SQL: Does a Field Exist?

In the FoxPro world, checking to see if a field exists can be done a number of ways:

=AFIELDS(la)
IF ASCAN(la,"FIELDNAME")>0

ENDIF

or

IF TYPE("FIELDNAME") = "U"

(I'm sure there are lots of other ways especially if you're already working with a data dictionary tool)

In T-SQL, there is no real equivalent however, you can do the same by using the INFORMATION_SCHEMA table.

While there is no shortage of sites on the web that will show you similar code (like this one), I wanted to post it here for any VFP devs who may be switching between DBFs and SQL.

IF NOT EXISTS( SELECT * FROM INFORMATION_SCHEMA.COLUMNS
WHERE INFORMATION_SCHEMA.COLUMNS.TABLE_NAME = 'MyTable'
AND COLUMN_NAME='MyColumn')
ALTER TABLE myTable ADD MyColumn decimal(10,2) NULL

Of course, this assumes that the table already exists but you can use similar approaches for tables as well.

IF NOT EXISTS(SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_NAME = 'myTable')
CREATE TABLE .....

if NOT EXISTS(SELECT TABLE_NAME FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'CFG_Fees'
AND COLUMN_NAME='minmFee')
ALTER TABLE .....


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