[SQL] Parsing a Calculation from a field

[Kieran Ashley]

Hi,   Apologies if this is the wrong list for this question, I hope it’s not.   I’m porting an application to PostgreSQL, and rewriting a number of transforms used to convert incoming Excel data into a final Postgres table schema for an application.  Most of it’s gone okay, but there’s one column giving me trouble.   Some of our data comes in in a format which provides us with extra information, but which we currently don’t need to use; specifically we sometimes receive information in the form of calculations, for example a column which needs to be transformed to an integer is initially of type varchar, and contains values like:   6 10 2 4 + 8 2 + 4 + 8 NULL 4   I need to come up with some code that can somehow treat the contents of this field as a potential sum, and execute that if necessary – something along the lines of ‘select exec(FIELDNAME) from TABLE’.   I could obviously add an extra step to the procedure and write a script using something like PHP to scan the table and carry out any necessary calculations in advance, but I’m curious to know if there is a way within Postgres to do it either as part of the select query itself, or as a PL/SQL procedure.  I’ve had a quick look at the string handling functions but I can’t see any way to parse integers out of a varchar column – which would seem to prohibit using substring to manually break up the sums.   Any help on this would be greatly appreciated.   Kieran Note: The information contained in this email and any subsequent correspondence is private and is intended solely for the intended recipient(s). For those other than the intended recipient(s) any disclosure, copying, distribution, or any action taken or omitted to be taken in reliance on such information is prohibited and may be unlawful.