组内的mysql限制？

我想限定组内记录的巨细,这是我的试用版,怎样做到对差池？

mysql> select * from accounts limit 5 group by type;

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual
that corresponds to your MySQL server version for the
right syntax to use near ‘group by type’ at line 1

前提：account_balance的特定帐户范例的前5位

SELECT account_type,account_balance FROM accounts WHERE account_type='savings' 
   ORDER BY account_balance DESC LIMIT 5
UNION
SELECT account_type,account_balance FROM accounts WHERE account_type='chequing' 
   ORDER BY account_balance DESC LIMIT 5
UNION
SELECT account_type,account_balance FROM accounts WHERE account_type='USD' 
   ORDER BY account_balance DESC LIMIT 5;

它并不大度,但假如您行使剧本结构SQL,则在account_types中举办子搜刮并将查询毗连在一路是很简朴的.

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