select substr(tm_smp,1,12),count(tm_smp)
from transreorder
group by substr(tm_smp,1,12);
不过,如果你的表很大,而且这个操作进行的很频繁,可以考虑在tm_smp列上建函数索引。函数就是sub(tm_smp,1,12).
同时把代码改为试试:
select substr(tm_smp,1,12),count(substr(tm_smp,1,12))
from transreorder
group by substr(tm_smp,1,12);
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