指定字段 'ID' 可以引用多个 table

Question

当我尝试通过 ID 查找时，我总是收到此错误：

system.data.oledb.oledbexception the speciefied field 'ID' could refer to more than one table listed in the FROM clause of your SQL Statement

这是我的代码：

public static Invoice GetInvoice(string id)
    {
        OleDbConnection conn = GetConnection();
        Invoice invoice = null;
        if (conn == null)
        {
            return null;
        }
        string sqlString = "SELECT * FROM Person INNER JOIN Employee ON " +
            "Person.ID=Employee.ID WHERE ID = @ID";
        OleDbCommand comm = new OleDbCommand(sqlString, conn);
        comm.Parameters.AddWithValue("@ID", id);
        OleDbDataReader dr = null;
        try
        {
            conn.Open();
            dr = comm.ExecuteReader(CommandBehavior.SingleRow);
            if (dr.Read())
            {
                invoice = new Invoice();
                invoice.PersonID = (string)dr["ID"];
                invoice.FirstName = (string)dr["FirstName"];
                invoice.LastName = (string)dr["LastName"];
                invoice.Age = (int)dr["Age"];
            }
        }
        catch (Exception ex)
        {
            invoice = null;
            MessageBox.Show(ex.ToString());
        }
        finally
        {
            if (conn.State == ConnectionState.Open)
            {
                conn.Close();
            }
        }
        return invoice;
    }

Answer 1

您需要更改查询，目前您选择的是通配符“*”，这意味着它将同时提取人员 ID 和员工 ID，但不会有唯一的引用。更改您的通配符以提取准确的表 ID，如下所示：

SELECT Person.ID, FirstName, LastName FROM...

您还需要将 WHERE 语句更改为：

WHERE Person.ID = @ID

因为 where 语句不知道要过滤哪些表 ID（我知道它们是相同的值，但 SQL 不关心那个）

指定字段 'ID' 可以引用多个 table

The specified field 'ID' could refer to more than one table

c#

oledbconnection