000r
a
dstocki
dex24r
otstockma
r
stock
umberbetwee
20a
d100r
stock
umberi
102030r
orderbystockiddescasc排序，desc降序，asc升序r
orderby12by列号r
stock
ameselectstock
amefromstock_i
formatio
wherestockid4r
子查询r
除非能确保内层select只返回一个行的值，r
否则应在外层where子句中用一个i
限定符r
selectdisti
ctcolum
_
ameformtable_
amedisti
ct指定检索独有的列值，不重复r
selectstock
umber