Hello,
I'm attempting to use monetdb for some temporal queries. Some queries require the output to be coalesced. For example, with schema emp(empno int, ts date, te date) the tuples (00001, '1/1/2001', '2/1/2001'), (00001, '2/1/2001', '3/1/2001') are output as (00001, '1/1/2001', '3/1/2001').
My coalescing query works in both MS SQL Server and DB2 but MonetDB gives me the error "SELECT: no such column 'm.ts'". 1) A leaner alternative query form using window clauses (ROWS UNBOUNDED PRECEDING) doesn't appear to be supported in MonetDB. So I'm stuck. Any help would be appreciated.
Query: WITH Emps(empno, ts, te) AS (SELECT empno, ts, te FROM emp) SELECT DISTINCT F.empno, F.ts, L.te FROM Emps AS F, Emps AS L WHERE F.ts < L.te AND F.empno = L.empno AND NOT EXISTS (SELECT * FROM Emps AS M WHERE M.empno = F.empno AND F.ts < M.ts AND M.ts < L.te AND NOT EXISTS (SELECT * FROM Emps AS T1 WHERE T1.empno = F.empno AND T1.ts < M.ts AND M.ts <= T1.te) ) AND NOT EXISTS (SELECT * FROM Emps AS T2 WHERE T2.empno = F.empno AND ((T2.ts < F.ts AND F.ts <= T2.te) OR (T2.ts <= L.te AND L.te < T2.te)) );
Thanks, Alex