CODEWITHSUNDEEP
sqlsql-servert-sql
TheObserver
TheObserver

Reputation: 3021

Getting the most recent entry per group in a select statement

I have 3 tables to join to get table1.code, table1.series, table2.entry_date, table3.title1 and I'm trying to get the most recent non null table3.title1 grouped by table1.code and table1.series.

select table1.code, table1.series, max(table2.entry_date), table3.Title1 
                from table3 INNER JOIN table2 ON  table3.ID = table2.ID
                INNER JOIN table1 ON table2.source_code = table1.code
                where table3.Title1 is not NULL 
                group by table1.code, table1.series, table3.Title1

seems to give me all entries with a non null title1 instead of the most recent one. How should I structure the query to just pick the newest version of Title1 per code & series?

Upvotes: 3

Views: 965

Answers (3)

Chris Bednarski
Chris Bednarski

Reputation: 3424

;with tlb as
(
    select table1.code, table1.series, table2.entry_date, table3.Title1,
    row_number() over(code, series, entry_date order by code, series, entry_date desc) as rn
    from table3 INNER JOIN table2 ON table3.ID = table2.ID 
    INNER JOIN table1 ON table2.source_code = table1.code 
    where table3.Title1 is not NULL
)
select * from tlb where rn = 1

This can be very quick depending on your indexes.

Upvotes: 0

Robin Day
Robin Day

Reputation: 102568

Maybe something like this to join on only the most recent of the table2 entries?

SELECT
    table1.code,
    table1.series,
    table2.entry_date,
    table3.Title1
FROM
    table1
INNER JOIN
    table2
ON
    table2.source_code = table1.code
AND
    table2.entry_date =
(
    SELECT
        MAX(maxtable2.entry_date)
    FROM    
        table2 maxtable2
    WHERE
        maxtable2.source_code = table2.source_code
)
INNER JOIN
    table3
ON
    table3.ID = table2.ID

Upvotes: 0

codingbadger
codingbadger

Reputation: 44042

Try this:

select table1.code, table1.series, max(table2.entry_date), max(table3.Title1) as Title1
from table3 
INNER JOIN table2 ON  table3.ID = table2.ID
INNER JOIN table1 ON table2.source_code = table1.code
where table3.Title1 is not NULL 
And Table2.entry_Date = (Select Max(sq.entry_Date)
                        From sq.table2
                        Where sq.id = table2.ID)
group by table1.code, table1.series

Upvotes: 3

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