案例陳述，而不是多個選擇

我有幾個代碼聲明如下，我想找出一種方法，使這更簡單和更容易。我會假設CASE聲明是最好的，但經過幾天的試驗和錯誤之後，我一直無法弄清楚如何去做。任何和所有的幫助和/或解釋將不勝感激。案例陳述，而不是多個選擇

select Count(lcs.statename) as [Name 1] 
    FROM hsi.itemlc as ilc 
    LEFT JOIN hsi.lcstate as lcs on lcs.statenum = ilc.statenum 
    where lcs.statename = 'Follow Up' 
    AND lcnum = '412' 
    AND status = '0' 
select Count(lcs.statename) as [Name 2] 
    FROM hsi.itemlc as ilc 
    LEFT JOIN hsi.lcstate as lcs on lcs.statenum = ilc.statenum 
    where lcs.statename = 'Initial Review' 
    AND lcnum = '412' 
    AND status = '0' 
select Count(lcs.statename) as [Name 3] 
    FROM hsi.itemlc as ilc 
    LEFT JOIN hsi.lcstate as lcs on lcs.statenum = ilc.statenum 
    where lcs.statename = 'Execution' 
    AND lcnum = '412' 
    AND status = '0' 
select Count(lcs.statename) as [Name 4] 
    FROM hsi.itemlc as ilc 
    LEFT JOIN hsi.lcstate as lcs on lcs.statenum = ilc.statenum 
    where lcs.statename = 'Holdback' 
    AND lcnum = '412' 
    AND status = '0'

來源

2012-10-16 John

*** SQL ***只是*結構化查詢語言* - 許多數據庫系統使用的語言，但不是數據庫產品......語法細節是供應商特定的 - 所以我們真的需要知道什麼**數據庫系統**（和哪個版本），你正在使用...... –

嘗試類似：

SELECT SUM(CASE WHEN lcs.statename = 'Follow Up' THEN 1 ELSE 0 END) as [Name 1], 
    SUM(CASE WHEN lcs.statename = 'Initial Review' THEN 1 ELSE 0 END) as [Name 2], 
    SUM(CASE WHEN lcs.statename = 'Execution' THEN 1 ELSE 0 END) as [Name 3], 
    SUM(CASE WHEN lcs.statename = 'Holdback' THEN 1 ELSE 0 END) as [Name 4] 
FROM hsi.itemlc as ilc 
LEFT JOIN hsi.lcstate as lcs on lcs.statenum = ilc.statenum 
WHERE lcnum = '412' 
AND status = '0'

來源

2012-10-16 16:46:16

這工作完美...幾天下來，但感謝一百萬 – John

現在，如果我要添加其他列......我收到了「消息8120，級別16，狀態1，行1 列'hsi.itemlc.itemnum'在選擇列表中無效，因爲它不包含在聚合函數或GROUP BY子句中。」試圖在SELECT後添加 ilc.itemnum as [test]時出錯 – John

@John您必須將GROUP BY添加到該列中。 –

您可以用SUM（做）和CASE：

SELECT 
     SUM(CASE WHEN lcs.statename = 'Follow Up' THEN 1 ELSE 0 END) as [Name 1], 
     SUM(CASE WHEN lcs.statename = 'Initial Review' THEN 1 ELSE 0 END) as [Name 2], 
     ... 
    FROM hsi.itemlc as ilc 
    LEFT JOIN hsi.lcstate as lcs on lcs.statenum = ilc.statenum 
    WHERE lcnum = '412' AND status = '0';

或者，如果你能讀多行，你可以使用GROUP BY：

SELECT lcs.statename, COUNT(*) AS num 
    FROM hsi.itemlc as ilc 
    LEFT JOIN hsi.lcstate as lcs on lcs.statenum = ilc.statenum 
    WHERE lcnum = '412' AND status = '0' 
    GROUP BY lcs.statename;

哪會給喲ü像

Follow Up  25 
Initial Review 17 
...

來源

2012-10-16 16:46:41 LSerni

可以使用CASE語句與SUM()功能，如下所示：

SELECT SUM(CASE WHEN lcs.statename = 'Follow Up' THEN 1 ELSE 0 END) as [Name 1], 
     SUM(CASE WHEN lcs.statename = 'Initial Review' THEN 1 ELSE 0 END) as [Name 2], 
     SUM(CASE WHEN lcs.statename = 'Execution' THEN 1 ELSE 0 END) as [Name 3], 
     SUM(CASE WHEN lcs.statename = 'Holdback' THEN 1 ELSE 0 END) as [Name 4] 
FROM hsi.itemlc as ilc 
LEFT JOIN hsi.lcstate as lcs on lcs.statenum = ilc.statenum 
WHERE lcnum = '412' 
    AND status = '0'

這導致每個州的名字條件計數。

來源

2012-10-16 16:47:20

案例陳述，而不是多個選擇

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