select * from table1,table2 where table1.sn=table2.sn(+)我想知道最后面的（+）是什么意思

select * from table1,table2 where table1.sn=table2.sn(+)我想知道最后面的（+）是什么意思 select count(*) from table1 select count(*) from table2 select count(*) from table3我从table1 table2 table3 中 找数据的条数怎样一下子用一条sql语句 算出TABLE1 TABLE2 TABLE3 记录的总和? 多表查询的不同方式的区别select a.* from table1 a,table2 b where a.id = b.id 与 select a.* from table1 a inner join table2 b on a.id = b.id 的区别.具体分析两种的性能及原理! select * from book limit , sql server 2000 grant select on table1 to @logname提示to @logname语法错误其中@logname为局部变量 谁能给我解释一下as的用法阿select id,column1 * column2 as column from table1谁明白这个语句的意思?希望把as的用法讲的明白些不是英语里面的as用法,是asp里面的用法 select * from a union select * from b 能详细说下么 select from 表 和select from [表]有什么不同? select count(*) from 怎么使用 select count(1) from emp select * into dept2 from dept 1' union select * from [ADM] union select * 请问 select top 1 1 from ... // IF EXISTS (SELECT name FROM m select * into b from a where 11 SQL 语句 SELECT * FROM {{table}} WHERE `fleet_end_time` SELECT ms sql :select * from (select *from b) as xxx where 和 select * from (select *from b) xxx where区select * from (select *from b) as xxx where…… 和 select * from (select *from b) xxx where……的区别别告诉我是一样的.因为我有一