ASP.NET 注册页面检验用户名是否存在的代码怎么写？

写一个验证函数

private bool Is_Exist()

{string Constring = "Provider=SQLOLEDBData Source=.Integrated Security=SSPIInitial Catalog=shopingdb"

OleDbConnection conn = new OleDbConnection(Constring)

string sql = "select * from users where userName='"

sql += txb_name.Text.Trim() + "'"

OleDbCommand cmd = new OleDbCommand(sql, conn)

OleDbDataReader dr

conn.Open()

dr = cmd.ExecuteReader()

if (dr.Read())

{

txb_name.Text = ""

return true

}

else

return false

}

再在button中写代码

protected void LinkButton8_Click(object sender, EventArgs e)

{

if(!Is_Exist())

{

//不存在该用户，可注册

}

else//存在返回

{

}

}

if user="" then

response.write "<SCRIPT language=JavaScript>alert('用户名不能为空 或 输入字符非法！')"

response.write "this.location.href='vbscript:history.back()'</SCRIPT>"

response.end

end if

if password="" then

response.write "<SCRIPT language=JavaScript>alert('密码不能为空 或 输入字符非法！')"

response.write "this.location.href='vbscript:history.back()'</SCRIPT>"

response.end

end if。。。。

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