From: Nikolaus Thiel <klt@fsfe.org>
Subject: Bad return type in example
Reply-To: klt@fsfe.org
To: pgsql-docs@postgresql.org
Organization: Free Software Foundation Europe
Message-ID: <f37673c3-8786-b493-e244-93b7dc28028e@fsfe.org>
Date: Wed, 8 Mar 2017 10:00:27 +0100
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From: Nikolaus Thiel <klt@fsfe.org>
Reply-To: klt@fsfe.org
To: pgsql-docs@postgresql.org
Message-ID: <f37673c3-8786-b493-e244-93b7dc28028e@fsfe.org>
Subject: Bad return type in example

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  * postgresql-9.6-A4.pdf, page 891
  * https://www.postgresql.org/docs/9.6/static/xfunc-sql.html#XFUNC-SQL-B=
ASE-FUNCTIONS

Dear Doc Writers,

Would it not be better to change the return type of the following two sam=
ple functions to numeric ?


CREATE FUNCTION tf1 (accountno integer, debit numeric) RETURNS integer AS=
 $$
    UPDATE bank
        SET balance =3D balance - debit
        WHERE accountno =3D tf1.accountno;
    SELECT balance FROM bank WHERE accountno =3D tf1.accountno;
$$ LANGUAGE SQL;


CREATE FUNCTION tf1 (accountno integer, debit numeric) RETURNS integer AS=
 $$
    UPDATE bank
        SET balance =3D balance - debit
        WHERE accountno =3D tf1.accountno
    RETURNING balance;
$$ LANGUAGE SQL;


Since debit is of type numeric, balance is (probably) numeric too, so the=
 function ought to return numeric. I guess that the function works as it =
is using implicit type cast.

With best regards,
Nikolaus Thiel


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<html>
  <head>
    <meta http-equiv=3D"content-type" content=3D"text/html; charset=3Dutf=
-8">
  </head>
  <body bgcolor=3D"#FFFFFF" text=3D"#000000">
    <ul>
      <li> postgresql-9.6-A4.pdf, page 891<br>
      </li>
      <li><a
href=3D"https://www.postgresql.org/docs/9.6/static/xfunc-sql.html#XFUNC-S=
QL-BASE-FUNCTIONS">https://www.postgresql.org/docs/9.6/static/xfunc-sql.h=
tml#XFUNC-SQL-BASE-FUNCTIONS</a><br>
      </li>
    </ul>
    <p>Dear Doc Writers,</p>
    <p>Would it not be better to change the return type of the following
      two sample functions to <font color=3D"#3333ff">numeric</font> ?</p=
>
    <p>
      <meta http-equiv=3D"content-type" content=3D"text/html; charset=3Du=
tf-8">
    </p>
    <p><tt><br>
      </tt></p>
    <p><tt>CREATE FUNCTION tf1 (accountno integer, debit numeric)
        RETURNS <font color=3D"#3333ff">integer</font> AS $$</tt><tt><br>=

      </tt><tt>=C2=A0=C2=A0=C2=A0 UPDATE bank</tt><tt><br>
      </tt><tt>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 SET balance =3D=
 balance - debit</tt><tt><br>
      </tt><tt>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 WHERE accountno=
 =3D tf1.accountno;</tt><tt><br>
      </tt><tt>=C2=A0=C2=A0=C2=A0 SELECT balance FROM bank WHERE accountn=
o =3D
        tf1.accountno;</tt><tt><br>
      </tt><tt>$$ LANGUAGE SQL;</tt><tt><br>
      </tt></p>
    <p>
      <meta http-equiv=3D"content-type" content=3D"text/html; charset=3Du=
tf-8">
    </p>
    <p><tt><br>
      </tt></p>
    <p><tt>CREATE FUNCTION tf1 (accountno integer, debit numeric)
        RETURNS <font color=3D"#3333ff">integer</font> AS $$</tt><tt><br>=

      </tt><tt>=C2=A0=C2=A0=C2=A0 UPDATE bank</tt><tt><br>
      </tt><tt>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 SET balance =3D=
 balance - debit</tt><tt><br>
      </tt><tt>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 WHERE accountno=
 =3D tf1.accountno</tt><tt><br>
      </tt><tt>=C2=A0=C2=A0=C2=A0 RETURNING balance;</tt><tt><br>
      </tt><tt>$$ LANGUAGE SQL;</tt></p>
    <p><tt><br>
      </tt></p>
    <p>Since debit is of type numeric, balance is (probably) numeric
      too, so the function ought to return numeric. I guess that the
      function works as it is using implicit type cast.</p>
    <p>With best regards,<br>
      Nikolaus Thiel</p>
    <p><br>
    </p>
  </body>
</html>

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