检查框中的值是否已存在于数据库中 [英] Check if value in box is already in database

问题描述

我想检查标签中的值是否已存在于数据库中。可能吗？

I want to check if a value in a label is already in the database. Is it possible?

                    OleDbDataAdapter da = new OleDbDataAdapter("Select * from [Customer Orders] Where [Order ID] = '" + PrdtID.Text + "'", MAcon);
                    DataTable dtbl = new DataTable();
                    da.Fill(dtbl);

                    if (dtbl.Rows.Count == 1)
                    {
.......
}

每次我收到错误消息

Each time i get the error message of

An unhandled exception of type 'System.Data.OleDb.OleDbException' occurred in System.Data.dll

Additional information: Syntax error (missing operator) in query expression '[Order ID] = @[Order ID]'.

我的尝试：

What I have tried:

OleDbDataAdapter da = new OleDbDataAdapter("Select * from [Customer Orders] Where [Order ID] = @[Order ID]", MAcon);
DataTable dtbl = new DataTable();
da.Fill(dtbl);

推荐答案

后一个代码块中的代码似乎是一个好的开始。你缺少的是创建和设置参数的值。换句话说，比如

The code you have in the latter code block seems like a good start. what you're missing is creating and setting the value of a parameter. In other words something like

OleDbDataAdapter da = new OleDbDataAdapter("Select * from [Customer Orders] Where [Order ID] = @OrderID", MAcon);
da.SelectCommand.Parameters.AddWithValue("@OrderID", PrdtID.Text);
DataTable dtbl = new DataTable();
da.Fill(dtbl);

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