Help with some sql queries

Question

Hi, I have a few queries which I'm having difficulty in executing and I'm not sure where I'm going wrong. Here are the tables and their columns:
AGENTS (AGENT_ID (num), LOCATION_ID (num), FIRST_NAME (varchar2), LAST_NAME (varchar2), SECURITY_LEVEL (num), BIRTH_DATE (date), ACTIVATION_DATE (date), DEACTIVATION_DATE (date)).
MISSIONS_AGENTS (MISSION_ID (num), AGENT_ID (num)).
MISSIONS (MISSION_ID (num), LOCATION_ID (num), SECURITY_LEVEL (num)).
MISSION_TARGETS (MISSION_ID (num), TARGET_ID (num)).
TARGETS (TARGET_ID (num), LOCATION_ID (num), FIRST_NAME (varchar2), LAST_NAME (varchar2), BIRTH_DATE (date)).
INFORMATION (INFORMATION_ID (num), AGENT_ID (num), GLEANED_DATE (date), SECURTIY_LEVEL (num), TARGET_ID (num)).
ACCESS_COST (COST_ID (num), LOWER_BOUND_LEVEL (num), UPPER_BOUND_LEVEL (num), COST (num)).
LOCATIONS (LOCATION_ID (num), DESCRIPTION (varchar2)).
The schema represents all of the relevant information for a secret government agency. The AGENTS table contains information on employees of the agency. MISSIONS regards the missions those agents are sent on. TARGETS contains information on non-agency people encountered on missions. On the course of missions, these targets provide information that goes into the INFORMATION table. LOCATIONS is a list of places where both agents and targets are based and where missions take place. MISSION_TYPES contains the different types of mission.
MISSIONS_AGENTS is the linking tables for the many-to-many relationship between MISSIONS and AGENTS. This is needed because one agent can go on many missions, and many agents can be involved in a single mission. There is a similar relationship between targets and missions, hence the MISSIONS_TARGETS linking table.
One table isn't linked to the others - the ACCESS_COST table. This table tells the database how much money to charge when someone accesses the INFORMATION table, based on the SECURITY_LEVEL of the information. You can find out how much a piece of information is worth by seeing which bracket of LOWER_BOUND_LEVEL and UPPER_BOUND_LEVEL it lies between. Note that the highest UPPER_BOUND_LEVEL is defined as NULL to allow for indefinitely high security levels. Similarly, the bottom LOWER_BOUND_LEVEL is also defined as NULL.
Q1. Develop a query which will return agents and the total amount each spent on accessing information with a security level between 2 and 3.
Create a table from the query called ‘ONE’ with columns FIRST_NAME, LAST_NAME and SPENT.
Q2. For those deactivated agents that are on more than seven missions, change their deactivation date to the earliest deactivation date of all agents who were activated in the same year as the agent you are updating.(this does make sense if you think about it!).
Now create a copy of your updated AGENTS table called ‘TWO’.
Q3. Return the agents that are not on a mission. (Provide two different solutions). Create a table to hold the information called ‘THREE’. It should contain a single column NAME to hold the agent's full name. Alphabetise the table.
Q4. Return the locations by top ten associated information cost. Define 'associated information cost' as follows: each piece of information that comes from a target living in a location adds to that location's information cost.
Note that your query should account for the fact that two locations may have the same cost - were this the case, your query should return eleven values (not just ten) and the locations should all be in the range of the top ten costs. Create a table to hold these results called ‘FOUR’ with columns LOCATION_ID and COST. Put the data in descending order of cost.

Answer 1

ok this is what I've done so far but the queries don't work
--Q1
CREATE TABLE ONE
AS
SELECT A.FIRST_NAME, A.LAST_NAME,
SUM(AC.COST) SPENT
FROM AGENTS A
INNER JOIN
INFORMATION I
ON A.AGENT_ID=I.AGENT_ID
INNER JOIN
ACCESS_COST AC
ON I.SECURITY_LEVEL BETWEEN 2 AND 3
GROUP BY
A.FIRST_NAME, A.LAST_NAME
ORDER BY
SUM(AC.COST)
SELECT *
FROM ONE
--Q2
UPDATE AGENTS A
SET
A.DEACTIVATION_DATE =
SELECT *
FROM
SELECT MIN(A1.DEACTIVATION_DATE)
FROM AGENTS A1
INNER JOIN
MISSIONS M
ON A1.AGENT_ID = MA.AGENT_ID
WHERE     MA.MISSION_ID > 7
AND     A.DEACTIVATION_DATE,'YYYY' =
     A.ACTIVATION_DATE, 'YYYY'
CREATE TABLE TWO
AS
SELECT *
FROM AGENTS
SELECT *
FROM TWO
--Q3
CREATE TABLE THREE
AS
SELECT A.LAST_NAME||' '||A.FIRST_NAME NAME
FROM AGENTS A
INNER JOIN
MISSIONS_AGENTS MA
ON
     A.AGENT_ID = MA.AGENT_ID
WHERE
     MA.MISSION_ID = 0
ORDER BY
     A.LAST_NAME||' '||A.FIRST_NAME
SELECT *
FROM THREE
CREATE TABLE THREE
AS
SELECT
     A.LAST_NAME||' '||A.FIRST_NAME NAME
FROM AGENTS A
INNER JOIN
MISSIONS_AGENTS MA
ON
     A.AGENT_ID = MA.AGENT_ID
WHERE
     MA.MISSION_ID < 1
ORDER BY
     A.LAST_NAME||' '||A.FIRST_NAME
SELECT *
FROM THREE
--Q4
CREATE TABLE FOUR
AS
SELECT
     LOCATION_ID, COST
FROM
SELECT
     L.LOCATION_ID LOCATION,
     T.LOCATION_ID + I.INFORMATION_ID COST
FROM
     INFORMATION I
INNER JOIN
     TARGETS T
ON
     I.TARGET_ID = T.TARGET_ID
INNER JOIN
     LOCATIONS L
ON
     T.LOCATION_ID = L.LOCATION_ID
ORDER BY
     T.LOCATION_ID + I.INFORMATION_ID DESC
WHERE
     ROWNUM < 11
SELECT *
FROM FOUR
;