Help....on stored procedure (or package)

Question

Hi,
I have any problem to create stored procedure in Oracle, Can you help me?
I have to create a stored procedure (or package) in order to reserve the free rooms to the students in the period comprised between the DATE_START and DATE_END.
Table of the present rooms in building BL1 (RM): SEX 1 = M - SEX 2 = F SEX = 0 (ROOM WITHOUT SEX)
BL_ID.....FL_ID.......RM_ID.........SEX......RM_STD.....RM_CAT
BL1.........1..........101..............1........S........ROOM
BL1.........1..........102..............0........D........ROOM
BL1.........1..........103..............2........T........ROOM
BL1.........2..........201..............2........S........ROOM
BL1.........2..........202..............1........D........ROOM
BL1.........2..........203..............1........T........ROOM
BL1.........3..........301..............2........S........APARTMENT
BL1.........3..........302..............2........D........APARTMENT
BL1.........3..........303..............1........T........APARTMENT
BL1.........3..........304..............1........D........APARTMENT
BL1.........3..........305..............0........D........APARTMENT
Table of the students (EM):
EM_ID...........BL_ID.......FL_ID........RM_ID........COD_STUD
SABRINA..........BL1..........1............102.........524505
TAKEM............BL1..........1............103.........569673
SERAFINO.........BL1..........1............103.........589920
STELLA...........BL1..........1............102.........574659
CHIARA...........BL1..........1............101.........587845
VIDAL............BL1..........1............102.........602877
ROSARIA..........BL1..........2............202.........517070
LUCA.............BL1..........2............201.........602743
DANIELA..........BL1..........2............203.........602865
ANNAMARIA........BL1..........3............305.........588721
LUIGI............BL1..........3............304.........546517
Type of rooms (RM_STD):
RM_STD.......STD_EM........DESCRIPTION
D.............4..............DOUBLE
T.............6..............TRIPLE
S.............2..............SINGLE
Tables of the reservations carried out from the students (RMPCT):
EM_ID......BL_ID........FL_ID......RM_ID......DATE_START.......DATE_END.......COD_STUD
CHIARA......BL1.........1..........101.......11/02/2004.......12/02/2004.......587845
CHIARA......BL1.........1..........101.......03/02/2005.......16/02/2005.......587845
SERAFINO....BL1.........1..........102.......12/02/2004.......19/02/2004.......589920
VIDAL.......BL1.........1..........102.......16/02/2004.......01/03/2004.......602877
SERAFINO....BL1.........1..........103.......01/02/2004.......15/02/2004.......589920
TAKEM.......BL1.........1..........103.......04/02/2005.......10/02/2005.......569673
LUCA........BL1.........2..........201.......03/02/2005.......23/02/2005.......602743
ROSARIA.....BL1.........2..........202.......03/02/2005.......16/02/2005.......517070
DANIELA.....BL1.........2..........203.......03/02/2005.......04/02/2005.......602865
LUIGI.......BL1.........3..........301.......03/02/2005.......23/02/2005.......546517
VALERIA.....BL1.........3..........302.......12/02/2004.......16/02/2004.......515348
CHIARA......BL1.........3..........302.......05/02/2004.......15/02/2004.......587845
CHIARA......BL1.........3..........304.......10/02/2004.......12/02/2004.......587845
CHIARA......BL1.........3..........305.......20/01/2004.......04/02/2004.......587845
ANNAMARIA...BL1.........3..........305.......03/02/2005.......16/02/2005.......588721
INPUT PARAMETERS:
CREATE OR REPLACE Procedure RESERVE_ROOMS (stud_name varchar2,
cod_stud varchar2,
bl_in varchar2,
fl_in varchar2,
rm_in in varchar2,
sex_in varchar2,
date_start_in varchar2,
date_end_in varchar2)
CONDITIONS:
verify if there are students in table EM:
select count (1)
into v_appo
from em
where em_id = stud_name
and cod_stud = cod_stud;
if v_appo = 0 then
insert new student:
          insert into em (em_id,cod_sud,sex)
values (stud_name,cod_stud,sex_in);
Now I must verify the free rooms in the period comprised between the DATE_START_IN and DATE_END_IN.
