Am Dienstag, 6. Mai 2008 schrieb Daniel Schuchardt: > so it depends on ? if i need an explicit cast? A type cast can be attempted in three different contexts (see also CREATE CAST reference page): - implicitly - storage assignment - explicitly The explicit case is if you call CAST() or ::. This is always allowed if an appropriate cast routine is defined. The implicit case is if an operator or function requires type A and the expression is of type B. This cast is only performed if the cast routine is defined and allowed for the implicit context. The change in 8.3 was to "downgrade" many casting functions from implicit to assignment or explicit. The storage assignment case is if the value has type A and is about to be stored into a column of type B. This is allowed if the cast routine is allowed for the assignment context. This is, perhaps surprisingly, a separate level between implicit and explicit casts. So in reference to your subject line, yes, INSERT and UPDATE do have different casting behavior than SELECT. (This is not really accurate, because the WHERE clause of an UPDATE would follow the same rules as a WHERE clause in SELECT. The assignment context only applies for values that are really going to be stored.) This is all in line with the SQL standard.
