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I have mutliple workers SELECTing and UPDATing row.
id status
10 new
11 new
12 old
13 old
Worker selects a ‘new’ row and updates its status to ‘old’.
What if two workers select same row at the same time?
I mean worker1 selects a new row, and before worker one updates its status, worker2 selects the same row?
Should I SELECT and UPDATE in one query or is there another way?
You could LOCK the table before your read, and unlock it after your write. This would eliminate the chance of two workers updating the same record at the same time.
http://dev.mysql.com/doc/refman/5.0/en/lock-tables.html