Query in sql

Question

oracle database version 10.2.0.1 on windows server 2003
segment_id is a common column in two tables "segment" and "mv_cat_seg_reg_prod"
mv_cat_seg_prod can have more than a single row for each segment_id
whereas segment table has one row for each segment_id(not more than one)
segment_id column in the segment table is not sequential
segid
1
2
5
8
78
again:for a single segment_id there may be one or more rows
i need to count number of rows in mv_cat_seg_reg_prod for each segment_id
there are thousands of segments so how do i count
select count(*) from mv_cat_seg_reg_prod where segment_id=first segment_id of segmentid column of segment table
select count(*) from mv_cat_seg_reg_prod where segment_id=second segment_id of segmentid column of segment table
select count(*) from mv_cat_seg_reg_prod where segment_id=third segment_id of segmentid column of segment
table
select count(*) from mv_cat_seg_reg_prod where segment_id=fourth segment_id of segmentid column of segment table
and so on
please help me automate it
thanks in advance

Answer 1

Hi,
Join the two tables.
If you want to include results for all values in the segment table, even if they have 0 matching rows in mv_cat_seg_reg_prod, then make it an outer join, like this:
SELECT       s.segment_id
,       COUNT (m.segment_id)     AS cnt
,       ROW_NUMBER () OVER (ORDER BY  s.segment_id)
                                AS r_num     -- if wanted
FROM           segment           s
LEFT OUTER JOIN      mv_cat_seg_reg_prod  m  ON  m.segment_id = s.segment_id
GROUP BY  s.segment_id
ORDER BY  s.segment_id
I hope this answers your question.
If not, post a little sample data (CREATE TABLE and INSERT statements, relevant columns only) for all tables involved, and also post the results you want from that data. If any of your tables are views (materialized or otherwise) then pretend they're actaully real tables, and post CREATE TABLE and INSERT statemnts that mimic the relevnt columns in the vies.
Explain, using specific examples, how you get those results from that data.
Always say which version of Oracle you're using (e.g., 11.2.0.2.0).
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