如果連接表中沒有記錄，則爲mysql結果

我查看了搜索結果，但找不到答案。如果在houses_availability中沒有匹配的記錄，我需要查看houses_houses中的記錄。我知道它與IS NULL有關，但所有我tryed失敗。請幫忙。如果連接表中沒有記錄，則爲mysql結果

SELECT 
    houses_houses.*, 
    houses_availability.from_date 
FROM 
    houses_houses 
LEFT JOIN 
    houses_availability ON houses_houses.sid=houses_availability.housesid 
WHERE 
    houses_availability.from_date>='2015-09-05' 
AND 
    houses_availability.until_date<'2015-09-11' 
ORDER BY houses_houses.sid LIMIT 0, 9

來源

2015-09-02 user2369818

小點，你是選擇houses_availability.from_date，但你似乎想只包含沒有houses_availability行的行。因此，對於任何返回的行，該字段總是爲NULL。 – Kickstart

您檢查在LEFT OUTER NULL加入提交的WHERE子句中： -

SELECT 
    houses_houses.*, 
    houses_availability.from_date 
FROM houses_houses 
LEFT JOIN houses_availability 
ON houses_houses.sid=houses_availability.housesid 
AND houses_availability.from_date>='2015-09-05' 
AND houses_availability.until_date<'2015-09-11' 
WHERE houses_availability.housesid IS NULL 
ORDER BY houses_houses.sid LIMIT 0, 9

需要注意的是，你不應該檢查任一列從LEFT OUTER在連接表WHERE子句，因爲這會排除連接後的整個行，而不是在連接之前排除LEFT OUTER JOINed表的行。因此，檢查日期範圍ON子句

來源

2015-09-02 09:02:45 Kickstart

非常感謝Kickstart。 – user2369818

您需要包括你houses_availability標準中加入.. ON子句：

SELECT houses_houses.*, houses_availability.from_date 
FROM houses_houses 
LEFT JOIN houses_availability ON (houses_houses.sid=houses_availability.housesid AND houses_availability.from_date>='2015-09-05' 
    AND houses_availability.until_date<'2015-09-11') 
WHERE 
    houses_availability.housesid is null 
ORDER BY houses_houses.sid LIMIT 0, 9

來源

2015-09-02 09:03:00 vhu

如果連接表中沒有記錄，則爲mysql結果

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