SQL statement Check the data of two tables Urgent!!

Another way to look: select ,select zy ,sum(zy as yjjefrom zy tbkk,zy brry

where zy_ = zy_

group by zy_

t1,select zy_,sum(zy_ as fyzsfrom zy_fymx,zy_brry

where zy_ = zy_

group by zy_;

t2where ;

Above, I hope it will help you.

Actually, it's not an accumulation, but that there is no unique correspondence between the two tables you are associated with.

SQL statements are no problem, see if there are any duplicates in the zyh table in the zy brry table.

sum(zy What you use here is accumulation, so the data found out is cumulative!

If you use sum, it will be accumulated, and the main consideration is sum

Use a where statement to perform a query, for example:

select, from emp, company where, but often encounter more complex statements, at this time it is not appropriate to use where, in fact, sql can be connected in a more direct form, can be pointed out in a direct form in the from clause:

select top 10 e_id,e_name,c_namefrom emp join companey onwhere

e_id not in (select top 20 e_id from emp order by e_id asc)

order by e_id asc

The data from 21 to 30 in the EMP query table are sorted in ascending order, where the c name comes from another table.

1. The statement is as follows:

select project.*,contract].*from project

left join contract_project on = contract_

left join [contract] on contract_ = contract].contractid

Note: Contract is a keyword in SQL Server, so parentheses are used.

2. Use left join

The left join is based on the left table. In other words, all records in the left table (project) will be displayed, while the right table (contract project) will only display records that match the search criteria.

In this example, it is: = contract. For contract tables, the contract project table is the left table.

In this example, three tables are joined together conditionally with two left joins.

Tools Raw materials.

Computer sqlserver2008

Method steps.

1. Check the student number, name, course name and grades of all students who choose courses. Query statements.

2. The query result appears.

3. Query the names and age queries of all students older than Zhao Xue.

4. The query result appears.

select a.*

from Cadet Table A

Inner Join Campus Table B on ASchool = BSchool.

Inner Join Admin Table c on BRegion=cRegion.

where c.username=@用户名 and cpassword = @密码.

select a.*

from Cadet Table A

Inner Join Campus Table B on ASchool = BSchool Inner Join Admin Form c on B

Region=cArea where cusername=@用户名 and c

password = @密码. Extended MaterialsIn SQL Server, you can use Join On [Inner Join On] to associate multi-table queries.

select ,from cyb

join xa on =

join bg on =

where ( and = 121) or ( and = 118)

If you want to judge whether the logical relationship is correct, you can use the following**:

select ,from , b,where and

For example, there are now three tables:

Administrator table: username, password, region.

Student List: Name, Gender, Student Number, School.

Campus List: School, Region.

Now to query a complete piece of information, you can write an SQL statement in this way:

select * from Administrator Form A, Cadet Table B, Campus Table C where aRegion=cArea and bSchool = CSchool.

Note: You can replace * with the field of the table you want to search, but it must be prefixed, for example, if you want to check the username in the administrator table, you can write aUsername.

select * from Learner Table where School=(select School from School Member, Table where Region=(select Region from Administrator Table where username='Enter' Stable password='Enter')).

select a.*

from Cadet Table Bai A

Inner Join Campus Table B on ASchool = BSchool Inner Join Admin Form c on B

Region=cArea where cUse the du account name zhi=@用户名 and c

password = @密码.

First of all, I suggest that you do it separately from the list query, both from a security and implementation standpoint!

After logging in, use the session to store the area information, and then query the select learner table as follows. * from Cadet Table, Campus Table, where Cadet Table. Campus = Campus Table. The school district.

Of course, you have to do it directly.

select the learner table. * from Cadet Table, Campus Table, Administrator Table, where Learner Table. Campus = Campus Table.

Campus and Campus Chart. Region = Administrator table. Region where username = ?

and password = ?

If you write like this, it is recommended to do a security check, otherwise, it is easy to be injected into the attack.