sql manual: Example of conditions added

git-svn-id: https://svn.osgeo.org/grass/grass/branches/releasebranch_7_0@65874 15284696-431f-4ddb-bdfa-cd5b030d7da7

lib/db/sqlp/sql.html

@@ -187,6 +187,18 @@ v.db.update mygeodetic_pts col=zval \
 v.db.update vectormap column=column3 qcolumn="column1 || column2"
 </pre></div>
 
+<h3>Example of conditions</h3>
+
+Conditions (like if statements) are usually written as CASE statement in SQL:
+
+<div class="code"><pre>
+v.db.update vectormap column=species qcolumn="CASE WHEN col1 &gt;= 12 THEN cat else NULL end"
+
+# a more complex example with nested conditions
+v.db.update vectormap column=species qcolumn="CASE WHEN col1 &gt;= 1 THEN cat WHEN row = 13 then 0 ELSE NULL end"
+</pre></div>
+
+
 <h2>SEE ALSO</h2>
 
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