Re: SELECT DISTINCT problems
От | Tom Lane |
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Тема | Re: SELECT DISTINCT problems |
Дата | |
Msg-id | 18169.983374500@sss.pgh.pa.us обсуждение исходный текст |
Ответ на | SELECT DISTINCT problems (SCAHILL KEVIN <9726209@student.ul.ie>) |
Список | pgsql-sql |
SCAHILL KEVIN <9726209@student.ul.ie> writes: > I have tried this but it does not work: > Set rsLecturers = Server.CreateObject("ADODB.Recordset") > sqlLect = "Select LecturerName, MIN(ProjectCode) from tblSuggestions WHERE > LecturerName IN ( SELECT DISTINCT LecturerName FROM tblSuggestions)" > rsLecturers.Open sqlLect, Conn, 3, 3 You seem to be trying to re-invent the notion of GROUP BY. The correct way to write this sort of query in SQL is Select LecturerName, MIN(ProjectCode) from tblSuggestions GROUP BY LecturerName This gives you one output row for each distinct value of LecturerName, and within that row the MIN() aggregates over all the original rows that have that LecturerName. See http://www.postgresql.org/devel-corner/docs/postgres/query-agg.html http://www.postgresql.org/devel-corner/docs/postgres/queries.html#QUERIES-GROUP regards, tom lane
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