I tried this query: (seem correct...have you any idea?)
select bl_id,fl_id,rm_id,RM_STD
from rm
where (bl_id,fl_id,rm_id,RM_STD) not in (select a.bl_id,a.fl_id,a.rm_id,A.RM_STD
                         from rm a, rmpct b
                         where a.bl_id=b.bl_id
                         and a.fl_id=b.fl_id
                         and a.rm_id=b.rm_id
                         AND((b.date_start <= TO_DATE(date_start_in, 'dd-mm-YYYY')
                         AND b.date_end >= TO_DATE(date_end_in, 'dd-mm-YYYY'))
                         OR ( b.date_end <= TO_DATE(date_end_in, 'dd-mm-YYYY'))
                         AND b.date_end >= TO_DATE(date_start_in, 'dd-mm-YYYY')
                         OR ( b.date_start >= TO_DATE(date_start_in, 'dd-mm-YYYY')
                         and b.date_start <= TO_DATE(date_end_in, 'dd-mm-YYYY')
                         AND b.date_end >= TO_DATE(date_end_in, 'dd-mm-YYYY'))))
with this query I get all free rooms in period date_start_in - date_end_in, but I must,also,verify if there are double or triple rooms (reserved) with minus of 2 (double) or minus of 3 (triple) students. If there are I can reserved these rooms.
I tried to verify with these steps:
CREATE OR REPLACE VIEW COUNT_EM ( BL_ID,
FL_ID, RM_ID, NUMBER_EM ) AS
(SELECT rm.bl_id, rm.fl_id, rm.rm_id, COUNT(*) as numero_em
FROM em, rm
WHERE em.bl_id(+) = rm.bl_id
AND em.fl_id(+) = rm.fl_id
AND em.rm_id(+) = rm.rm_id
and rm.rm_std in ('S', 'D', 'T')
group by rm.bl_id, rm.fl_id, rm.rm_id)
CREATE OR REPLACE VIEW COUNT_RMPCT ( BL_ID,
FL_ID, RM_ID, STD_EM, NUMBER_RMPCT
) AS
SELECT rm.bl_id, rm.fl_id, rm.rm_id, rmstd.std_em, COUNT(*) as numero_rmpct
FROM rm, rmpct,rmstd
WHERE rmpct.bl_id(+) = rm.bl_id
AND rmpct.fl_id(+) = rm.fl_id
AND rmpct.rm_id(+) = rm.rm_id
and rm.rm_std=rmstd.rm_std
and rm.rm_std in ('S', 'D', 'T')
AND((rmpct.date_start <= TO_DATE(date_start_in', 'dd-mm-YYYY')
AND rmpct.date_end >= TO_DATE(date_end_in, 'dd-mm-YYYY'))
OR ( rmpct.date_end <= TO_DATE(date_end_in, 'dd-mm-YYYY'))
AND rmpct.date_end >= TO_DATE(date_start_in, 'dd-mm-YYYY')
OR ( rmpct.date_start >= TO_DATE(date_start_in, 'dd-mm-YYYY')
and rmpct.date_start <= TO_DATE(date_end_in, 'dd-mm-YYYY')
AND rmpct.date_end >= TO_DATE(date_end_in, 'dd-mm-YYYY')))
group by rm.bl_id, rm.fl_id, rm.rm_id, rmstd.std_em
AND FINALLY:
select a.bl_id, a.fl_id, a.rm_id, a.NUMBER_RMPCT, B.NUMBER_EM, a.std_em, (a.std_em - (a.NUMBER_RMPCT+B.NUMBER_EM)) RM_FREE
from COUNT_RMPCT a, COUNT_EM b
where a.bl_id=b.bl_id
and a.fl_id=b.fl_id
and a.rm_id=b.rm_id
if RM_FREE > 0 THEN there are free rooms (D or T) between those occupied in that period.
Now If the room (bl_in,fl_in,rm_in) is free I can reserve inserting it in the table RMPCT:
INSERT INTO rmpct (bl_id, fl_id, rm_id,em_id,cod_stud,date_start, date_end)
values(bl_in,fl_in,rm_in,stud_name,cod_stud,date_start_in,date_end_in);
If I haven't rm_in (can be null) I must reserve the first free room (random).
after these controls: I update table of the students:
UPDATE em
Set bl_id = BL_IN,fl_id= FL_IN,rm_id=rm_in
     where em_id=stud_name
     and cod_stud=cod_stud;
Finally I must make a control on the sex of the room, because there are rooms that have sex=0
if RM.SEX <> 0 then
     null
else
if rm_cat = 'ROOM' then
UPDATE rm
set sex = sex_in
where bl_id = in
and fl_id = in
and rm_id = in;
if rm_cat = 'APARTMENT' then (update on all rooms)
UPDATE rm
set sex = sex_in
where bl_id = in
and fl_id = in;
IF v_appo > 0 then
     Same controls except:      insert into em (em_id,cod_sud,sex)
               values (stud_name,cod_stud,sex_in);
How I can insert in one stored procedure (or package) all these instructions and controls?
Thanks in advance!

