'以下是把数据库的数据保存为xml格式
dataset1 = new dataset
oledbdataadapter1 = new oledbdataadapter("select * from users", oledbconnection1)
oledbdataadapter1.fill(dataset1, "users")
dataset1.writexml("myxml.xml")
end if
catch ex as exception
listbox1.items.add("errors!")
end try
oledbconnection1.close()
else
messagebox.show("请输入完整!!")
end if
//==================接下来是对数据库进行查询===================
'双击"查找"按钮
'写入以下代码
if textbox4.text <> "" then
'还是和上面一样如果文本框为空，就不执行，如果不为空，就执行下面的操作
listbox1.items.clear()
'首先把listbox清空
dim searchtext as string
searchtext = textbox4.text
oledbconnection1.open()
dim selstring as string
selstring = "select * from users where nameid like '%" & searchtext & "%'"
' 建立查询字符串，可以支持模糊查询
oledbcommand1 = new oledbcommand
me.oledbcommand1.commandtext = selstring
me.oledbcommand1.connection = oledbconnection1
'以下几句是显示匹配的条数
dataset1 = new dataset
oledbdataadapter1 = new oledbdataadapter(selstring, oledbconnection1)
oledbdataadapter1.fill(dataset1, "users")
listbox1.items.add("共有" & dataset1.tables("users").rows.count & "条匹配的记录")
listbox1.items.add("-------------------------------------------------------------")
try
'进行异常处理
dim cmdreader as oledbdatareader = oledbcommand1.executereader()
while cmdreader.read
'注意这里要用while
'不然就无法进行循环，就只能进行一次查询
listbox1.items.add(cmdreader("nameid").tostring())
listbox1.items.add(cmdreader("age").tostring())
listbox1.items.add(cmdreader("faverity").tostring())
listbox1.items.add("----------------------------------")
end while
cmdreader.close()
