某公司数据库面试题

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In database XYZ, there's a table 'run_key' with the following rows:

id batch last_processed
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1  5           999
2 6           999
3  7             0
4  5             0
5  6           999
6  7             0
7  5             0
8  6             0
9 7           999
10 7             0

batch count
-------------
5             2
6             1
7             3

[sql] 
select batch,count(batch) as count from run_key where last_processed=0 group by batch;