dim
reader
As
OleDbDataReader
=
command.ExecuteReader()
'執(zhí)行SQL語句，返回OleDbDataReader
對象
Do
While
reader.Read()
'讀取一條數(shù)據(jù)
textbox1.Text
+=
reader("一些數(shù)據(jù)")
VbCrLf
Loop
reader.Close()
'關(guān)閉OleDbDataReader
conn.Close()
'關(guān)閉連接
vb.net數(shù)據(jù)庫操作
參考一下下面這段代碼就可以了。
Imports System.Data
'引入數(shù)據(jù)庫操作類命名空間
Imports System.Data.OleDb
'引入ADO.NET操作命名空間
Public Class FrmModifystInfo
Inherits System.Windows.Forms.Form
Public ADOcmd As OleDbDataAdapter
Public ds As DataSet = New DataSet()
'建立DataSet對象
Public mytable As Data.DataTable
'建立表單對象
Public myrow As Data.DataRow
'建立數(shù)據(jù)行對象
Public rownumber As Integer
'定義一個整型變量來存放當(dāng)前行數(shù)
Public SearchSQL As String
Public cmd As OleDbCommandBuilder
'======================================================
#Region " Windows 窗體設(shè)計器生成的代碼 "
#End Region
'======================================================
Private Sub FrmModifystInfo_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.Load
'窗體的載入
TxtSID.Enabled = False
TxtName.Enabled = False
ComboSex.Enabled = False
TxtBornDate.Enabled = False
TxtClassno.Enabled = False
TxtRuDate.Enabled = False
TxtTel.Enabled = False
TxtAddress.Enabled = False
TxtComment.Enabled = False '設(shè)置信息為只讀
Dim tablename As String = "student_Info "
SearchSQL = "select * from student_Info "
ExecuteSQL(SearchSQL, tablename) '打開數(shù)據(jù)庫
ShowData() '顯示記錄
End Sub
Private Sub ShowData()
'在窗口中的textbox中顯示數(shù)據(jù)
myrow = mytable.Rows.Item(rownumber)
TxtSID.Text = myrow.Item(0).ToString
TxtName.Text = myrow.Item(1).ToString
ComboSex.Text = myrow.Item(2).ToString
TxtBornDate.Text = Format(myrow.Item(3), "yyyy-MM-dd ")
TxtClassno.Text = myrow.Item(4).ToString
TxtTel.Text = myrow.Item(5).ToString
TxtRuDate.Text = Format(CDate(myrow.Item(6)), "yyyy-MM-dd ")
TxtAddress.Text = myrow.Item(7).ToString
TxtComment.Text = myrow.Item(8).ToString
End Sub
Private Sub BtFirst_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtFirst.Click
'指向第一條數(shù)據(jù)
rownumber = 0
ShowData()
End Sub
Private Sub BtPrev_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtPrev.Click
'指向上一條數(shù)據(jù)
BtNext.Enabled = True
rownumber = rownumber - 1
If rownumber 0 Then
rownumber = 0 '如果到達(dá)記錄的首部，行號設(shè)為零
BtPrev.Enabled = False
End If
ShowData()
End Sub
Private Sub BtNext_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtNext.Click
'指向上一條數(shù)據(jù)
BtPrev.Enabled = True
rownumber = rownumber + 1
If rownumber mytable.Rows.Count - 1 Then
rownumber = mytable.Rows.Count - 1 '判斷是否到達(dá)最后一條數(shù)據(jù)
BtNext.Enabled = False
End If
ShowData()
End Sub
Private Sub BtLast_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtLast.Click
'指向最后一條數(shù)據(jù)
rownumber = mytable.Rows.Count - 1
ShowData()
End Sub
Private Sub BtDelete_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtDelete.Click
mytable.Rows.Item(rownumber).Delete() '刪除記錄
If MsgBox( "確定要刪除改記錄嗎？ ", MsgBoxStyle.OKCancel + vbExclamation, "警告 ") = MsgBoxResult.OK Then
cmd = New OleDbCommandBuilder(ADOcmd)
'使用自動生成的SQL語句
ADOcmd.Update(ds, "student_Info ")
BtNext.PerformClick()
End If
End Sub
