Question

必须声明标量变量 "@UserID".请问怎样解决

Answer 1

问题出在OleDb和SqlClient 两种Sql参数占位符语法不一样，SqlClient用@代表参数
string str = "select * from user where UserID=@UserID"
而在OleDb中应写成
string str = "select * from user where UserID=?"

然后在OleDbParameter传参中new OleDbParameter[] { new OleDbParameter("@P1", OleDbType.Integer, 4) };