MySql通過其他元素從兩個不同的表中選擇ID，然後ids

我有兩個表tableA和tableB，它們都有字段id, code, validFrom和validUntil。我試圖從tableA.code = tableB.code,tableA.validFrom = tableB.validFrom和tableB.validUntil = Null && tableA.validUntil != Null這兩個表中獲得ID。我試了一個選擇與內部聯接MySql通過其他元素從兩個不同的表中選擇ID，然後ids

Select a.id, b.id from tableA as a 
inner join tableB as b ON 
    (a.code = b.code and a.validFrom = b.validFrom) 
where b.validUntil is Null and a.validFrom != Null

但我得到0結果與此。表例如

TableA 
id | code | validFrom | validUntil | Extra 
--------------------------------------------- 
1 | ABCD | 2010-01-01 | 2016-01-01 | NULL 
2 | EFA | 2010-01-01 | 2015-01-01 | 12 
3 | FAS | 2012-01-01 | 2017-01-01 | 13

而且

TableB 
id | code | validFrom | validUntil | Extra 
--------------------------------------------- 
1 | EFA | 2010-01-01 | NULL  | 12 
2 | ABCD | 2010-01-01 | NULL  | NULL 
3 | FAS | 2012-01-01 | 2017-01-01 | 13

所以結果應該是

TableA.id | TableB.id 
--------------------- 
    1 | 2 
    2 | 1

編輯：

Select a.id, b.id from tableA as a 
left join tableB as b ON 
    a.code = b.code 
    and a.validFrom = b.validFrom 
    and a.Extra = b.Extra 
where b.validUntil is Null 
and a.validFrom is not Null

來源

2017-04-10 Lukas Karmanovas

使用IS NOT NULL，而不是!= null。您不要在數據庫中使用與NULL值相等的運算符。更改以下條件

and a.validFrom != Null

對此

and a.validFrom is not Null

同樣，使用LEFT JOIN，而不是像

Select a.id, b.id from tableA as a 
left join tableB as b ON 
    a.code = b.code 
    and a.validFrom = b.validFrom 
where b.validUntil is Null 
and a.validFrom is not Null

來源

2017-04-10 14:58:41 Rahul

是啊，我的壞忘了寫在這裏像那個用於Java –

@LukasKarmanovas，請參閱編輯答案，如果有幫助。 – Rahul

是的，這是工作，但即時通訊沒有得到所有的ID，即時獲取其中一些 –

呀什麼我想要做的是類似於@Rahul說

Select a.id, b.id from tableA as a 
left join tableB as b ON 
    a.code = b.code 
    and a.validFrom = b.validFrom 
where b.validUntil is Null 
and a.validFrom is not Null 
and (a.Extra = b.Extra or (a.Extra is NULL and b.Extra is NULL))

來源

2017-04-10 15:54:15

MySql通過其他元素從兩個不同的表中選擇ID，然後ids

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