MySQL Select rows on first occurrence of each unique value

Question

Let\'s say you have the following table (the column of interest here is cid):

+-----+-------+-------+-------+---------------------+-------------         


        

Answer 1

In MySQL 8, you would use window functions for this

SELECT cid, pid, rid, clink, time, snippet
FROM (
  SELECT t.*, ROW_NUMBER() OVER (PARTITION BY cid ORDER BY time) rn
  FROM t
) t
WHERE rn = 1