Php+mysql Data Query Tips

A table with cat_id field, query time,

Cat_id=1, find 5 Records,
cat_id=2, find 5,
Cat_id=3, find 5,
......
Cat_id=n, find out 5 strips.
......

Such a query requires that
In addition to the circular Select, is there a more efficient approach?

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A table with cat_id field, query time,

Cat_id=1, find 5 Records,
cat_id=2, find 5,
Cat_id=3, find 5,
......
Cat_id=n, find out 5 strips.
......

Such a query requires that
In addition to the circular Select, is there a more efficient approach?

What are you trying to find out? is the number of records, or some fields of the record?

GROUP BY CAT_ID can
CAT_ID in () can also be

The loop select must not work, so the performance is too poor, can order by cat_id, so that the results of cat_id order,
Then make a map of the results , cat_id the same in a map

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