select * from table1,table2 where table1.row=table2.row(2)自连接select * from emploly e1 ,emploly e2select e1.name,e2.name from employ e1,employ e2where e1.name=e2.name(3)内连接(inner join)select stuname as '姓名',classname as '班级' from student inner join class on student....
select * from table1 insert into table2 （通常的写法是 select * into table2 from table1）要求目标表table2 不存在，因为在插入时会自动创建表table2 ，并将table1 中指定字段数据复制到table2 中 因为table2不存在所以不能插入常量insert into table2 select * from table1 要求table2已存在...
1、增加一个表table3，字段为id，name，主键id 2、table1、table2分别增加一个外键字段nameid，来自于table3的id 3、 select * from table1 t1, table2 t2 where t1.nameid= t2.nameid 比如t1中有name值为a，然后t2中有name值a跟b，当t1值比较t2值时，a=a数据不输出，a=b数据输出，表...
SELECT column_name(s)FROM table_name1 LEFT JOIN table_name2 ON table_name1.column_name=table_name2.column_name 注：LEFT JOIN 关键字会从左表 (table_name1) 那里返回所有的行，即使在右表 (table_name2 ) 中没有匹配的行。
如果table1中的某行的对应id值在table2中存在，那么table1的该行将被查询出。这句语句是合法的，比如table1中存在id值1 2 3的记录， table2中存在id值为2 3 5的记录，那么执行这句后，table1中的2 3两条记录将被查询到。如果这并不是想要得到的效果，那么需要修改SQL语句。select...
select * from table1 a,table2 b其中的a，b就是把table1，table2 命名为a，b 之后调用table1，table2的数据就方便多了 比如原本要调用table1，table2的数据需要table1.id，table2.id 而命名之后就可以a.id b.id 方便了sql的读写功能 有问题欢迎追问 a...
Is there anyway or a sql statement that can do something like, Select * from table1 where table1 not in table2. which means i get all the rows in table1, as long as they r not in table2 All replies (2) Saturday, May 21, 2005 12:14 AM ...
Re: SELECT * FROM table1,table2 Theo Tonge October 15, 2005 01:08PM Re: SELECT * FROM table1,table2 Trayko Stoilov October 15, 2005 03:01PM Re: SELECT * FROM table1,table2 Trayko Stoilov October 15, 2005 03:53PM Sorry, you can't reply to this topic. It has been closed....
table1的值中age1的值也有11，那么就查询出来；但是table2中如果有值2134，table1中的age1并不存在...
SELECTt1.name, t2.salaryFROMemployeeASt1INNERJOINinfoASt2ONt1.name=t2.name;SELECTt1.name, t2.salaryFROMemployee t1INNERJOINinfo t2ONt1.name=t2.name; 2.2 table_subquery也称为FROM子句中的派生表或子查询。Section 13.2.10.8, “Derived Tables”. ...