Answer 1

In the following demonstation, I have changed the names of some of your variables, in order to standardize them. I have prefaced input parameters with p_ and local variables with v_ and followed them with the name of the column that they are associated with when appropriate. This avoids conflicts with any column names and makes the code easier to read and follow. I have also used table_name.column_name%type to specify the data type associated with the variables instead of using varchar2. That way, if the data type of the columns changes, the code does not have to be updated. This is standard practice.
In your first insert statement, you have attempted to insert sex into the em table, but there is no sex column in the em table data that you displayed, so I removed the sex.
Instead of using a complicated mess of views and such to check whether there is a room available and then assign it, I have used just one select statement to select an available room and used an exception clause that handles a no_data_found exception to deal with when there is no room available.
I have greatly simplified your checking of dates within that select statement.
You were on the right track with the outer joins and grouping and checking for single, double, or triple rooms. Instead of count, I have used sum and nvl2, so that only the occupied rooms are counted and the rows generated by the outer join are zeroes.
I have used the nvl function to allow for null values in the input parameters, so that any room can be selected. I used dbms_random.random to ensure that the rows are ordered randomly, but you can leave that out if it is really not that critical that the result be truly random and any row will do. I have used rownum=1 in an outer query to select just one row.
When you select from a table in pl/sql, you have to select into something. You cannot just issue a select statement, then use an if statement to compare some value in the select statement. For example, you cannot use "if rm.sex ..." you have to select rm.sex into a variable, like v_sex, then use "if v_sex ...". So, I have selected the result of the select statement into local variables, then used those variables for comparisons. I have also used those variables for inserting and updating the appropriate tables, rather than just using the original input parameters, since some of them may have been null.
In the example below, I have demonstrated how the procedure rejects an unavailable room, accepts a specific available room, and randomly assigns a room.
-- procedure:
scott@ORA92> CREATE OR REPLACE PROCEDURE reserve_rooms
  2    -- input parameters:
  3    (p_em_id      IN em.em_id%TYPE,
  4       p_cod_stud   IN em.cod_stud%TYPE,
  5       p_bl_id      IN rm.bl_id%TYPE,
  6       p_fl_id      IN rm.fl_id%TYPE,
  7       p_rm_id      IN rm.rm_id%TYPE,
  8       p_sex          IN rm.sex%TYPE,
  9       p_date_start IN VARCHAR2,
10       p_date_end   IN VARCHAR2)
11  AS
12    -- local variables:
13    v_appo          INTEGER;
14    v_bl_id          rm.bl_id%TYPE;
15    v_fl_id          rm.fl_id%TYPE;
16    v_rm_id          rm.rm_id%TYPE;
17    v_rm_cat      rm.rm_cat%TYPE;
18    v_sex          rm.sex%TYPE;
19  BEGIN
20    -- verify if the student is in table em:
21    SELECT COUNT (*)
22    INTO   v_appo
23    FROM   em
24    WHERE  em_id = p_em_id
25    AND    cod_stud = p_cod_stud;
26    -- if the student is not in table em, then insert new student:
27    IF v_appo = 0 THEN
28        INSERT INTO em (em_id, cod_stud)
29        VALUES (p_em_id, p_cod_stud);
30    END IF;
31    BEGIN
32        -- find available room:
33        SELECT bl_id, fl_id, rm_id, sex, rm_cat
34        INTO     v_bl_id, v_fl_id, v_rm_id, v_sex, v_rm_cat
35        FROM     (SELECT rm.bl_id, rm.fl_id, rm.rm_id, rm.sex, rm.rm_cat
36             FROM     rmpct, rm
37             WHERE     rm.bl_id = rmpct.bl_id (+)
38             AND     rm.fl_id = rmpct.fl_id (+)
39             AND     rm.rm_id = rmpct.rm_id (+)
40             AND     rm.bl_id = NVL (p_bl_id, rm.bl_id)
41             AND     rm.fl_id = NVL (p_fl_id, rm.fl_id)
