sql query to get earliest date

Question

If I have a table with columns id  name  score  date  and I wanted to run a sql query to get the record where id   2 with the earliest date in the data set     Can you do this within the query or do you need to loop after the fact   I want to get all of the fields of that record

User · Answer

While using TOP or a sub-query both work, I would break the problem into steps:

Find target record

SELECT MIN( date ) AS date, id
FROM myTable
WHERE id = 2
GROUP BY id

Join to get other fields

SELECT mt.id, mt.name, mt.score, mt.date
FROM myTable mt
INNER JOIN
( 
   SELECT MIN( date ) AS date, id
   FROM myTable
   WHERE id = 2
   GROUP BY id
) x ON x.date = mt.date AND x.id = mt.id

While this solution, using derived tables, is longer, it is:

Easier to test
Self documenting
Extendable

It is easier to test as parts of the query can be run standalone.

It is self documenting as the query directly reflects the requirement ie the derived table lists the row where id = 2 with the earliest date.

It is extendable as if another condition is required, this can be easily added to the derived table.

User · Answer

SELECT TOP 1 ID  Name  Score   Date  FROM myTable WHERE ID   2 Order BY  Date

User · Answer

Try  select   from dataset where id   2 order by date limit 1   Been a while since I did sql  so this might need some tweaking

User · Answer

If you just want the date   SELECT MIN date  as EarliestDate FROM YourTable WHERE id   2   If you want all of the information   SELECT TOP 1 id  name  score  date FROM YourTable WHERE id   2 ORDER BY Date   Prevent loops when you can  Loops often lead to cursors  and cursors are almost never necessary and very often really inefficient

User · Answer

Using  limit  and  top  will not work with all SQL servers  for example with Oracle   You can try a more complex query in pure sql   select mt1 id  mt1  name   mt1 score  mt1  date  from mytable mt1 where mt1 id 2 and mt1  date    select min mt2  date   from mytable mt2 where mt2 id 2

[sql] sql query to get earliest date

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