How could I delete sql functions format in awk? - sql

Question

I've got a sql query which looks like this:
SELECT test1(func1(MYFIELD)),
test2(MAX(MYFIELD), LOWER("NOPE")),
test3(MAX(MYFIELD), 1234),
AVG(test1(test2(MYFIELD, func1(4)))),
func2(UPPER("stack"))
SUBSTR(MYFIELD, 2, 4),
test2(MIN(MYFIELD), SUBSTR(LOWER(UPPER("NOPE")), 1, 7)),
SUBSTR('func1(', 2, 4)
FROM MYTABLE;
Then I'm trying to remove all functions called:
test1
test2
test3
func1
func2
But preserving the AVG, MAX, UPPER, SUBSTR... and all native functions.
So the desired output would be:
SELECT MYFIELD,
MAX(MYFIELD),
MAX(MYFIELD),
AVG(MYFIELD),
UPPER("stack")
SUBSTR(MYFIELD, 2, 4),
MIN(MYFIELD)
SUBSTR('func1(', 2, 4)
FROM MYTABLE;
I want to remove the LOWER of the second line because, it is an argument of one of the functions to delete, in this case test2, which has two parameters. Then if we delete the function, we should delete its params as well.
I've tried to do it by this way in awk:
{
print gensub(/(test1|test2|func1|func2)\(/,"","gi", $0);
}
But the output doesn't have into account the right parentheses, it doesn't also delete the rest of parameters of the custom functions:
SELECT MYFIELD)),
MAX(MYFIELD), LOWER("NOPE")),
MAX(MYFIELD), 1234),
AVG(MYFIELD, 4)))),
UPPER("stack"))
SUBSTR(MYFIELD, 2, 4),
MIN(MYFIELD), SUBSTR(LOWER(UPPER("NOPE")), 1, 7)),
SUBSTR('', 2, 4)
FROM MYTABLE;
Any idea or clue to handle this situation?

Answer 1

you could just rename functions' names to built-in functionCOALESCE while keep the brakets ( ) and other params of users' functions.
It will produce the same result, not syntactically, but it will work the same UNLESS the built-in functions don't return NULL values. It will be much easier to achieve because you don't have to worry about brakets.
If file is an input you provide, then:
cat file | sed 's#\(test1\|test2\|func1\|func2\)(#COALESCE(#g'
will produce:
SELECT COALESCE(COALESCE(MYFIELD)),
COALESCE(MAX(MYFIELD), 4),
AVG(COALESCE(COALESCE(MYFIELD, COALESCE(4)))),
COALESCE(UPPER("stack"))
FROM MYTABLE;