这条SQL语句中，两表格名称之间的逗号是什么意思？

[yandw]

Select a.NameGroup,a.sName,t.number from #TMP a,(select NameGroup,max(number) as number from #TMP group by NameGroup) T where a.NameGroup=t.NameGroup and a.number =t.number;
请问语句中#TMP a,(select 中间的逗号是什么操作

[百年树人]

select a.* from a,b where a.id=b.id

[百年树人]

笛卡儿积后，再筛选

[东那个升]

这个怎么解释，SQL的语法。

[feixianxxx]

如果没有后面的where语句就是CROSS JOIN
有的话就是相当于内连接。。。

ect a.NameGroup,a.sName,t.number
 from #TMP a join (
 select NameGroup,max(number) as number from #TMP group by NameGroup) T on a.NameGroup=t.NameGroup and a.number =t.number;

[东那个升]

也可以把‘，’换成 join

[SQL77]

INNER JOIN 的另类写法

[Mr_Nice]

Select a.NameGroup,a.sName,t.number 
from #TMP a,(select NameGroup,max(number) as number from #TMP group by NameGroup) T where a.NameGroup=t.NameGroup and a.number =t.number; 

a,(select...
(select NameGroup,max(number) as number from #TMP group by NameGroup) T 就是一个子查询。相当于表。
逗号分开，只是语法要求。没有理由。要求而已。

[yandw]

谢谢大家。我就是不知道这个语法。