Question

处理我的程序我遇到了一个我无法弄清楚的错误。当我尝试将数据从数据库提取到表中时，就会发生这种情况。我可以从单个表中正确提取它，问题是我必须使用两个表。我很确定这意味着我需要加入。但是，当我尝试加载表格所在的页面时，我在标题中收到错误。

代码：

AccessDataSource theSource = PData;
theSource.SelectCommand = "SELECT Membership.idMembership, Membership.role, Users.lastname" 
        +"FROM Membership "
        +"INNER JOIN Users" 
        +"ON Membership.idUser = Users.idUsers;";
        try
        {
            DataView dv = (DataView)theSource.Select(DataSourceSelectArguments.Empty);

            TableHeaderRow thr = new TableHeaderRow();
            TableHeaderCell ID = new TableHeaderCell();
            TableHeaderCell Role = new TableHeaderCell();
            TableHeaderCell User = new TableHeaderCell();
            ID.Text = "MemberID";
            Role.Text = "Role";
            User.Text = "User";
            thr.Cells.Add(ID);
            thr.Cells.Add(Role);
            thr.Cells.Add(User);
            tblNames.Rows.Add(thr);

            foreach (DataRowView aRow in dv)
            {
                String id = (String)aRow["Membership.idMembership"].ToString();
                String role = (String)aRow["Membership.role"];
                String user = (String)aRow["Users.lastname"].ToString();
                TableRow tr = new TableRow();
                TableCell one = new TableCell();
                TableCell two = new TableCell();
                TableCell three = new TableCell();
                one.Text = id;
                one.HorizontalAlign = HorizontalAlign.Center;
                two.Text = role;
                two.HorizontalAlign = HorizontalAlign.Center;
                three.Text = user;
                three.HorizontalAlign = HorizontalAlign.Center;
                tr.Cells.Add(one);
                tr.Cells.Add(two);
                tr.Cells.Add(three);
                tblNames.Rows.Add(tr);
            }
        }
        catch (Exception ex)
        {
            lblError.Text = ex.ToString();
        }
    }

请告知

Answer 1

本声明：

"SELECT Membership.idMembership, Membership.role, Users.lastname"
+"FROM Membership "
+"INNER JOIN Users" 
+"ON Membership.idUser = Users.idUsers;";

将创建此字符串：

SELECT Membership.idMembership, Membership.role, Users.lastnameFROM Membership INNER JOIN UsersON Membership.idUser = Users.idUsers;

您需要在Users和Users.lastname之后添加空格：

"SELECT Membership.idMembership, Membership.role, Users.lastname "
+"FROM Membership "
+"INNER JOIN Users " 
+"ON Membership.idUser = Users.idUsers;";

Answer 2

您的查询中缺少两个空格：

theSource.SelectCommand = "SELECT Membership.idMembership, Membership.role, Users.lastname "  // added extra space here
    +"FROM Membership "
    +"INNER JOIN Users " // added extra space here
    +"ON Membership.idUser = Users.idUsers;";

Answer 3

在SQL命令中缺少两个空格，一个在SELECT语句的末尾，一个在JOIN语句的末尾，所以请尝试：

theSource.SelectCommand = "SELECT Membership.idMembership, Membership.role, Users.lastname " 
    +"FROM Membership "
    +"INNER JOIN Users " 
    +"ON Membership.idUser = Users.idUsers";

您遇到错误，因为没有空格是无效的SQL查询;你可以在SSMS中查看它。

Answer 4

有些答案缺少空格;在＆＃34; FROM＆＃34;。

之前也需要它们

正确答案是这样的（*表示应该放置额外空格的地方）：

theSource.SelectCommand = "SELECT Membership.idMembership, Membership.role, Users.lastname" 
        + "*FROM Membership "
        + "INNER JOIN Users" 
        + "*ON Membership.idUser = Users.idUsers;"

Join语句的语法错误

4 个答案: