On Tue, Feb 18, 2025 at 7:06 AM David G. Johnston <david.g.johns...@gmail.com> wrote: > > On Tue, Jan 21, 2025 at 11:29 PM jian he <jian.universal...@gmail.com> wrote: >> >> in 9.7.2 do you think it's worthwhile changing it to >> >> "" >> As with SIMILAR TO, substring(string, pattern, escape-character) >> the specified pattern must match the entire data string, or else the >> function fails and returns null. >> "" >> ? >> > > Making reference to any one of the three listed function signatures here > doesn't seem to provide value. If anything I'd write: > > "As with SIMILAR TO, substring matches the specified pattern to the entire > data string, returning null otherwise." > > I would avoid saying that the function fails in any situation that doesn't > produce an actual error. The transition of "match everything or returns > null" can be bike-shedded though. >
thinking about it. I think the current wording "As with SIMILAR TO, the specified pattern must match the entire data string, or else the function fails and returns null" is fine. I guess my complaint is that the above sentence is not as explicit as the 9.7.3 section description. " The substring function with two parameters, substring(string from pattern), provides extraction of a substring that matches a POSIX regular expression pattern. It returns null if there is no match, otherwise the first portion of the text that matched the pattern. "
