Check if FIELD exists on a table? 1

[diarmaid]

How can I check if a particular table has a field of a specific name ? If I find it doesn't exist I need to create it using ALTER TABLE

Many thanks,

Diarmaid

 

[Neil Toulouse]

Check the AFIELDS() function. This will build an array of your table structure. You can then loop through the array checking for the existence of your field name.

Neil

I like work. It fascinates me. I can sit and look at it for hours...

 

[diarmaid]

Many thanks, I also found an earlier thread on this question and it was interesting. Also, I have found reference to the functions field() and fcount()

fcount() is the total number of fields in a table, so one can loop through them by number 1 to fcount(), also,

field(i) will return the field name

Diarmaid

 

[StewartUK]

I wold suggest the following in a function, program or method:

LPARAMETERS MyField
AFIELDS(TblFields)
RETURN ASCAN(TblFields, MyField)

That's the basics - as it is it would work on whatever table or cursor is open in the current work area.

It could be improved by adding a 2nd parameter for a table-name (with the option to work on the current area if no table-name is received). If you were to do that, remember to add code to change work area before opening the new table and to return to the current work area afterwards.

I had a look at DBGETPROP & CURSORGETPROP but they don't appear to do what you want.

Hope that helps,

Stewart
PS If you want to get the best response to a question, please check out FAQ184-2483 first.

 

[Olaf Doschke]

You may simply try:

select 0
use mytable in 0 exclusive
if type("mytable.mynewfield") # cTypeexpected
   alter table mytable add mynewfield ...
endif

Bye, Olaf.

 

[albertdc]

Another one suggestion would be to use

FSIZE(fieldname)

If it returns 0, it does not exist.