DataGridView查詢資料

機房收費中查詢記錄，肯定會用到datagridview，下面是我實現的乙個小功能：查詢學生上機記錄。

一、時序圖

二、**

u層

public class frmonlinequery

private sub btnquery_click(sender as object, e as eventargs) handles btnquery.click
dim offlinemodel as new offlinemodel
dim onlinequerybll as new onlinequerybll
dim strresult as string
dim strcardno as string
strcardno = trim(txtcardno.text)
strresult = onlinequerybll.i***it(strcardno)
select case strresult
case "卡號不存在"
msgbox("卡號不存在")
datagridview1.datasource = vbnull
txtcardno.text = ""
case "卡號存在"
dim table as new datatable
table = onlinequerybll.getdata(strcardno)
datagridview1.autogeneratecolumns = false
datagridview1.datasource = table
datagridview1.refresh()
end select
end sub

public class onlinequerybll

public function i***it(byval strcardno as string) as string
dim onlinequerydal as new onlinequerydal
dim offlinemodel as new offlinemodel
if onlinequerydal.i***it(strcardno) = false then
return ("卡號不存在")
else
return "卡號存在"
end if
end function
public function getdata(byval strcardno as string) as datatable
dim onlinequerydal as new onlinequerydal
dim datatable as new datatable
datatable = onlinequerydal.getdata(strcardno)
return datatable
end function
end class

imports model

imports system.data.sqlclient
imports system.data.datatable
public class onlinequerydal
''' ''' 判斷卡號是否存在
''' 
''' 
''' 
''' 
public function i***it(byval strcardno as string) as boolean
dim sqlconnection1 as sqlclient.sqlconnection '執行資料庫連線
dim cmd as sqlclient.sqlcommand '使用command物件執行命令並返回
sqlconnection1 = new sqlclient.sqlconnection(con)
cmd = sqlconnection1.createcommand() '建立插入命令
cmd.commandtext = "select * from t_offline where cardno=@cardno "
cmd.commandtype = commandtype.text
cmd.parameters.add(new sqlclient.sqlparameter("@cardno", strcardno))
sqlconnection1.open()
dim reader as sqldatareader
reader = cmd.executereader()
if reader.read() then
return true
else
return false
end if
end function
''' ''' 從下機表中獲取資料
''' 
''' 卡號
''' 
''' 
public function getdata(byval strcardno as string) as datatable
dim adapter as sqldataadapter
adapter = new sqldataadapter("select * from t_offline where cardno= '" & strcardno & "'", con)
dim cmdbuilder as new sqlcommandbuilder(adapter)
dim table as new datatable
table.locale = system.globalization.cultureinfo.invariantculture
adapter.fill(table)
return table
end function
end class

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