Oracle: Concatenate string

 Prepare data:

 

CREATE TABLE student

 ( "ID" VARCHAR2(4 BYTE) primary key,
 "FIRST_NAME" VARCHAR2(10 BYTE),
 "LAST_NAME" VARCHAR2(10 BYTE)
   );

 

Use the command 'describe student' to see the newly created table student's data structure.

 

describe student;

 

The output is:

 

describe student
Name       Null     Type        
---------- -------- ------------
ID         NOT NULL VARCHAR2(4) 
FIRST_NAME          VARCHAR2(10)
LAST_NAME           VARCHAR2(10)

Insert into student(ID,FIRST_NAME,LAST_NAME) values ('1','Jason','Martin');

Insert into student(ID,FIRST_NAME,LAST_NAME) values ('02','Alison','Mathews');

Insert into student(ID,FIRST_NAME,LAST_NAME) values ('03','James','Smith');

 

commit;

 

select * from student;

 

The output is:

 

ID                    FIRST_NAME               LAST_NAME

1                      Jason                            Martin

2                      Alison                            Mathews

3                      James                           Smith

 

Then if we want to see the student id, and their full name with the format of 'first_name.last_name',

 

we can use the following sql to concatenate string of the two columns named first_name and last_name:

 

select id, first_name || '.' || last_name as full_name from student;

 

The output is:

 

ID             FULL_NAME

1               Jason.Martin

2               Alison.Mathews

3              James.Smith

 

In this way , you can concatenate 2 columns as 1 column with specified format to display the result.