Indexes is a good idea but I already have the relevant columns already indexed. The count is there to sequence the same brands like: 
id brand rank=(count*)
1  A     1
2  B     1
3  A     2
4  A     3
5  B     2
...

[download]
etc. That way the dates from consecutive brand appearances can be compared by the rank=rank+1 for the datediff() comparison. There already is an autoincrement id column but it can't be used for comparing consecutive dates of the same brand.

In reply to Re^4: find difference in dates/items in same column by zerocred
in thread find difference in dates/items in same column by zerocred

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