Hoon Hoon - 1 year ago 106
MySQL Question

auto increment by specific column's data

In a table like below,

category | feeds | content
1 1 something
1 2 bar
1 3 foo
2 1 blah
2 2 um
1 4 things

How should I do to work auto_increment independently (distinguished by 'category')?

Thanks in advance.

Answer Source

When it comes to oracle we have ROW_NUMBER() OVER PARTITION BY statement but for Mysql it is still tricky to implement this one. As most probably we will use this implementation to limit data either descending/ascending order across groups.

Here you go with the similar implementation for your reference:

SELECT @row_number:=CASE WHEN @category=category 
THEN @row_number+1 ELSE 1 END AS feeds,@category:=category AS category, content
FROM table1, (SELECT @row_number:=0,@category:='') AS t
ORDER BY category;

SQLFiddle Link

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