Sent: Monday, November 20, 2017 3:55:42 PM
To: sqlite-users@mailinglists.sqlite.org
Subject: Re: [sqlite] Help with left joins
On 2017/11/20 5:33 PM, x wrote:
>> Only if ColB, ColC and ColD are unique in their tables. Otherwise each join
>> has the potential of returning multiple row
On 2017/11/20 5:33 PM, x wrote:
Only if ColB, ColC and ColD are unique in their tables. Otherwise each join has
the potential of returning multiple rows, which will carry over to the next
joins.
Thanks David, I did say ColB, ColC & ColD were primary keys.
Any kind of Query (especially of
>Only if ColB, ColC and ColD are unique in their tables. Otherwise each join
>has the potential of returning multiple rows, which will carry over to the
>next joins.
Thanks David, I did say ColB, ColC & ColD were primary keys.
___
sqlite-users mailing
, November 20, 2017 8:22 AM
To: SQLite mailing list
Subject: Re: [sqlite] Help with left joins
I’m not sure what you’re saying Simon or maybe you’re not sure what I’m asking.
I’m not complaining about the fact SQLite fails to drop what I think is a
redundant table in the second explain, I’m merely
?
From: sqlite-users <sqlite-users-boun...@mailinglists.sqlite.org> on behalf of
Simon Slavin <slav...@bigfraud.org>
Sent: Monday, November 20, 2017 12:34:29 PM
To: SQLite mailing list
Subject: Re: [sqlite] Help with left joins
On 20 Nov 2017, at 11:09a
On 20 Nov 2017, at 11:09am, x wrote:
> explain
> select ColA from TblA
> left join TblB using (ColB)
> left join TblC using (ColC)
> left join TblD using (ColD)
> where ColBX=?;
>
> there will be no trace of TblC or TblD as they're redundant.
Although you have not
Suppose
TblB has primary key ColB and contains a column ColBX
TblC has primary key ColC and contains a column ColCX
TblD has primary key ColD and contains a column ColDX
TblA has primary key ColA and also contains columns ColB, ColC and ColD
(i.e. TblB, TblC and TblD are effectively lookup
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