在运行PHP和MySQL的服务器上，使用一个PHP循环进行多个SQL调用是否更有效，反之亦然？

Question

I have a Windows Server 2012 with IIS running MySQL 5.7 and PHP 5.6. I have to build some complex JSON using multiple data sets and loops.

Would it be more efficient for me to do one SQL call and then build my JSON using a number of PHP loops on an array of data?

SQL:

SELECT stuff, item_id
FROM here
WHERE item = 1 
OR item = 2 
OR item = 3 
OR item = 4

PHP:

foreach($sql_results as $item)
{
  // build JSON by looking at $item['item_id']
}

Or would it be better for me to do each SQL call individually (in a loop of some kind) and build the JSON as the calls are being made?

SQL:

SELECT stuff, item_id
FROM here
WHERE item = 1 

SELECT stuff, item_id
FROM here
WHERE item = 2 

SELECT stuff, item_id
FROM here
WHERE item = 3 

SELECT stuff, item_id
FROM here
WHERE item = 4 

PHP:

$item
// build JSON directly from each call

With a very large amount of calls, either PHP or MySQL could get bogged down... so which one would I go with as my workhorse here?

Answer 1

The db request is definitely more time consuming, so I would choose the first approach with one SQL query and PHP loop.