I'm trying to define a trigger function that looks for changes in table A (table the trigger for the function is on) and write a delta record into table B. So if a record has a value of 100 in table A, and it is updated to 50, the function should write –50 in table B. I can get the trigger to work with static SQL statements but for the actual code, I need to use dynamic SQL because I need to alter the insert statement to B depending on what column in table A is altered. I can get the correct SQL generated but when I execute the string inside the trigger function I get an error because it doesn't seem to be able to see the NEW table when it's run with EXECUTE.
So, this works in the trigger function:
Insert into A (col1,col2,…colN)
Select new.col1,new.co2…new.colN)
This doesn't:
sql := 'Insert into A (col1,col2,…colN) ';
sql := sql || 'Select new.col1,new.co2…new.colN)';
Execute sql;
ERROR: missing FROM-clause entry for table "new"
There is nothing wrong with the resulting code from sql because if I output the string and put it in as static SQL in my trigger it works.
How do I build the string within the trigger and execute it with a reference to NEW?
Thanks in advance for the help,
James