[SOLVED] PostgreSQL Selecting Most Recent Entry for a Given ID

PostgreSQL Selecting Most Recent Entry for a Given ID

Table Essentially looks like:

Serial-ID, ID, Date, Data, Data, Data, etc.

There can be Multiple Rows for the Same ID. I'd like to create a view of this table to be used in Reports that only shows the most recent entry for each ID. It should show all of the columns.

Can someone help me with the SQL select? thanks.

Solution

There's about 5 different ways to do this, but here's one:

SELECT *
FROM yourTable AS T1 
WHERE NOT EXISTS(
    SELECT *
    FROM yourTable AS T2
    WHERE T2.ID = T1.ID AND T2.Date > T1.Date
)

And here's another:

SELECT T1.*
FROM yourTable AS T1
LEFT JOIN yourTable AS T2 ON
(
    T2.ID = T1.ID 
    AND T2.Date > T1.Date
)
WHERE T2.ID IS NULL

One more:

WITH T AS (
    SELECT *, ROW_NUMBER() OVER(PARTITION BY ID ORDER BY Date DESC) AS rn
    FROM yourTable
)
SELECT * FROM T WHERE rn = 1

Ok, i'm getting carried away, here's the last one I'll post(for now):

WITH T AS (
    SELECT ID, MAX(Date) AS latest_date
    FROM yourTable
    GROUP BY ID
)
SELECT yourTable.*
FROM yourTable
JOIN T ON T.ID = yourTable.ID AND T.latest_date = yourTable.Date