如何获取两个SQL查询并将它们组合成一个查询

Posted

tags:

篇首语:本文由小常识网(cha138.com)小编为大家整理,主要介绍了如何获取两个SQL查询并将它们组合成一个查询相关的知识,希望对你有一定的参考价值。

我正在为我的程序的自定义脚本取得进展:

// You might want to use a date range and specify the first Sunday and use that variable.
// Or, you may want to have a user request variable where they key in the starting Sunday #YYYY MM DD#

// Let us work out the current week number
$iStartWeekNumber = $Today#CUSTOMDATE[%W] + 1
TEXT "Current week number (1 to 52): $iStartWeekNumber"
EOL

// Let us work out the current year
$iThisYear = $Today#CUSTOMDATE[%Y]
TEXT "Current year: $iThisYear"
EOL

// Now we can do a manual for loop from iStartWeekNumber to the end of the year
TEXT "TODO: Work out how to show the date nicely formatted"
EOL
$datWeek = $Today
LOOP AS $iWeekNumber FROM $iStartWeekNumber TO 52
    $datWeek = $datWeek + 7
    TEXT "Week: $iWeekNumber"
    EOL
    TEXT "Date: {$datWeek#SHORTDATE}"
    EOL

    // Iterate all available speakers
    LOOP FROM "Congregation Speakers" NODATERANGE WHERE "Congregation" IS "$LocalCong" AND "notavail" IS "0"  SORTBY "Speaker"

        // Requirement 1
        // 1. He is not in program for a talk in our home or another congregation for that same WEEKEND (either saturday or sunday)

        // Store the current speaker into a variable
        VARIABLE_FIELD "Speaker" "$strCurrentSpeaker"

        LOOP SQL "SELECT * FROM [Home Talks] WHERE ((DatePart('ww',[Last Given],2)=$iWeekNumber)) AND ((DatePart('yyyy',[Last Given])=$iThisYear)) AND [Speaker] = '$strCurrentSpeaker' AND [Congregation]='$LocalCong'" ROW_COUNT "$iNumHomeTalks"
        END_LOOP

        LOOP SQL "SELECT * FROM [Away Talks] WHERE ((DatePart('ww',[Talk Date],2)=$iWeekNumber)) AND ((DatePart('yyyy',[Talk Date])=$iThisYear)) AND [Brother] = '$strCurrentSpeaker'" ROW_COUNT "$iNumAwayTalks"
        END_LOOP

        IF "$iNumHomeTalks" IS "0" AND "$iNumAwayTalks" IS "0"
            // Requirement 2
            // 2. He should not give a talk more than once in a MONTH (so he is unavailable if he will be giving a talk during the month)
            $iMonth = date_part($datWeek,"M")
            LOOP SQL "SELECT * FROM [Home Talks] WHERE ((DatePart('m',[Last Given])=$iMonth)) AND ((DatePart('yyyy',[Last Given])=$iThisYear)) AND [Speaker] = '$strCurrentSpeaker' AND [Congregation]='$LocalCong'" ROW_COUNT "$iNumHomeTalksForMonth"
            END_LOOP
            LOOP SQL "SELECT * FROM [Away Talks] WHERE ((DatePart('m',[Talk Date])=$iMonth)) AND ((DatePart('yyyy',[Talk Date])=$iThisYear)) AND [Brother] = '$strCurrentSpeaker'" ROW_COUNT "$iNumAwayTalksForMonth"
            END_LOOP
            $iTotalTalksForMonth = $iNumHomeTalksForMonth + $iNumAwayTalksForMonth
            IF "$iTotalTalksForMonth" IS "0"
                // Requirement 3
                // 3. That same weekend either one or more than x speakers are not out for a talk or unavailable

                // TO DO
                TEXT "$strCurrentSpeaker"
                EOL
            END_IF
        END_IF
    END_LOOP

    BLANK *1
END_LOOP

我想特别关注两组SQL查询:

第1组:

LOOP SQL "SELECT * FROM [Home Talks] WHERE ((DatePart('ww',[Last Given],2)=$iWeekNumber)) AND ((DatePart('yyyy',[Last Given])=$iThisYear)) AND [Speaker] = '$strCurrentSpeaker' AND [Congregation]='$LocalCong'" ROW_COUNT "$iNumHomeTalks"
END_LOOP
LOOP SQL "SELECT * FROM [Away Talks] WHERE ((DatePart('ww',[Talk Date],2)=$iWeekNumber)) AND ((DatePart('yyyy',[Talk Date])=$iThisYear)) AND [Brother] = '$strCurrentSpeaker'" ROW_COUNT "$iNumAwayTalks"
END_LOOP

并设置2:

LOOP SQL "SELECT * FROM [Home Talks] WHERE ((DatePart('m',[Last Given])=$iMonth)) AND ((DatePart('yyyy',[Last Given])=$iThisYear)) AND [Speaker] = '$strCurrentSpeaker' AND [Congregation]='$LocalCong'" ROW_COUNT "$iNumHomeTalksForMonth"
END_LOOP
LOOP SQL "SELECT * FROM [Away Talks] WHERE ((DatePart('m',[Talk Date])=$iMonth)) AND ((DatePart('yyyy',[Talk Date])=$iThisYear)) AND [Brother] = '$strCurrentSpeaker'" ROW_COUNT "$iNumAwayTalksForMonth"
END_LOOP

以上是我自己的脚本语言。但在引擎盖下它采用原始SQL查询并使用Jet在Microsoft Access数据库上运行它。

他们工作正常。但我想知道这两组查询是否可以合并为一组?如您所见,我想要建立的只是找到的记录数。因此,如果我可以组合[Home Talks][Away Talks]的查询,我最终只会执行2个查询而不是4个。

在我看来,我需要使用UNION,但每个表中的一个字段是不同的:

  • Last Given
  • Talk Date

所以我不能在两个查询之间拼接关键字UNION

答案

您可以通过别名字段名称来使用UNION

SELECT [Last Given] AS MyFieldName FROM [Home Talks]
UNION
SELECT [Talk Date] AS MyFieldName FROM [Away Talks]

您只需列出单个字段而不是*,并确保任何输出字段匹配类型(或转换为字符串作为查询的一部分)和名称(别名)。

编辑:如果两个字段完全不相关(与具有不同字段名称的相同或类似信息相反),则这是一个附加选项:

SELECT [Last Given], NULL AS [Talk Date] FROM [Home Talks]
UNION
SELECT NULL AS [Last Given], [Talk Date] FROM [Away Talks]

以上是关于如何获取两个SQL查询并将它们组合成一个查询的主要内容,如果未能解决你的问题,请参考以下文章

如何组合两个查询并将数据放入一行?

如何将这两个 SQL 查询组合成一个查询?

如何将 4 个 sql 查询组合成一个性能良好的查询?

如何将这两个查询组合成一个查询?

将多个查询组合成一个查询

如何获取多个Sample()矢量输出并将它们组合成一个数据帧