Php MySQL选择名称按字母分组限制为每个字母n个结果
我想创建一个查询,从一个表中获取名称,然后将其与其他表合并,按字母表中每个字母的字母顺序排列,然后在一个查询中限制每个字母的结果为n 因此,我不想对每个字母运行26个查询,比如:Php MySQL选择名称按字母分组限制为每个字母n个结果,php,mysql,sql,Php,Mysql,Sql,我想创建一个查询,从一个表中获取名称,然后将其与其他表合并,按字母表中每个字母的字母顺序排列,然后在一个查询中限制每个字母的结果为n 因此,我不想对每个字母运行26个查询,比如: SELECT CONCAT_WS(' ',first_name,last_name) AS name FROM encyclopedia WHERE name LIKE "A%" ORDER BY rand() LIMIT 4 SELECT CONCAT_WS(' ',first_name,last_name) AS
SELECT CONCAT_WS(' ',first_name,last_name) AS name FROM encyclopedia WHERE name LIKE "A%" ORDER BY rand() LIMIT 4
SELECT CONCAT_WS(' ',first_name,last_name) AS name FROM encyclopedia WHERE name LIKE "B%" ORDER BY rand() LIMIT 4
SELECT CONCAT_WS(' ',first_name,last_name) AS name FROM encyclopedia WHERE name LIKE "C%" ORDER BY rand() LIMIT 4
现在我有:
SELECT
e.id,
CONCAT_WS(' ',first_name,last_name) AS name,
sg.name AS sub_name,
sg.id AS sub_id
FROM ( SELECT id,first_name,last_name FROM encyclopedia ORDER BY RAND() LIMIT 4) AS e
LEFT JOIN encyclopedia_subgenres esub
ON ( e.id = esub.enc_id )
LEFT JOIN subgenres sg
ON ( esub.subgenre_id = sg.id )
ORDER BY name
然后,我从php中根据结果创建数组:
Array
(
[b] => Array
(
[2] => Array
(
[name] => B Style
[genres] => Array
(
[26] => Classic
[27] => X
[29] => Y
)
)
[7] => Array
(
[name] => Beyonce Giselle Knowles
[genres] => Array
(
[32] => Pop
)
)
)
[i] => Array
(
[1] => Array
(
[name] => Ivan D
[genres] => Array
(
[27] => R&B
[2] => Jazz
)
)
)
[m] => Array
(
[3] => Array
(
[name] => Maria T
[genres] => Array
(
[26] => Classical
[27] => Pop
[28] => Dance
)
)
)
)
但问题是,它限制了我只有4个随机结果,可以是4个在同一个字母或任何组合上。
有办法做到这一点吗
谢谢。我认为sql没有那么灵活,但我不确定。您必须为此编写存储过程 首先创建一个生成此序列的序列:A,B,C,…,Z,A,B,C,…,Z,A,B,C。。。 让我们称之为魔术序列 然后创建一个临时表,其中一列init从magic sequence中播种,另一列count_down等于4。它应该有26行。让我们称之为init_table 然后编写另一个函数,即验收测试
- take a string S with
- decrease count_down of the corresponding row in init_table
- return true if count_down > = 0; otherwise false
现在有这样一个查询:
SELECT CONCAT_WS(' ',first_name,last_name) AS name FROM encyclopedia WHERE acceptance_test(name) LIMIT 4*26
如果你愿意,你也必须随机化