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    <p>This concerns the <a href="http://www.postgresql.org/docs/current/interactive/plpgsql-control-structures.html#PLPGSQL-CONDITIONALS" rel="nofollow noreferrer">conditional control structure <code>CASE</code></a> of the <a href="https://www.postgresql.org/docs/current/static/plpgsql.html" rel="nofollow noreferrer">procedural language PL/pgSQL</a>, to be used in <a href="https://www.postgresql.org/docs/current/static/sql-createfunction.html" rel="nofollow noreferrer">plpgsql functions</a> or <a href="http://www.postgresql.org/docs/current/interactive/sql-do.html" rel="nofollow noreferrer"><code>DO</code> statements</a>. Not to be confused with the <a href="http://www.postgresql.org/docs/current/interactive/functions-conditional.html#FUNCTIONS-CASE" rel="nofollow noreferrer"><code>CASE</code> expression of SQL</a>. Different language! And subtly different syntax rules, too. </p> <p>While SQL <code>CASE</code> can be embedded in SQL expressions inside PL/pgSQL code (which is mostly just glue for SQL commands), you cannot have stand-alone SQL <code>CASE</code> expressions (would be nonsense).</p> <pre><code>-- inside plpgsql code block: CASE WHEN old.applies_to = 'admin' THEN _applies_to := 'My Self'; ELSE _applies_to := initcap(old.applies_to); END CASE; </code></pre> <p>You have to use fully qualified statements, terminated with semicolon (<code>;</code>) and <code>END CASE</code> to close it.</p> <h3>Answer to <a href="https://stackoverflow.com/questions/8924035/postgresql-case-usage-in-functions/8924119#comment11167507_8924119">additional question in comment</a></h3> <p>According to documentation the <code>ELSE</code> keyword of a <code>CASE</code> statement is <strong>not</strong> optional. I quote from the link above:</p> <blockquote> <p>If no match is found, the <code>ELSE</code> statements are executed; but if <code>ELSE</code> is not present, then a <code>CASE_NOT_FOUND</code> exception is raised.</p> </blockquote> <p>However, you can use an empty <code>ELSE</code>:</p> <pre><code>CASE WHEN old.applies_to = 'admin' THEN _applies_to := 'My Self'; ELSE -- do nothing END CASE; </code></pre> <p>This is different from SQL <code>CASE</code> expressions where <code>ELSE</code> is optional, but if the keyword is present, an expression has to be given, too!</p>
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    1. USErwin Brandstetter
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    1. COThank you very much for your quick support Erwin. Very much appreciate it.
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      1. USYohan Hirimuthugoda
    2. COAnother small question Erwin. Accroding to documentation ELSE condition of CASE statement is optional. But when I try to run series of WHEN conditions with statements without ELSE, Query browser giving me errors. `ERROR: case not found. HINT: CASE statement is missing ELSE part.` If you need I'll post relevant script part.
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    3. CO@Yohan: Please see additional answer.
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