Обсуждение: text + text
What is "text + text" supposed to do right now? It doesn't seem very useful to me. What about making "text + text" as an equivalent for "text || text"? Most strongly-typed programming languages do this. And MS SQL Server too, I think (CMIIW). -- dave
Am Freitag, 8. Oktober 2004 12:57 schrieb David Garamond: > What is "text + text" supposed to do right now? Nothing. > What about making "text + text" as an equivalent for "text > || text"? Most strongly-typed programming languages do this. And MS SQL > Server too, I think (CMIIW). What would this gain except for bloat? It's not like SQL is utterly compatible with any programming language; users will still have to learn all the operators anyway. -- Peter Eisentraut http://developer.postgresql.org/~petere/
Peter Eisentraut wrote: >>What is "text + text" supposed to do right now? > > Nothing. Then are these bugs? (7.4.5 and 8.0.0beta1 give same results). Frankly, the current behaviour is quite strange to me. ------------------ =# select coalesce('1'+'0','NULL'); a =# select coalesce('1'+'1','NULL'); b =# select coalesce('1'+'3','NULL'); d =# select coalesce('a'+'0','NULL'); =# select coalesce('a'+'1','NULL'); =# select coalesce('a'+'3','NULL'); =# select coalesce('a'+'x','NULL'); Ù ------------------ >>What about making "text + text" as an equivalent for "text >>|| text"? Most strongly-typed programming languages do this. And MS SQL >>Server too, I think (CMIIW). > > What would this gain except for bloat? It's not like SQL is utterly > compatible with any programming language; users will still have to learn all > the operators anyway. I personally don't consider this "bloat". We already have other synonyms like '!=' and '<>'. '+' is very natural to mean concatenation for strings. Anyway, either emitting an error or string concatenation is better than the current behaviour, I think. -- dave
On Fri, 8 Oct 2004, David Garamond wrote: > Peter Eisentraut wrote: > >>What is "text + text" supposed to do right now? > > > > Nothing. > > Then are these bugs? (7.4.5 and 8.0.0beta1 give same results). Frankly, > the current behaviour is quite strange to me. > > ------------------ > =# select coalesce('1'+'0','NULL'); > a That isn't text+text. It's "char"+"char". "char" is a rather bizarre type being partially 1 byte integer and partially 1 character string and it causes strange behaviors like the above where I believe it's taking the first bytes of the '1' and '0' and adding them together. I think Tom was talking about removing the math operators from it so that things like the above don't happen.
David Garamond <lists@zara.6.isreserved.com> writes: > Peter Eisentraut wrote: >>> What is "text + text" supposed to do right now? >> >> Nothing. > Then are these bugs? (7.4.5 and 8.0.0beta1 give same results). Frankly, > the current behaviour is quite strange to me. CVS tip gives regression=# select coalesce('1'+'0','NULL'); ERROR: operator is not unique: "unknown" + "unknown" HINT: Could not choose a best candidate operator. You may need to add explicit type casts. regression=# See http://archives.postgresql.org/pgsql-hackers/2004-10/msg00041.php regards, tom lane