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.