Hi, I am studying SQL at the mom and can deal with most simple query. I am having problems with more complex ones like joining tables etc. A prime example is the following

3 tables

CREATE TABLE Student
(RegNo NUMBER
CONSTRAINT PK_Student PRIMARY KEY,
Name VARCHAR2(20)
CONSTRAINT NOT_NULL_Student_Name NOT NULL) ;

CREATE TABLE Unit
(UnitCode CHAR(4)
CONSTRAINT PK_Unit PRIMARY KEY,
Name VARCHAR2(20)
CONSTRAINT NOT_NULL_Unit_Name NOT NULL) ;

CREATE TABLE Result
(UnitCode CHAR(4)
CONSTRAINT FK_Result_Unit REFERENCES Unit,
Regno NUMBER
CONSTRAINT FK_Result_Regno REFERENCES Student,
AcadYear NUMBER
CONSTRAINT NOT_NULL_Acad_Year NOT NULL,
Percent NUMBER,
CONSTRAINT PK_Result PRIMARY KEY
(UnitCode,Regno,AcadYear)) ;

Query = Show the average marks for each student, listing the students by their Names

My attempt=

SELECT name, AVG(Percent)
FROM Student s, Result r
WHERE s.Regno = r.Regno
ORDER BY s.name

I know this is wrong but could someone tell me Y

Thanks.

check your manual for the difference between ORDER BY and GROUP BY