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Re: select items based on 2 columns

Carl Sopchak <carl@sopchak.me>

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From: Carl Sopchak <carl@sopchak.me>
To: pgsql-sql@lists.postgresql.org
Date: 2022-08-08T16:30:50Z
Lists: pgsql-sql

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    <p>You can also quote column names that are SQL keywords, so "in"
      and "out" would also work, but I also agree that it's not great
      practice.  However, IMHO, IN and OUT doesn't tell you a lot.  In
      and out of what?  Inbound/outbound?  In_water / out_of_water?  You
      get the idea.  Using clear column names helps prevent misuse
      (intentional or not).<br>
    </p>
    <div class="moz-cite-prefix">On 8/8/22 12:17, Pierre Chevalier
      wrote:<br>
    </div>
    <blockquote type="cite"
      cite="mid:d74da674-0902-026e-8a63-a2b24086c9af@free.fr">
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        <pre>Hello,

Short answer:
SELECT id FROM tbl WHERE in and out;


BUT this will never work as is.


Longer answer:
First of all, it would be better not to name fields with word having a meaning in SQL: "in" is not accepted as a valid field name.
&gt;From now on, to get rid of this problem, I renamed the in and out fields by appending an "x" at the end: "in" becomes "inx" and "out" becomes "outx".

Here is the complete answer; I added some data matching your criteria:

-- Create the table:
CREATE TEMPORARY TABLE tbl (id integer, id_b integer, inx boolean, outx boolean);

-- Put some data into it:
INSERT INTO tbl (id, id_b, inx, outx) VALUES
(51, 57, false, false),
(51, 42,  true, false),
(51, 32, false, false),
(51, 76, false, true),
(51, 49,  true, false),
(51, 47,  true, true);

-- Select id where inx is true and outx is true:
SELECT id FROM tbl WHERE inx and outx;

-- Output:
┌────┐
│ id │
├────┤
│ 51 │
└────┘</pre>
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      <div class="moz-cite-prefix"> </div>
      <div class="moz-cite-prefix">
        <pre>À+
Pierre
</pre>
      </div>
      <div class="moz-cite-prefix"><br>
      </div>
      <div class="moz-cite-prefix">Le 08/08/2022 à 10:24, Shaozhong SHI
        a écrit :<br>
      </div>
      <blockquote type="cite"
cite="mid:CA+i5JwYCPBDcenq_godJqtjApLyOeJHxo-Joova3wrAYtM6QOA@mail.gmail.com">
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        <div dir="ltr">The following is the type of data:
          <div><br>
          </div>
          <div>id  id_b   in    out</div>
          <div>51 57     false false</div>
          <div>51 42     true   false</div>
          <div>51   32   false  false</div>
          <div>51   76   false  true</div>
          <div>51  49     true   false</div>
          <div><br>
          </div>
          <div><br>
          </div>
          <div>How to do the following:</div>
          <div><br>
          </div>
          <div>select id from tbl   if in is true and out is true are
            found?</div>
          <div><br>
          </div>
          <div>Regards,</div>
          <div><br>
          </div>
          <div>David</div>
        </div>
      </blockquote>
      <p><br>
      </p>
      <pre class="moz-signature" cols="72">-- 
Pierre Chevalier
</pre>
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