<x3v0-pgsql@xxxxxxxxx> writes: > I'm looking into PostgreSQL. Coming from a MySQL > background, I have made heavy use of its very useful > GROUP_CONCAT function. You can read about the function > here: > http://dev.mysql.com/doc/refman/4.1/en/group-by-functions.html > Is there a PostgreSQL alternative to GROUP_CONCAT? In Postgres it's customary to build this sort of thing out of spare parts. The basic spare part is a user-defined aggregate. You can make an aggregate over the built-in concatenation function: CREATE AGGREGATE concat ( BASETYPE = text, SFUNC = textcat, STYPE = text ); This does the basic task of concatenating the values found in a table group, but it doesn't supply any separator, so more likely you'd want to write a custom function that inserts a separator and then aggregate with that: create function textcatspace(text,text) returns text as $$ select $1 || ' ' || $2 $$ language sql strict immutable; CREATE AGGREGATE concat ( BASETYPE = text, SFUNC = textcatspace, STYPE = text ); (NB: the "strict" bit is essential to get this to match MySQL's semantics for NULLs in group_concat.) We don't unfortunately have any easy way to pass in different separator values --- you'd need to create a distinct function and aggregate for each separator string you want. Also, a function in plpgsql might be more efficient than one in SQL. The other part this isn't handling is controlling the order in which the inputs are concatenated. You can find that discussed in the archives: http://archives.postgresql.org/pgsql-general/2005-09/msg00034.php regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
