一个大查询或多个小查询哪个更好？
which is better one big query or multiple small query?
哪个更好更高效？一个大查询然后只处理 php 或 php 函数中获取的查询将只创建一个查询小数据的循环函数。还请考虑 table 可能很大（数以千计的原始数据）。谢谢
评论table
id | parent | msg
---+--------+---------
1 | 0 | hello
2 | 1 | hi
3 | 2 | whats up
4 | 3 | yow
5 | 1 | hellow
6 | 2 | nice
7 | 0 | great
预期输出是这样的：
Array
(
[0] => Array
(
[id] => 1
[parent] => 0
[value] => hello
[child] => Array
(
[0] => Array
(
[id] => 2
[parent] => 1
[value] => hi
[child] => Array
(
[0] => Array
(
[id] => 3
[parent] => 2
[value] => whats up
[child] => Array
(
[0] => Array
(
[id] => 4
[parent] => 3
[value] => yow
)
)
)
[1] => Array
(
[id] => 6
[parent] => 2
[value] => nice
)
)
)
[1] => Array
(
[id] => 5
[parent] => 1
[value] => hellow
)
)
)
[1] => Array
(
[id] => 7
[parent] => 0
[value] => great
)
As a rule of thumb, the less queries the better.
这是一个很好的问题，但已经回答了多次。
Is it better to return one big query or a few smaller ones?
Multiple small queries vs a single long query. Which one is more efficient?
One big query vs. many small ones?
What is faster, a big joined query with more PHP or multiple small selects with less PHP?
Should I use one big SQL Select statement or several small ones?
https://dba.stackexchange.com/questions/76973/what-is-faster-one-big-query-or-many-small-queries
哪个更好更高效？一个大查询然后只处理 php 或 php 函数中获取的查询将只创建一个查询小数据的循环函数。还请考虑 table 可能很大（数以千计的原始数据）。谢谢
评论table
id | parent | msg
---+--------+---------
1 | 0 | hello
2 | 1 | hi
3 | 2 | whats up
4 | 3 | yow
5 | 1 | hellow
6 | 2 | nice
7 | 0 | great
预期输出是这样的：
Array
(
[0] => Array
(
[id] => 1
[parent] => 0
[value] => hello
[child] => Array
(
[0] => Array
(
[id] => 2
[parent] => 1
[value] => hi
[child] => Array
(
[0] => Array
(
[id] => 3
[parent] => 2
[value] => whats up
[child] => Array
(
[0] => Array
(
[id] => 4
[parent] => 3
[value] => yow
)
)
)
[1] => Array
(
[id] => 6
[parent] => 2
[value] => nice
)
)
)
[1] => Array
(
[id] => 5
[parent] => 1
[value] => hellow
)
)
)
[1] => Array
(
[id] => 7
[parent] => 0
[value] => great
)
As a rule of thumb, the less queries the better.
这是一个很好的问题，但已经回答了多次。
Is it better to return one big query or a few smaller ones?
Multiple small queries vs a single long query. Which one is more efficient?
One big query vs. many small ones?
What is faster, a big joined query with more PHP or multiple small selects with less PHP?
Should I use one big SQL Select statement or several small ones?
https://dba.stackexchange.com/questions/76973/what-is-faster-one-big-query-or-many-small-queries