1. What is the value of the NEW variable for a column that is not mentioned
in an UPDATE statement? Is it NULL? If not NULL, what?
For example, given this table:
my_tbl (id integer, att1 varchar, att2 varchar)
and a row-wise ON UPDATE OR INSERT trigger function containing this
conditional:
IF NEW.att2 IS NULL THEN
<do stuff>
END IF;
and this UPDATE query:
UPDATE my_tbl SET att1 = 'foo' where id = 1;
will that conditional be satisfied?
2. Same questions re the value of a NEW variable that is not assigned a
value in an INSERT statement.
For example, how would the previous conditional behave in response to:
INSERT INTO my_tbl (id) VALUES (1);
?
3. If an UPDATE query set a column to DEFAULT, what value does a trigger
function see for the column's NEW variable? Is it the string 'DEFAULT', a
reserved word DEFAULT, an empty string, or what?
For example, what would you put in place of <??> in this UPDATE trigger
function:
IF NEW.att2 <??> THEN
<do stuff>
END IF;
to get it to <do stuff> in response to this UPDATE query:
UPDATE my_tbl SET att2 = DEFAULT where id = 1;
?
~ TIA
~ Ken
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