StackOverflow2013

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plurals

PO
primarykey
Id
20084619
data
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0
AnswerCount
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CommentCount
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2013-11-19T23:45:46.853
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2013-11-19T23:58:12.150
LastEditDate
2017-05-23T12:12:41.810
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-1
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20084499
PostTypeId
2
Score
1
ViewCount
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LastEditorDisplayName
text
Body
This is assuming that each user can only be joined once to a conversation: <pre><code>SELECT c.* FROM conversations c JOIN notifications n1 ON n1.conversation_id = c.id JOIN notifications n2 ON n2.conversation_id = c.id WHERE n1.user_id = 1 AND n2.user_id = 2 AND NOT EXISTS ( SELECT 1 FROM notifications n3 WHERE n3.conversation_id = c.id AND n3.user_id <> ALL ('{1,2}') ) </code></pre> This is a special case of relational division. We have assembled a whole arsenal of techniques under this this related question: <a href="https://stackoverflow.com/questions/7364969/how-to-filter-sql-results-in-a-has-many-through-relation">How to filter SQL results in a has-many-through relation</a> The special requirement is to exclude additional matches. I use <code>NOT EXISTS</code> for this end. You could also use <code>LEFT JOIN / IS NULL</code> or <code>NOT IN</code>. More details here: <a href="https://stackoverflow.com/questions/19363481/select-rows-which-are-not-present-in-other-table/19364694#19364694">Select rows which are not present in other table</a> <h3>There could be several notifications for the same user</h3> To avoid duplicate conversations in the result you can use <code>DISTINCT</code> or <code>GROUP BY</code> in addition to the above. Or you suppress duplicates to begin with (probably faster): <pre><code>SELECT c.* FROM conversations c WHERE EXISTS ( SELECT 1 FROM notifications n1 JOIN notifications n2 USING (conversation_id) WHERE n1.conversation_id = c.id AND n1.user_id = 1 AND n2.user_id = 2 ) AND NOT EXISTS ( SELECT 1 FROM notifications n3 WHERE n3.conversation_id = c.id AND n3.user_id <> ALL ('{1,2}') ) </code></pre>
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PostParentId
1. POJoined elements should *all* match some criteria
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1. USErwin Brandstetter
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1. POJoined elements should *all* match some criteria
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1. This table or related slice is empty.
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A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.