Deduplication in mysql

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About distinct keywords

select DISTINCT uid, name from zzzz;

Which really means is to remove the duplicate records, the first select uid, name from zzzz;and then filter out duplicate records, the first record retention. Therefore, the results dinstinct depends on the field you are looking for, it is not filtered out of a field.

If we only need to filter out duplicate uid it?

select uid, name from zzzz group by uid;

Or filter out duplicate uid, name

select uid, name, age from zzzz group by uid, name;