Mysql查询问题

Question

SELECT substring(rd_shipment_sample_shipping_month,1,7) FROM rd_shipment_sampletracking group by substring(rd_shipment_sample_shipping_month, 1 ,7) order by rd_shipment_sample_shipping_month

Answer 1

SELECT concat_ws('-',year(rd_shipment_sample_shipping_month),month(rd_shipment_sample_shipping_month)) FROM rd_shipment_sampletracking group by concat_ws('-',year(rd_shipment_sample_shipping_month),month(rd_shipment_sample_shipping_month))  order by rd_shipment_sample_shipping_month
这样也可以。

Answer 2

select distinct left(rd_shipment_sample_shipping_month,7) from rd_shipment_sampletracking

Answer 3

没想到把substring(string, 0, 7)改成substring(string, 1, 7)就可以了  谢谢大家！！！！！！！！！！