May 16, 2021 SQLite
SQLite's GROUP BY clause is used with SELECT statements to group the same data.
In the SELECT statement, the GROUP BY clause is placed after the WHERE clause and before the ORDER BY clause.
The basic syntax of the GROUP BY clause is given below. The GROUP BY clause must be placed after the conditions in the WHERE clause and before the ORDER BY clause.
SELECT column-list FROM table_name WHERE [ conditions ] GROUP BY column1, column2....columnN ORDER BY column1, column2....columnN
You can use more than one column in the GROUP BY clause. Make sure that the groups you use are listed in the column list.
Suppose the COMPANY table has 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
If you want to know the total salary per customer, you can use the GROUP BY query, as follows:
sqlite> SELECT NAME, SUM(SALARY) FROM COMPANY GROUP BY NAME;
This results in the following:
NAME SUM(SALARY) ---------- ----------- Allen 15000.0 David 85000.0 James 10000.0 Kim 45000.0 Mark 65000.0 Paul 20000.0 Teddy 20000.0
Now, let's create three more records in the COMPANY table using the following INSERT statement:
INSERT INTO COMPANY VALUES (8, 'Paul', 24, 'Houston', 20000.00 ); INSERT INTO COMPANY VALUES (9, 'James', 44, 'Norway', 5000.00 ); INSERT INTO COMPANY VALUES (10, 'James', 45, 'Texas', 5000.00 );
Our table now has a record of duplicate names, as follows:
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
Let's group all records by NAME column with the same GROUP BY statement, as follows:
sqlite> SELECT NAME, SUM(SALARY) FROM COMPANY GROUP BY NAME ORDER BY NAME;
This results in the following:
NAME SUM(SALARY) ---------- ----------- Allen 15000 David 85000 James 20000 Kim 45000 Mark 65000 Paul 40000 Teddy 20000
Let's use the ORDER BY clause with the GROUP BY clause, as follows:
sqlite> SELECT NAME, SUM(SALARY)
FROM COMPANY GROUP BY NAME ORDER BY NAME DESC;
This results in the following:
NAME SUM(SALARY) ---------- ----------- Teddy 20000 Paul 40000 Mark 65000 Kim 45000 James 20000 David 85000 Allen 15000