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1 | 1 | <!-- |
2 | | -$PostgreSQL: pgsql/doc/src/sgml/trigger.sgml,v 1.35 2004/03/03 22:22:24 neilc Exp $ |
| 2 | +$PostgreSQL: pgsql/doc/src/sgml/trigger.sgml,v 1.36 2004/08/13 16:17:19 tgl Exp $ |
3 | 3 | --> |
4 | 4 |
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5 | 5 | <chapter id="triggers"> |
@@ -431,8 +431,10 @@ typedef struct Trigger |
431 | 431 | </para> |
432 | 432 |
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433 | 433 | <para> |
434 | | - A trigger function must return either <symbol>NULL</> or a |
435 | | - <structname>HeapTuple</> pointer. Be careful to return either |
| 434 | + A trigger function must return either a |
| 435 | + <structname>HeapTuple</> pointer or a <symbol>NULL</> pointer |
| 436 | + (<emphasis>not</> a SQL NULL, that is, do not set isNull true). |
| 437 | + Be careful to return either |
436 | 438 | <structfield>tg_trigtuple</> or <structfield>tg_newtuple</>, |
437 | 439 | as appropriate, if you don't want to modify the row being operated on. |
438 | 440 | </para> |
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