Hi Josh, I think I'll follow your advice, as this is the method that I had in my pocket to use if I had no response. I tried with TRIM and other functions in the CHECK constraint, but I guess that I cannot use functions over a check field.
It surprised me, but anyway, I'll do that. Thanks a lot for your prompt reply Thrasher Josh Berkus wrote: > Thrasher, > > >>where type can be 's' for 'single' and 'x' for extended, so s should >>mean that there is only the type and data1 field, and x means that all >>fields are set. >> >>How can I set a unique constraint like CHECK (type = 's' AND UNIQUE >>(type, data1)) OR (type = 'x' AND UNIQUE (type, data1, data2)) ? >> >>The documentation says that 2 NULL values are different, so no unique >>constraint can be set over it. > > > Simple. Don't use NULLs. NULL means "unknown". You should use a > differnent value, such as a blank string or "N/A" or "000000000000000" to > represent "intentionally left blank". > > Then you can set data2 NOT NULL and use a regular UNIQUE constraint. > > BTW, you have defined your data columns as CHAR, not VARCHAR. You do know > that this implies that your data columns will be *exactly* 16 characters in > length? > ---------------------------(end of broadcast)--------------------------- TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/users-lounge/docs/faq.html
