都说减少字段可减少下载量,从而加快查询速度,那要是把不要的数据写成,null as 字段名,可以达到同样的效果吗?
如:
select pono as 采购单号,po_date as 采购日期,po_qty as 采购数量,null as 其它1,null as 其它2,null as 其它3
from table
如:
select pono as 采购单号,po_date as 采购日期,po_qty as 采购数量,null as 其它1,null as 其它2,null as 其它3
from table
select ISNULL(colName,'the column is null') from tb
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mike
jason
the column is null--没明白lz意思