Re: Parsing a Calculation from a field

How are you getting the data from Excel? Perhaps you could use Excel's own
methods to evaluate the cell contents? You may still need to do something
for literal text values (e.g. 'NULL'), though.

"Kieran Ashley" <krashley(at)space(dot)qinetiq(dot)com> wrote in message
news:6665151E3647D711B27B0090277C004F9AF681(at)ntexch02s(dot)scs(dot)dra(dot)hmg(dot)gb(dot)(dot)(dot)
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

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