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通用
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连接数据库（拼接连接数据库字符串，调用函数即可）：
dim con as string = "provider=microsoft.jet.oledb.4.0;data source= atm.mdb"
dim connconnection as oledb.oledbconnection = new oledb.oledbconnection
connconnection.connectionstring = con
connconnection.open()
验证用户名密码（就是拿着界面上输入的用户名密码 去数据库里面匹配，如果可以找到就通过）：
private function userisvalid() as boolean
'连接数据库
dim con as string = "provider=microsoft.jet.oledb.4.0;data source= atm.mdb"
dim connconnection as oledb.oledbconnection = new oledb.oledbconnection
connconnection.connectionstring = con
connconnection.open()
'验证一下用户名密码是否存在
dim strsql as string = "select * from accountinfo where accountno = '" & _
trim(textbox1.text) & "' and password = '" & trim(textbox2.text) & "'"
dim conncommand as oledb.oledbcommand = new oledb.oledbcommand(strsql, connconnection)
dim myreader as oledb.oledbdatareader = conncommand.executereader
'如果有数据
if myreader.hasrows then
myreader.read() '读一行数据到reader里面
if trim(textbox1.text) = myreader(1) and trim(textbox2.text) = myreader(2) then
connconnection.close()
return true
else
connconnection.close()
return false
end if
end if
connconnection.close()
'没数据直接返回错误
return false
end function
退出(其实就是把所有打开的窗口都隐藏，把登陆窗口显示就可以了)：
for each f as form in application.openforms
f.hide()
frmlogin.show()
next
====================================
客户
====================================
取款：
'连接数据库
dim con as string = "provider=microsoft.jet.oledb.4.0;data source= atm.mdb"
dim connconnection as oledb.oledbconnection = new oledb.oledbconnection
connconnection.connectionstring = con
connconnection.open()
'修改金额(存钱)
dim sql as string = "update accountinfo set balance = balance + " + textbox1.text + " where accountno = '" + frmlogin.textbox1.text + "'"
dim cmd as oledb.oledbcommand = new oledb.oledbcommand(sql, connconnection)
cmd.executenonquery()
'记录操作日志
sql = "insert into accountact (accountno,lastopt,amount) values ('" & trim(frmlogin.textbox1.text) & "','" & trim(datetime.now.tostring()) & "',
" & ctype(textbox1.text, double) & ")"
dim cmd2 as oledb.oledbcommand = new oledb.oledbcommand(sql, connconnection)
cmd2.executenonquery()
connconnection.close()
存款：
'连接数据库
dim con as string = "provider=microsoft.jet.oledb.4.0;data source= atm.mdb"
dim connconnection as oledb.oledbconnection = new oledb.oledbconnection
connconnection.connectionstring = con
connconnection.open()
'修改金额(取钱)
dim sql as string = "update accountinfo set balance = balance - " + textbox2.text + " where accountno = '" + frmlogin.textbox1.text + "'"
dim cmd as oledb.oledbcommand = new oledb.oledbcommand(sql, connconnection)
cmd.executenonquery()
'记录操作日志
sql = "insert into accountact (accountno,lastopt,amount) values ('" & trim(frmlogin.textbox1.text) & "','" & trim(datetime.now.tostring()) & "',
" & ctype(textbox1.text, integer) & ")"
cmd = new oledb.oledbcommand(sql, connconnection)
cmd.executenonquery()
connconnection.close()
查询账户：
'连接数据库
dim con as string = "provider=microsoft.jet.oledb.4.0;data source= atm.mdb"
dim connconnection as oledb.oledbconnection = new oledb.oledbconnection
connconnection.connectionstring = con
connconnection.open()
dim sql as string = "select balance from accountinfo where accountno = '" + frmlogin.textbox1.text + "'"
dim cmd as oledb.oledbcommand = new oledb.oledbcommand(sql, connconnection)
dim myreader as oledb.oledbdatareader = cmd.executereader
if myreader.hasrows then
myreader.read()
label1.text = myreader(0)
else
messagebox.show("未找到账户信息")
end if
connconnection.close()
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管理员
==================================
记录操作日志：
sql = "insert into accountact (accountno,lastopt,amount) values ('" & trim(frmlogin.textbox1.text) & "','" & trim(datetime.now.tostring()) & "',
" & ctype(textbox1.text, integer) & ")"
cmd = new oledb.oledbcommand(sql, connconnection)
cmd.executenonquery()
connconnection.close()
查看所有操作日志：
'连接数据库
dim con as string = "provider=microsoft.jet.oledb.4.0;data source= atm.mdb"
dim connconnection as oledb.oledbconnection = new oledb.oledbconnection
connconnection.connectionstring = con
connconnection.open()
'把查询的数据取出来放到data set
dim strsql as string = "select * from accountact"
dim mydataset as dataset = new dataset()
dim myadapter as oledb.oledbdataadapter = new oledb.oledbdataadapter(strsql, connconnection)
myadapter.fill(mydataset, "accountact")
connconnection.close()
'把数据从dataset中取出来显示在控件上()
datagridview1.datasource = mydataset.tables(0)
datagridview1.autosizecolumnsmode = datagridviewautosizecolumnsmode.allcells
查看所有用户账号
'连接数据库
dim con as string = "provider=microsoft.jet.oledb.4.0;data source= atm.mdb"
dim connconnection as oledb.oledbconnection = new oledb.oledbconnection
connconnection.connectionstring = con
connconnection.open()
'把查询的数据取出来放到data set
dim strsql as string = "select * from accountinfo"
dim mydataset as dataset = new dataset()
dim myadapter as oledb.oledbdataadapter = new oledb.oledbdataadapter(strsql, connconnection)
myadapter.fill(mydataset, "accountinfo")
connconnection.close()
'把数据从dataset中取出来显示在控件上()
datagridview1.datasource = mydataset.tables(0)
datagridview1.autosizecolumnsmode = datagridviewautosizecolumnsmode.allcells
以上就是vb 操作access 实例 练习题--atm取款机 代码段的内容。