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POSelect users who did a purchase after a search where some conditions apply in PostgreSQL?
 

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  1. POSelect users who did a purchase after a search where some conditions apply in PostgreSQL?
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    <p>I have this case: users are making searches on the website and some of them purchase. How would you select users over 18 who did a <strong>search</strong> without a following <strong>purchase</strong> where purchase condition is true and search session = purchase session</p> <p>This selects users with search events and age over 18.</p> <pre><code>select DISTINCT ON (id) id, email, users.age, events.type, events.createdon from users LEFT JOIN events ON events.user = users.users where events.type='search' and age&gt;18 and events.condition is true </code></pre> <p>How would I add the condition that they did a <strong>search</strong> event previously in the same session?</p> <p>The table structure for events:</p> <pre><code>----------------------------------------------------- | user | event | date | condition | session | ------------------------------------------------------| | 1 | search | 08-10-2013 | true | A | | 1 | search | 08-10-2013 | true | A | | 2 | search | 08-10-2013 | false | B | | 2 | purchase | 09-10-2013 | false | A | | 2 | search | 09-10-2013 | true | C | | 1 | purchase | 09-10-2013 | true | A | | 3 | search | 09-10-2013 | false | D | | 2 | search | 10-10-2013 | true | H | | 4 | search | 10-10-2013 | false | E | | 4 | search | 10-10-2013 | false | E | | 3 | search | 11-10-2013 | true | D | | 2 | other | 11-10-2013 | true | H | | 1 | search | 11-10-2013 | true | F | | 1 | purchase | 12-10-2013 | true | F | | 3 | purchase | 12-10-2013 | false | D | | 4 | search | 12-10-2013 | true | G | | 2 | other | 12-10-2013 | true | A | ----------------------------------------------------- </code></pre> <p>and the user table is:</p> <pre><code>------------------------ | user | email | age | ------------------------ | 1 | a | 22 | | 2 | b | 34 | | 3 | c | 15 | | 4 | d | 44 | | 5 | e | 39 | ------------------------ </code></pre> <p>The result should be 2 and 4:</p> <pre><code>1 a -&gt; NO because did purchase with condition=true 2 b -&gt; YES because did search, did purchase BUT condition=false 3 c -&gt; NO because did search, did purchase with condition=false BUT age&lt;18 4 d -&gt; YES because did search and no purchase </code></pre> <p>Thank you, I'm just starting with Postgres from Mongo and is much better!</p> <p>UPDATE: corrected result for example</p>
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    1. USAlexandru Rada
    1. USAlexandru Rada
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      1. POSelect users who did a purchase after a search where some conditions apply in PostgreSQL?
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      1. VTUpMod
    2. VO
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      1. VTUpMod
    3. VO
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      1. VTUpMod
    1. CONot related, but: using `distinct on` without an order by is not a good idea.
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      1. USa_horse_with_no_name
    2. COCould you add expected result, please?
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      1. UShedgesky
    3. COYes, the results should be 1 and 3. 2 is not correct because seesion for purchase is different than session from search
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      1. POSelect users who did a purchase after a search where some conditions apply in PostgreSQL?
      1. USAlexandru Rada
 

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