questions in SQL Oracle - sql

Question

I'm trying to answer these questions but I couldn't and I need here
1) List the number of days that have elapsed since each student joined.
this what I did
Select FR_FIRSTNAME,
FR_LASTNAME,
trunc(sysdate - FR_DATEJOINED) / 7 DAYS
from alharbi_bandar5_FRESHMEN;
no rows selected
2) List the student names and city in upper case.
This what i did
Select FR_FIRSTNAME, FR_LASTNAME, CITY FROM alharbi_bandar5_FRESHMEN
where UPPER (FR_FIRSTNAME, FR_LASTNAME, CITY) like 'SMITH%';
> where UPPER (FR_FIRSTNAME, FR_LASTNAME, CITY) like 'SMITH%'
*
ERROR at line 2:
ORA-00909: invalid number of arguments
3) List the no and last name of the student(s) with the highest ACT score.
This what i did
Select FR_NO, FR_LASTNAME, ACT from alharbi_bandar5_FRESHME
where ACT = MAX(ACT);
where ACT = MAX(ACT)
*
ERROR at line 2:
ORA-00934: group function is not allowed here
this is my table
FR_ FR_FIRSTNAME FR_LASTNAME FR_DATEJO ACT CITY
--- ------------------------------ ------------------------------ --------- ---------- ------------------------------
100 Mark Ramon 12-JUL-13 21 Florence
101 John Wright 13-JUN-13 31 Edgewood
102 Peter Sellers 06-JAN-13 30 Blue Ash
103 Eric Bates 14-MAY-13 24 Milford
104 Theresa Boyers 23-APR-13 22 Covingtion
105 Alex William 04-MAR-13 24 Edgewood
106 Eric Byrd 23-MAR-13 19 Alexandria
107 Steve Norris 21-DEC-12 21 Highland
108 Lisa Nkosi 13-FEB-13 33 Florence
109 Bradley Rego 21-FEB-12 29 Covington
110 Kathy Thomas 15-OCT-12 27 Milford
111 Catherine Jones 17-APR-13 34 Edgewood
112 Emily Hess 15-NOV-12 36 Highland
113 Josha Hunter 19-MAY-14 31 Florence

Answer 1

A lot of these questions have answers in the Oracle SQL reference and are mostly syntax issues.
1) trunc(sysdate - FR_DATEJOINED) / 7 DAYS
Oracle gies out the number of days in the units of difference, so sysdate - FR_DATEJOINED would gie you number of days, which could also involve fractional component (2.5 days for example, if it has been 2 days and 12 hours since the candidate joined). Trunc would get rid of the fractional component, but "/7" would convert the result into number of weeks instead. why are you doing this?
Either way, i don't believe this query is being fired against the table below, otherwise you'd not get zero rows as you are not filtering anything at all.
Check these out for more info on Oracle's date functions.
http://docs.oracle.com/cd/E17952_01/refman-5.1-en/date-and-time-functions.html
https://www.youtube.com/watch?v=H18UWBoHhHY
2) UPPER function accepts a column name or an expression, so if you need multiple columns. you'd need to use UPPER around each column.
3) For this example, you'll need to use a subquery to get the max value first and then use the query on top.
getting the max value
Select max(act) from alharbi_bandar5_FRESHME;
so, final query would be...
Select FR_NO, FR_LASTNAME, ACT from alharbi_bandar5_FRESHME
where ACT = (select MAX(ACT) from alharbi_bandar5_FRESHME);
Or, you could use the oracle rank function..
select fr_no,
fr_last_name,
act
from (
select fr_no, fr_lastname, act,
rank () over (order by act desc) rnk
from alharbi_bandar5_FRESHME
) where rnk = 1