Richard Huxton wrote:
Madison Kelly wrote:
Hi all,
I've got a query that looks through a table I use for my little
search engine. It's something of a reverse-index but not quite, where
a proper reverse index would have 'word | doc1, doc3, doc4, doc7'
showing all the docs the keyword is in, mine has an entry for eac
I've got a query like:
SELECT
sch_id, sch_for_table, sch_ref_id, sch_instances
FROM
search_index
WHERE
(sch_keyword LIKE '%digi%' OR sch_keyword LIKE '%madi%')
AND
sch_for_table!='client'
AND
... (more restrictions)
ORDER BY
sch_instances DESC;
This returns references to a data column (sch_ref_id) in a given
table (sch_for_table) for each matched keyword.
The problem I am having is that two keywords might reference the
same table/column which would, in turn, give me two+ search results
pointing to the same entry.
What I would like to do is, when two or more results match the same
'sch_ref_id' and 'sch_for_table' to merge the results. Specifically,
the 'sch_instances' column is the number of times the given keyword is
found in the table/column. I'd like to add up the number in the
duplicate results (to give it a higher accuracy and move it up the
search results).
You'll want something like:
SELECT
sch_id, sch_for_table, sch_ref_id,
SUM(sch_instances) AS tot_instances
...
GROUP BY
sch_id, sch_for_table, sch_ref_id
ORDER BY
tot_instances DESC;
The key word to search the manuals on is "aggregates" (sum(), count() etc).
This is *exactly* the pointer I needed, thank you!
Sad thing is that I even used "GROUP BY" before... had just forgotten
about it. ^_^;
Madison
---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
