一个大查询还是多个小查询哪个更好? [英] which is better one big query or multiple small query?
问题描述
哪个更好，更有效?一个大查询然后仅在php中或从php函数中处理获取的查询，将创建一个查询小数据的循环函数.还请考虑该表可能很大(成千上万个原始表).谢谢.
评论表
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
预期输出为:
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
)
根据经验，查询越少越好.
这是一个很好的问题，但已被多次回答.
什么是更快的，包含更多PHP的大型联合查询或包含更少PHP的多个小型选择?
我应该使用一个大的SQL Select语句还是几个小的语句?
https://dba.stackexchange .com/questions/76973/what-is-faster-one-big-query-or-many-small-queries
https://dba.stackexchange.com/questions/35277/is-it-更好地将一个大查询分离成多个较小的查询
which is better and efficient? one big query then just process the fetched query in the php or from php function will just create a loop function that queries small data. Please consider also that the table can be big (thousands of raw). Thanks.
Comments 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
Expected output is this:
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.
This is a good question but this has been answered multiple times.
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?
Which one is faster single big query or few small queries?
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
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