SQLite - DISTINCT Keyword


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SQLite DISTINCT keyword is used in conjunction with SELECT statement to eliminate all the duplicate records and fetching only the unique records.

There may be a situation when you have multiple duplicate records in a table. While fetching such records, it makes more sense to fetch only unique records instead of fetching duplicate records.

Syntax

Following is the basic syntax of DISTINCT keyword to eliminate duplicate records.

SELECT DISTINCT column1, column2,.....columnN 
FROM table_name
WHERE [condition]

Example

Consider COMPANY table with the following records.

ID          NAME        AGE         ADDRESS     SALARY
----------  ----------  ----------  ----------  ----------
1           Paul        32          California  20000.0
2           Allen       25          Texas       15000.0
3           Teddy       23          Norway      20000.0
4           Mark        25          Rich-Mond   65000.0
5           David       27          Texas       85000.0
6           Kim         22          South-Hall  45000.0
7           James       24          Houston     10000.0
8           Paul        24          Houston     20000.0
9           James       44          Norway      5000.0
10          James       45          Texas       5000.0

First, let us see how the following SELECT query returns duplicate salary records.

sqlite> SELECT name FROM COMPANY;

This will produce the following result.

NAME
----------
Paul
Allen
Teddy
Mark
David
Kim
James
Paul
James
James

Now, let us use DISTINCT keyword with the above SELECT query and see the result.

sqlite> SELECT DISTINCT name FROM COMPANY;

This will produce the following result, where there is no duplicate entry.

NAME
----------
Paul
Allen
Teddy
Mark
David
Kim
James


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