Selezionare TOP 1 dal set di risultati

Question

Vorrei recuperare il valore di 1 parte superiore del set di risultati di ricerca che è collegata tramite dell'Unione

SELECT TOP 1 * FROM 
(
    SELECT paused_time as end_time 
     FROM production_time 
     WHERE created_time = curdate() 
    UNION 
    SELECT resumed_time as end_time 
     FROM pause_timer 
     WHERE created_time = curdate() 
    UNION 
    SELECT end_time as end_time 
     FROM timer_idle 
     WHERE created_time = curdate() 
) as end_time 
ORDER BY end_time DESC 

Ma non ha potuto ottenere il risultato atteso.

Answer 1

Non esiste una parola chiave TOP in MySQL per quanto ne so. Quello che ti serve è Limit:

SELECT * FROM 
(
    SELECT paused_time as end_time FROM production_time WHERE created_time = curdate() 
    UNION 
    SELECT resumed_time as end_time FROM pause_timer WHERE created_time = curdate() 
    UNION 
    SELECT end_time as end_time FROM timer_idle WHERE created_time = curdate() 
) as end_time 
ORDER BY end_time DESC 
LIMIT 1