SUM with group by return error [duplicate]

Question

This question already has answers here:

ORA-00979 not a group by expression (10 answers)

Closed 9 years ago.

Having this two table

DEPARTMENT

//DEPARTMENT
D#          DNAME
-------------------
1         RESEARCH
2            IT
3          SCIENCE

PROJECT

//PROJECT
P#       D#        BUDGET
-------------------------
1001     1         22500
1002     1         22500
1003     3         50000

When i execute this command

SELECT d.D#,DNAME,sum(budget) as "TOTAL BUDGETS" 
    FROM DEPARTMENT d,PROJECT p 
WHERE d.D# = p.D#
GROUP BY d.D#;

I thought result will be

D#     DNAME     TOTAL BUDGETS
------------------------------
1     RESEARCH       45000
2        IT             0
3       SCIENCE      50000

but why i get this error

//Oracle: NOT A GROUP BY EXPRESSION ERROR

Answer 1

All column names in SELECT list must appear in GROUP BY clause unless name is used only in an aggregate function.

Change query to:

SELECT d.D#,DNAME,sum(budget) as "TOTAL BUDGETS" 
    FROM DEPARTMENT d,PROJECT p 
WHERE d.D# = p.D#
GROUP BY d.D#, DNAME;

---

Update for the comment:

SELECT d.D#, d.DNAME, NVL(SUM(p.budget), 0) as "TOTAL BUDGETS" 
    FROM DEPARTMENT d LEFT OUTER JOIN PROJECT p ON d.D#=p.D#
GROUP BY d.D#, d.DNAME;

Answer 2

SELECT d.D#,max(DNAME),sum(budget) as "TOTAL BUDGETS" 
    FROM DEPARTMENT d,PROJECT p 
WHERE d.D# = p.D#
GROUP BY d.D#;

You should either include the field in GROUP BY section or use aggregate function (MAX or MIN is ok for the case)

Answer 3

You forget to declare the d.DNAME column in the GROUP BY statement:

SELECT d.D#,d.DNAME,sum(BUDGET) as "TOTAL BUDGETS" 
    FROM DEPARTMENT d,PROJECT p 
WHERE d.D# = p.D#
GROUP BY d.D#, d.DNAME;

SQLFiddle Example

If you want to display all departments, you need to use the LEFT JOIN

SELECT d.D#,d.DNAME,sum(BUDGET) as "TOTAL BUDGETS" 
    FROM DEPARTMENT d
LEFT JOIN PROJECT p
ON d.D# = p.D#
GROUP BY d.D#, d.DNAME;

SQLFiddle Example

To display 0 if no projects are present you need to use the CASE statement

SELECT d.D#,d.DNAME,
CASE WHEN sum(BUDGET) IS NULL
    THEN 0
    ELSE sum(BUDGET) END AS "TOTAL BUDGETS" 
FROM DEPARTMENT d
LEFT JOIN PROJECT p
ON d.D# = p.D#
GROUP BY d.D#, d.DNAME;

Output:

   D#   DNAME   TOTAL BUDGETS
    2   IT  0
    1   RESEARCH    45000
    3   SEARCH  50000

SQLFiddle Example