如何使用添加查询添加表中尚不存在的记录

Question

我希望下面的添加查询只添加表中不存在的记录。

INSERT INTO tbl_TRUCK_train_cv ( handling, [text] )
SELECT qryTRUCK_CV_train_CW_2.cv_2 AS handling, "TRUCK: " & [tblTRUCKInformation].[fldTextTXT] & Chr(10) & Chr(13) & "train: " & [tbltrainInformation].[fldTextTXT] AS [text]
FROM (qryTRUCK_CV_train_CW_2 LEFT JOIN tbltrainInformation ON qryTRUCK_CV_train_CW_2.cw = tbltrainInformation.fldID) LEFT JOIN tblTRUCKInformation ON qryTRUCK_CV_train_CW_2.cv = tblTRUCKInformation.fldID
WHERE (((qryTRUCK_CV_train_CW_2.cv)<>""));

例如 表tbl_TRUCK_train_cv中的数据如下：

id | handling   | text
-------------------------
"" | "CV1/CW1"  | "bla"
"" | "CV4/CW7"  | "bla"

add查询中的数据如下：

id | handling   | text
-------------------------
"" | "CV3/CW12" | "bla"
"" | "CV4/CW7"  | "bla"

添加查询应该只添加"" | "CV3/CW12" | "bla"，因为该记录不在表tbl_TRUCK_train_cv中

我不知道如何解决这个问题。 在这种特殊情况下，该表由可能具有重复值的不同查询填充。

Answer 1

好的，这可以在类似于您在问题中制作的插入查询中完成。让我一步一步地引导你：

首先，让我们从连接表和字段“[处理]”的查询开始，它看起来像这样：

    SELECT qryTRUCK_CV_train_CW_2.handling 
    FROM qryTRUCK_CV_train_CW_2 INNER JOIN 
    tbl_TRUCK_train_cv ON qryTRUCK_CV_train_CW_2.handling = tbl_TRUCK_train_cv.handling;

现在，您需要一个查询来查找查询 [qryTRUCK_CV_train_CW_2] 中不在表 [tbl_TRUCK_train_cv] 中的记录。为此，请将 Join 语句更改为 LEFT JOIN。这将显示查询 [qryTRUCK_CV_train_CW_2] 中的所有记录，无论表 [tbl_TRUCK_train_cv] 中是否有匹配记录。

    SELECT qryTRUCK_CV_train_CW_2.handling
    FROM qryTRUCK_CV_train_CW_2 
    LEFT JOIN tbl_TRUCK_train_cv ON qryTRUCK_CV_train_CW_2.handling = 
    tbl_TRUCK_train_cv.handling;

最后，添加条件 WHERE [tbl_TRUCK_train_cv].handling Is Null。

    SELECT qryTRUCK_CV_train_CW_2.handling
    FROM qryTRUCK_CV_train_CW_2 LEFT JOIN tbl_TRUCK_train_cv ON 
    qryTRUCK_CV_train_CW_2.handling = tbl_TRUCK_train_cv.handling
    WHERE (((tbl_TRUCK_train_cv.handling) Is Null));

此 WHERE 子句会将记录限制为仅在 Query 中但不在表中的记录！

你快到了。

接下来，让我们将此作为分组查询，以防查询中的 [处理] 字段中存在重复项。

    SELECT qryTRUCK_CV_train_CW_2.handling
    FROM qryTRUCK_CV_train_CW_2 LEFT JOIN tbl_TRUCK_train_cv ON 
    qryTRUCK_CV_train_CW_2.handling = tbl_TRUCK_train_cv.handling
    WHERE (((tbl_TRUCK_train_cv.handling) Is Null))
    GROUP BY qryTRUCK_CV_train_CW_2.handling;

最后，将这些结果插入到表中 [tbl_TRUCK_train_cv]

    INSERT INTO tbl_TRUCK_train_cv ( handling )
    SELECT qryTRUCK_CV_train_CW_2.handling
    FROM qryTRUCK_CV_train_CW_2 LEFT JOIN tbl_TRUCK_train_cv ON 
    qryTRUCK_CV_train_CW_2.handling = tbl_TRUCK_train_cv.handling
    WHERE (((tbl_TRUCK_train_cv.handling) Is Null))
    GROUP BY qryTRUCK_CV_train_CW_2.handling;