sql在查询中选择最大日期

Question

I have a query like this

SELECT DISTINCT
FND.ID_CON,
SPRT.CODE,
SPRT.NOM,
SPRT.DATE_VALUE,
COTPLACE.LIBELLE
FROM
FND,
SPRT,
CONTRACT,
COTPLACE
WHERE
FND.code=SPRT.code
and FND.cot_place=SPRT.cot_place
and FND.cot_place=COTPLACE.cot_place(+)
and FND.origine=SPRT.origine
and FND.ID_CON=CONTRACT.ID_CON
and FND.ORIGINE=CONTRACT.ORIGINE
and SPRT.code = '12345678' 
and CONTRACT.ID_CON like '%ABC123%'

....

this query returns two lignes with different DATE_VALUE how to select only the line with max DATE_VALUE? Thanks

Answer 1

You can use max :

select nom, prenom, max(date_empl)
from your_table
where your_condition
group by nom, prenom

Answer 2

You can use order by + LIMIT 1 :

select nom, prenom, date_empl
from person, employ, enterprise
where person.id= "test"
and person.id= emploi.id
and person.enterpriseName = enterprise.name
order by date_empl DESC LIMIT 1

Answer 3

THIS ANSWERS THE ORIGINAL VERSION OF THE QUESTION.

This assumes that you mean that you get multiple rows for the same nom / prenom combination. One typical method is:

select p.nom, p.prenom, max(e.date_empl)
from person p join
     employ em
     on p.id = em.id 
where p.id = 'test'
group by p.nom, p.prenom;

The enterprise table would not seem to be needed for this query.

Notes:

• Never use commas in the FROM clause. Always use proper explicit JOIN syntax.
• Use table aliases that are abbreviations for table names.
• Always qualify column names (especially in a query that references more than one table).
  • Don't use tables that are not needed.

If you just want one row returned, you would use ORDER BY and some way of limiting the results. The ANSI standard method is:

select p.nom, p.prenom, e.date_empl
from person p join
     employ em
     on p.id = em.id 
where p.id = 'test'
order by e.date_empl desc
fetch first 1 row only;