使用WHERE或PHP从MySQL过滤数据？

Question

In terms of performance, what's better between select all rows from a table and then filter the results with PHP, or filter the query directly using WHERE (multiple conditions) ?

Answer 1

Using where condition is the best choice because this query will run faster that the first one. Indexes on the fields that appear in WHERE or GROUP BY or ORDER BY clauses are most of the time useful. Loading all data before filter is better that loading the filtered data :)