對不起,標題不好。我不確定如何描述我的問題。我寫了一個查詢返回約23,000條記錄。很多這些記錄都有類似的信息,我只想選擇最大字段爲dbo.tblMsgsOnAir_Type8.fldBuddyLinkSigStrength
的記錄。我嘗試了所有其他列被選中的分組,但它似乎不能正常工作。我不完全理解SQL,特別是最大和組函數。當我只想或需要選擇一件事情時,我可以做簡單的最大功能。我不明白它是如何工作的,當我想選擇一堆其他數據。以下是查詢。選擇最大與其他項目
SELECT
dbo.tblmeterinfo.fldMeterSerialNumber AS "MOP_FNP_Meter",
dbo.tblMsgsOnAir_Type8.fldRBuddyId AS "MOP_FNP_FNID",
dbo.TBLMETERMAINT.fldmeterid AS "Meter_ID_Helped",
dbo.tblMsgsOnAir_Type8.fldCBuddyId AS "FNID_Helped",
dbo.fn_dt(dbo.tblMsgsOnAir_Type8.fldRBuddyToi) AS "TOI",
dbo.tblMsgsOnAir_Type8.fldBuddyLinkSigStrength AS "Sig_Str",
dbo.TBLSAWN_CIS_INFO.SML AS "Buddy_SML",
dbo.TBLMETERLIST.fldaddress AS "Buddy_Address",
dbo.TBLSAWNGISCOORD.X_COORD AS "X_Coord",
dbo.TBLSAWNGISCOORD.Y_COORD AS "Y_Coord"
FROM dbo.tblMsgsOnAir_Type8
LEFT OUTER JOIN dbo.TBLMETERLIST
ON (dbo.TBLMETERLIST.FLDREPID = dbo.tblMsgsOnAir_Type8.fldCBuddyId)
LEFT OUTER JOIN dbo.TBLMETERMAINT
ON (dbo.TBLMETERMAINT.FLDREPID = dbo.tblMsgsOnAir_Type8.fldCBuddyID)
LEFT OUTER JOIN dbo.TBLSAWN_CIS_INFO
ON (dbo.TBLSAWN_CIS_INFO.FLDREPID = dbo.tblMsgsOnAir_Type8.fldCBuddyId)
LEFT OUTER JOIN dbo.TBLSAWNGISCOORD
ON (dbo.TBLSAWNGISCOORD.SRV_MAP_LOC = dbo.TBLSAWN_CIS_INFO.SML)
LEFT OUTER JOIN dbo.tblmeterinfo
ON (dbo.tblmeterinfo.fldRepId = dbo.tblMsgsOnAir_Type8.fldRBuddyId)
WHERE dbo.tblMsgsOnAir_Type8.fldRBuddyId IN (SELECT
dbo.tblSAWN_FNPmap.Repid
FROM dbo.tblSAWN_FNPmap)
AND dbo.TBLMETERMAINT.fldmeterid IS NOT NULL
下面的查詢很簡單,做我想要的,但沒有得到所有其他字段。該查詢只返回617條記錄。我希望上述查詢返回617條記錄,但包含我選擇的所有其他信息。
SELECT
dbo.TBLMETERMAINT.fldmeterid AS "Meter_ID_Helped",
MAX(dbo.tblMsgsOnAir_Type8.fldBuddyLinkSigStrength) AS "Max_Sig"
FROM dbo.tblMsgsOnAir_Type8
LEFT OUTER JOIN dbo.TBLMETERMAINT
ON (dbo.TBLMETERMAINT.FLDREPID = dbo.tblMsgsOnAir_Type8.fldCBuddyID)
WHERE dbo.tblMsgsOnAir_Type8.fldRBuddyId IN (SELECT
dbo.tblSAWN_FNPmap.Repid
FROM dbo.tblSAWN_FNPmap)
AND dbo.TBLMETERMAINT.fldmeterid IS NOT NULL
GROUP BY dbo.TBLMETERMAINT.fldmeterid
感謝您的建議。我會嘗試修改查詢星期一併回報。我認爲這是有道理的。 – AdamH