Question

我不是SQL的专家，并且已经识别出我的一些现有经典asp代码中的错误，因此它在所有情况下都不起作用。我希望有一些优秀的SQL经验的人可以帮助我编写两种情况发生时更复杂的情况

If intItemType = SV_ITEM_TYPE_MATRIX然后使用SQL的这部分

LEFT OUTER JOIN usd_matrixSets MS " &_
    "ON MS.itemID = SI.itemID " &_

但是当intItemType <> SV_ITEM_TYPE_MATRIX时，它会被忽略。

正如你所看到的，我已经为这两种情况编写了代码，但这实际上并没有涵盖我可能发生的情况。

以下是代码：

If intItemType = SV_ITEM_TYPE_MATRIX Then   
    strSQL = "SELECT SI.itemID, itemType, itemText, minimumValue, maximumValue, dataType, MS.matrixSetType, MS.matrixSetID " &_
             "FROM usd_SurveyItem SI " &_
             "LEFT OUTER JOIN usd_matrixSets MS " &_
             "ON MS.itemID = SI.itemID " &_
             "WHERE surveyID = " & intSurveyID &_
             " AND itemType " &_
             "In(" & SV_ITEM_TYPE_TEXTAREA & "," &_
                    SV_ITEM_TYPE_SINGLE_LINE & "," &_
                    SV_ITEM_TYPE_DATE & "," &_
                    SV_ITEM_TYPE_CHECKBOXES & "," &_
                    SV_ITEM_TYPE_RADIO & "," &_
                    SV_ITEM_TYPE_DROPDOWN & "," &_
                    SV_ITEM_TYPE_MATRIX & "," &_
                    SV_ITEM_TYPE_UPLOAD_FILE & ")" &_
             " AND pageID = " & intPageNumber &_
             " ORDER BY pageID, SI.orderByID "

        else            
    strSQL = "SELECT SI.itemID, itemType, itemText, minimumValue, maximumValue, dataType" &_
             " FROM usd_SurveyItem SI " &_
             "WHERE surveyID = " & intSurveyID &_
             " AND itemType " &_
             "In(" & SV_ITEM_TYPE_TEXTAREA & "," &_
                    SV_ITEM_TYPE_SINGLE_LINE & "," &_
                    SV_ITEM_TYPE_DATE & "," &_
                    SV_ITEM_TYPE_CHECKBOXES & "," &_
                    SV_ITEM_TYPE_RADIO & "," &_
                    SV_ITEM_TYPE_DROPDOWN & "," &_
                    SV_ITEM_TYPE_MATRIX & "," &_
                    SV_ITEM_TYPE_UPLOAD_FILE & ")" &_
             " AND pageID = " & intPageNumber &_
             " ORDER BY pageID, SI.orderByID "      

        end if

我的问题是，有时我在我的数据库中同时拥有SV_ITEM_TYPE_MATRIX和其他所有内容。我该如何重写这段代码？

Answer 1

您应该始终执行LEFT JOIN，并且当MS.matrixSetType不是MS.matrixSetID时，只允许其他值（NULL和SV_ITEM_TYPE_MATRIX）为SELECT SI.itemID, itemType, itemText, minimumValue, maximumValue, dataType, MS.matrixSetType, MS.matrixSetID FROM usd_SurveyItem SI LEFT OUTER JOIN usd_matrixSets MS ON MS.itemID = SI.itemID AND @intItemType = SI.itemType WHERE surveyID = @intSurveyID AND itemType IN ( ... ) AND pageID = @intPageNumber ORDER BY pageID, SI.orderByID。

类似的东西（我将使用参数来避免SQL注入漏洞）：

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SQL经典的asp - 条件语句

1 个答案: