Learn to work with Distinct Function in MySql

In a table, some of the columns may contain duplicate values. This is not a problem, however, sometimes you will want to list only the different (distinct) values in a table. The DISTINCT statement can be used to return only distinct (different/that don'trepeat) values.

Syntax :

Select distinct(column name) from table_name ;
Let's create the table we will use

Script:

--first lets drop the table Test (if she exists, if not skip the drop line).
Drop table test;
create table test (id int,name varchar(20),email varchar(20),salary int ,de char(2));
--insert values into table
insert into test values (1,'Eve','[email protected]',1500,'HR');
insert into test values (2,'Jon','[email protected]',2500,'AD');
insert into test values (3,'Mike','[email protected]',3000,'AD');
insert into test values (4,'Paul','[email protected]',3200,'HR');
insert into test values (5,'Mary','[email protected]',1800,'IT');
insert into test values (6,'Jane','[email protected]',2200,'IT');
Check the table to see the data and the structure 
SQLselect * from test ;
    ID NAME         EMAIL            SALARY  DE
 ---------- -------------------- -------------------- ---------- --  --------
     1  Eve         [email protected]        1500   HR
     2  Jon         [email protected]        2500   AD
     3  Mike       [email protected]        3000   AD
     4  Paul        [email protected]        3200   HR
     5  Mary       [email protected]        1800   IT
     6  Jane        [email protected]       2200   IT
Very good

Distinct() examples:

Example 1:

-let's see how many distinct ID's values we have: 
SQLselect distinct(id) from test;
    ID
 ----------
     1
     6
     2
     4
     5
     3

Example 2:

-now let's see how many distinct DE (departments) we have in our test table; 
SQLselect distinct(de) from test;
DE
--
AD
IT
HR
-so we can see that thaw we have 6 rows in our table the distinct() function only shows the distinct values of DE column. We can use conditions and other functions in the same statement with distinct() function. For more on this function in future tutorials.

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