There are a few ways depending on what version you have – see the oracle documentation on string aggregation techniques. A very common one is to use LISTAGG: SELECT pid, LISTAGG(Desc, ‘ ‘) WITHIN GROUP (ORDER BY seq) AS description FROM B GROUP BY pid; Then join to A to pick out the pids you … Read more
Since 9.0 this is even easier: SELECT id, string_agg(some_column, ‘,’) FROM the_table GROUP BY id
No REAL easy way to do this. Lots of ideas out there, though. Best one I’ve found: SELECT table_name, LEFT(column_names , LEN(column_names )-1) AS column_names FROM information_schema.columns AS extern CROSS APPLY ( SELECT column_name + ‘,’ FROM information_schema.columns AS intern WHERE extern.table_name = intern.table_name FOR XML PATH(”) ) pre_trimmed (column_names) GROUP BY table_name, column_names; Or … Read more
PostgreSQL 9.0 or later: Modern Postgres (since 2010) has the string_agg(expression, delimiter) function which will do exactly what the asker was looking for: SELECT company_id, string_agg(employee, ‘, ‘) FROM mytable GROUP BY company_id; Postgres 9 also added the ability to specify an ORDER BY clause in any aggregate expression; otherwise you have to order all … Read more