Correct usage description of Oracle join

The following articles mainly introduce the correct usage of Oracle join through code. The actual application proportion of Oracle join is still the majority. If you use this newly developed technology, if you are curious, the following articles will unveil its mysteries. I hope you will gain some benefits after browsing.

 
 

  
  
8i:  
  
  
create table dali.test1(a int,b int);  
  
  
create table dali.test2(a int,b int);  
  
  
insert into dali.test1 values(1,456);  
  
  
insert into dali.test1 values(2,427);  
  
  
insert into dali.test2 values(1,45456);  
  
  
insert into dali.test2 values(3,45656);  
 
 

Internal Connection

 
 

  
  
select * from dali.test1 a, dali.test2 b where a.a=b.a; 
 
 

Left join

 
 

  
  
select * from dali.test1 a, dali.test2 b where a.a=b.a(+); 
 
 

Right join

 
 

  
  
select * from dali.test1 a, dali.test2 b where a.a(+)=b.a; 
 
 

Full connection

 
 

  
  
select * from dali.test1 a, dali.test2 b where a.a=b.a(+)  
  
  
union  
  
  
select * from dali.test1 a, dali.test2 b where a.a(+)=b.a; 
 
 

Dikar

 
 

  
  
select * from dali.test1, dali.test2;  
  
  
'================================================================== 
 
 

9i is the same as sqlserver left join, right join, full join

Divided into 1. inner join 2. left join 3. right join 4. LEFT OUTER JOIN

First, set the two tables we want to use.

Table A Table B

ID NAME ID CLASS

1 IBM 1 C1

2 SONY 3 C3

3 BMW 4 C4

1 inner join: SELECT * from a inner join B on a. ID = B. ID

Table ID NAME CLASS

1 IBM C1

3 BMW C3

By the way, the IDs of both tables exist and the combined tables of the two tables are obtained.

2 left join: SELECT * from a left join B on a. ID = B. ID

Table ID NAME CLASS

1 IBM C1

2 SONY null

3 BMW C3

If there is A sense of direction, LEFT (left) returns A (LEFT table of left Statement) and table B does not have any records! Haha)

3 right join: SELECT * from a right join B on a. ID = B. ID

Table ID NAME CLASS

1 IBM C1

3 BMW C3

4 null C4

RIGHT (right) returns all records of B (table on the RIGHT side of the right statement). If the records of Table A do not exist, they must be completed (I have turned over too! Haha)

4 full outer join: SELECT * from a full outer join B on a. ID = B. ID

Table ID NAME CLASS

1 IBM C1

2 SONY null

3 BMW C3

4 null C4

The above content describes the usage of Oracle join, hoping to help you in this regard.