42             AND     rm.rm_id = NVL (p_rm_id, rm.rm_id)
43             AND     (rm.sex   = p_sex OR rm.sex = 0)
44             AND     rmpct.date_start (+) <= TO_DATE (p_date_end, 'DD-MM-YYYY')
45             AND     rmpct.date_end (+) >= TO_DATE (p_date_start, 'DD-MM-YYYY')
46             GROUP     BY rm.bl_id, rm.fl_id, rm.rm_id, rm.sex, rm.rm_cat, rm.rm_std
47             HAVING SUM (NVL2 (rmpct.rm_id (+), 1, 0))
48                 < DECODE (rm_std, 'S', 1, 'D', 2, 'T', 3)
49             ORDER     BY DBMS_RANDOM.RANDOM)
50        WHERE ROWNUM = 1;
51        -- reserve room:
52        INSERT INTO rmpct (bl_id, fl_id, rm_id, em_id, cod_stud, date_start, date_end)
53        VALUES (v_bl_id, v_fl_id, v_rm_id, p_em_id, p_cod_stud,
54             TO_DATE (p_date_start, 'DD-MM-YYYY'),
55             TO_DATE (p_date_end, 'DD-MM-YYYY'));
56        -- update students:
57        UPDATE em
58        SET     bl_id = v_bl_id, fl_id = v_fl_id, rm_id = v_rm_id
59        WHERE     em_id = p_em_id
60        AND     cod_stud = p_cod_stud;
61        -- update sex of room or apartment floor:
62        IF v_sex = 0 THEN
63          IF v_rm_cat = 'ROOM' THEN
64            UPDATE rm
65            SET    sex = p_sex
66            WHERE  bl_id = v_bl_id
67            AND    fl_id = v_fl_id
68            AND    rm_id = v_rm_id;
69          ELSIF v_rm_cat = 'APARTMENT' THEN
70            UPDATE rm
71            SET    sex = p_sex
72            WHERE  bl_id = v_bl_id
73            AND    fl_id = v_fl_id;
74          END IF;
75        END IF;
76    EXCEPTION
77        -- if no room is available:
78        WHEN NO_DATA_FOUND THEN
79          RAISE_APPLICATION_ERROR (-20001, 'Sorry, there is no such room available.');
80    END;
81  END reserve_rooms;
82  /
Procedure created.
scott@ORA92> SHOW ERRORS
No errors.
-- rejects unavailable room of wrong sex:
scott@ORA92> EXECUTE reserve_rooms ('BARBARA', 654321, 'BL1', 1, 101, 2, '04-02-2005', '10-02-2005')
BEGIN reserve_rooms ('BARBARA', 654321, 'BL1', 1, 101, 2, '04-02-2005', '10-02-2005'); END;
ERROR at line 1:
ORA-20001: Sorry, there is no such room available.
ORA-06512: at "SCOTT.RESERVE_ROOMS", line 79
ORA-06512: at line 1
-- accepts available room of same sex:
scott@ORA92> EXECUTE reserve_rooms ('BARBARA', 654321, 'BL1', 1, 103, 2, '04-02-2005', '10-02-2005')
PL/SQL procedure successfully completed.
-- assigns random available room of same or no sex:
scott@ORA92> EXECUTE reserve_rooms ('BARBARA', 654321, NULL, NULL, NULL, 2, '11-02-2005', '23-02-2005')
PL/SQL procedure successfully completed.
-- results:
scott@ORA92> -- one and only one row added to em table:
scott@ORA92> SELECT * FROM em WHERE em_id = 'BARBARA'
  2  /
EM_ID           BL_I      FL_ID      RM_ID   COD_STUD
BARBARA         BL1           1        102     654321
scott@ORA92> -- rooms reserved and other people who have reserved same room
scott@ORA92> -- (there are 3 who reserved a double room, but only 2 at a time):
scott@ORA92> SELECT *
  2  FROM   rmpct
  3  WHERE  (bl_id, fl_id, rm_id) IN
  4           (SELECT bl_id, fl_id, rm_id
  5            FROM   rmpct
  6            where  em_id = 'BARBARA')
  7  /
EM_ID           BL_      FL_ID      RM_ID DATE_STAR DATE_END    COD_STUD
BARBARA         BL1          1        102 11-FEB-05 23-FEB-05     654321
SERAFINO        BL1          1        102 12-FEB-04 19-FEB-04     589920
VIDAL           BL1          1        102 16-FEB-04 01-MAR-04     602877
SERAFINO        BL1          1        103 01-FEB-04 15-FEB-04     589920
TAKEM           BL1          1        103 04-FEB-05 10-FEB-05     569673
BARBARA         BL1          1        103 04-FEB-05 10-FEB-05     654321
6 rows selected.
scott@ORA92> -- rooms reserved are all correct sex
scott@ORA92> -- (note that room 102 was updated from 0 to 2):
scott@ORA92> SELECT *
  2  FROM   rm
  3  WHERE  (bl_id, fl_id, rm_id) IN
  4           (SELECT bl_id, fl_id, rm_id
  5            FROM   rmpct
  6            where  em_id = 'BARBARA')
  7  /
BL_      FL_ID      RM_ID        SEX R RM_CAT
BL1          1        102          2 D ROOM
BL1          1        103          2 T ROOM
scott@ORA92>