Private Sub BtModify_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtModify.Click
TxtSID.Enabled = False '關(guān)鍵字段只讀
TxtName.Enabled = True '可讀寫
ComboSex.Enabled = True
TxtBornDate.Enabled = True
TxtClassno.Enabled = True
TxtRuDate.Enabled = True
TxtTel.Enabled = True
TxtAddress.Enabled = True
TxtComment.Enabled = True
End Sub
Private Sub BtUpdate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtUpdate.Click
If Not Testtxt(TxtName.Text) Then
MsgBox( "請輸入姓名！ ", vbOKOnly + vbExclamation, "警告 ")
TxtName.Focus()
Exit Sub
End If
If Not Testtxt(ComboSex.Text) Then
MsgBox( "請選擇性別！ ", vbOKOnly + vbExclamation, "警告 ")
ComboSex.Focus()
Exit Sub
End If
If Not Testtxt(TxtClassno.Text) Then
MsgBox( "請選擇班號！ ", vbOKOnly + vbExclamation, "警告 ")
TxtClassno.Focus()
Exit Sub
End If
If Not Testtxt(TxtTel.Text) Then
MsgBox( "請輸入聯(lián)系電話！ ", vbOKOnly + vbExclamation, "警告 ")
TxtTel.Focus()
Exit Sub
End If
If Not Testtxt(TxtAddress.Text) Then
MsgBox( "請輸入家庭住址！ ", vbOKOnly + vbExclamation, "警告 ")
TxtAddress.Focus()
Exit Sub
End If
If Not IsNumeric(Trim(TxtSID.Text)) Then
MsgBox( "請輸入數(shù)字學(xué)號！ ", vbOKOnly + vbExclamation, "警告 ")
Exit Sub
TxtSID.Focus()
End If
If Not IsDate(TxtBornDate.Text) Then
MsgBox( "出生時間應(yīng)輸入日期格式（yyyy-mm-dd）！ ", vbOKOnly + vbExclamation, "警告 ")
Exit Sub
TxtBornDate.Focus()
End If
If Not IsDate(TxtRuDate.Text) Then
MsgBox( "入校時間應(yīng)輸入日期格式（yyyy-mm-dd）！ ", vbOKOnly + vbExclamation, "警告 ")
TxtRuDate.Focus()
Exit Sub
End If
myrow.Item(0) = Trim(TxtSID.Text)
myrow.Item(1) = Trim(TxtName.Text)
myrow.Item(2) = Trim(ComboSex.Text)
myrow.Item(3) = Trim(TxtBornDate.Text)
myrow.Item(4) = Trim(TxtClassno.Text)
myrow.Item(5) = Trim(TxtTel.Text)
myrow.Item(6) = Trim(TxtRuDate.Text)
myrow.Item(7) = Trim(TxtAddress.Text)
myrow.Item(8) = Trim(TxtComment.Text)
mytable.GetChanges()
cmd = New OleDbCommandBuilder(ADOcmd)
'使用自動生成的SQL語句
ADOcmd.Update(ds, "student_Info ")
'對數(shù)據(jù)庫進(jìn)行更新
MsgBox( "修改學(xué)籍信息成功！ ", vbOKOnly + vbExclamation, "警告 ")
TxtName.Enabled = False
ComboSex.Enabled = False
TxtBornDate.Enabled = False
TxtClassno.Enabled = False
TxtRuDate.Enabled = False
TxtTel.Enabled = False
TxtAddress.Enabled = False
TxtComment.Enabled = False '重新設(shè)置信息為只讀
End Sub
Private Sub BtCancel_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtCancel.Click
TxtSID.Enabled = False
TxtName.Enabled = False
ComboSex.Enabled = False
TxtBornDate.Enabled = False
TxtClassno.Enabled = False
TxtRuDate.Enabled = False
TxtTel.Enabled = False
TxtAddress.Enabled = False
TxtComment.Enabled = False
End Sub
Public Function ExecuteSQL(ByVal SQL As String, ByVal table As String)
Try
'建立ADODataSetCommand對象
'數(shù)據(jù)庫查詢函數(shù)
ADOcmd = New OleDbDataAdapter(SQL, "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=c:\student.mdb ")
'建立ADODataSetCommand對象
ADOcmd.Fill(ds, table) '取得表單
mytable = ds.Tables.Item(0) '取得名為table的表
rownumber = 0 '設(shè)置為第一行
myrow = mytable.Rows.Item(rownumber)
'取得第一行數(shù)據(jù)
Catch
MsgBox(Err.Description)
End Try
End Function
End Class
文章名稱：關(guān)于vb.net使用數(shù)據(jù)庫的信息
標(biāo)題來源：http://www.dlmjj.cn/article/ddopjcs.html
