StackOverflow2013

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plurals

PO
primarykey
Id
1228476
data
AcceptedAnswerId
0
AnswerCount
0
ClosedDate
CommentCount
0
CommunityOwnedDate
CreationDate
2009-08-04T16:18:03.633
FavoriteCount
0
LastActivityDate
2009-08-04T16:26:52.617
LastEditDate
2009-08-04T16:26:52.617
LastEditorUserId
55159
OwnerUserId
55159
ParentId
1228338
PostTypeId
2
Score
7
ViewCount
0
LastEditorDisplayName
text
Body
Seems you want a French description if it exists, otherwise fallback to English. <pre><code>SELECT item.id, COALESCE( ( SELECT lang.data FROM language l WHERE l.item = i.id AND l.language = 'fr' ), ( SELECT lang.data FROM language l WHERE l.item = i.id AND l.language = 'en' ) ) AS description FROM item i </code></pre> , or this: <pre><code>SELECT item.id, COALESCE(lfr.data, len.data) FROM item i LEFT JOIN language lfr ON lfr.item = i.id AND lfr.language = 'fr' LEFT JOIN language len ON len.item = i.id AND len.language = 'en' </code></pre> The first query is more efficient if the probability of finding French description is high (it will not evaluate the second subquery if the first one succeeds). In <code>SQL Server</code>, <code>Oracle</code> and <code>PostgreSQL</code> this one will probably more efficient if you have lots of French descriptions: <pre><code>SELECT item.id, COALESCE( lfr.data, ( SELECT lang.data FROM language l WHERE l.item = i.id AND l.language = 'en' ) ) AS description FROM item i LEFT JOIN language lfr ON lfr.item = i.id AND lfr.language = 'fr' </code></pre> This query will use an efficient method (<code>HASH JOIN</code> or <code>MERGE JOIN</code>) to join the French descriptions, and will fallback to English one only if necessary. For <code>MySQL</code>, the <code>1st</code> and the <code>3rd</code> queries make no difference. In all systems, create a composite index on <code>language (item, language)</code>
Tags
Title
singulars
PostAcceptedAnswerId
1. This table or related slice is empty.
PostParentId
1. POLEFT JOIN using OR
 singulars
 PostTypePostTypeId
 PTQuestion
PostTypePostTypeId
1. PTAnswer
UserLastEditorUserId
1. USQuassnoi
UserOwnerUserId
1. USQuassnoi
plurals
PostLinksPostIdRelatedPostId
1. This table or related slice is empty.
PostLinksRelatedPostIdPostId
1. This table or related slice is empty.
PostsAcceptedAnswerId
1. POLEFT JOIN using OR
 singulars
 PostTypePostTypeId
 PTQuestion
PostsParentIdCreationDate
1. This table or related slice is empty.
VotesPostIdCreationDate
1. VO
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 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTAcceptedByOriginator
2. VO
 singulars
 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
3. VO
 singulars
 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
CommentsPostId
1. This table or related slice is empty.

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