Oracle - Sum function and flag column update - oracle

Question

CREATE TABLE TABLE2_LINES (NAMES VARCHAR2(12), LINE_NO NUMBER, UNITS NUMBER(18,4), CODE VARCHAR2(4));
INSERT INTO TABLE2_LINES VALUES ('JOHN',1,1,'101');
INSERT INTO TABLE2_LINES VALUES ('JOHN',2,1,'202');
INSERT INTO TABLE2_LINES VALUES ('JOHN',3,1,'180');
INSERT INTO TABLE2_LINES VALUES ('JOHN',4,2,'300');
INSERT INTO TABLE2_LINES VALUES ('RYAN',1,2,'180');
INSERT INTO TABLE2_LINES VALUES ('RYAN',2,1,'180');
INSERT INTO TABLE2_LINES VALUES ('RYAN',3,1,'500');
INSERT INTO TABLE2_LINES VALUES ('OLAN',1,1,'301');
INSERT INTO TABLE2_LINES VALUES ('TONY',1,1,'201');
COMMIT;
CREATE TABLE TABLE4_CODES (CD_NM VARCHAR2(12), B_CODE VARCHAR2(4), E_CODE VARCHAR2(4));
INSERT INTO TABLE4_CODES VALUES ('CODELIST','100','101');
INSERT INTO TABLE4_CODES VALUES ('CODELIST','180','180');
INSERT INTO TABLE4_CODES VALUES ('CODELIST','200','219');
INSERT INTO TABLE4_CODES VALUES ('EXCODELIST','180','180');
COMMIT;
CREATE TABLE RESULT1 (NAMES VARCHAR2(12), TOT_UNITS NUMBER, FLAG VARCHAR2(2));
COMMIT;
Case 1: For person JOHN, We have eligible codes i.e. 101,202,180 (these codes present in TABLE4_CODES table of CD_NM CODELIST). It has other eligible codes along with 180 so SUM(UNITS) is 3 and FLAG should be populated as O
Case 2: For person RYAN, We have only 1 eligible code i.e. 180 only (this code present in TABLE4_CODES table of CD_NM EXCODELIST...Need to look into CD_NM = EXCODELIST instead of CODELIST), so SUM(UNITS) is 3 and FLAG should be populated as N
Case 3: For person OLAN, we don't have eligible codes so need to do anything.
Case 4: For person TONY, we have eligible code 201 but we don't have 180 so (this code present in TABLE4_CODES table of CD_NM = CODELIST), so SUM(UNITS) is 1 and FLAG should be populated as N
If particular person has multiple eligible codes along with 180, we need to look into TABLE4_CODES table of CD_NM CODELIST before proceeding for sum calculation. Ex: JOHN
If particular person has single/multiple eligible codes with don't have 180, we need to look into TABLE4_CODES table of CD_NM CODELIST before proceeding for sum calculation Ex: TONY
If particular person has only 1 eligible code i.e. 180, we need to look into TABLE4_CODES table of CD_NM EXCODELIST before proceeding for sum calculation. Ex: RYAN
Output to be expected in RESULT1 table using TABLE2_LINES and TABLE4_CODES:
NAMES TOT_UNITS FLAG
-----------------------------
JOHN 3 O
RYAN 3 N
TONY 1 O

Answer 1

This is how I understood it. Read comments within code.
SQL> with
2 t180 as
3 -- does NAME have code = 180? If so, return 1; else, return 0
4 (select t2.names,
5 max(case when t2.code = 180 then 1 else 0 end) as f180
6 from table2_lines t2
7 group by t2.names
8 ),
9 eligible as
10 -- number of eligible rows per NAME
11 (select t2.names,
12 count(distinct t2.code) cnt_eligible
13 from table2_lines t2 join table4_codes t4 on t2.code
14 between t4.b_code and t4.e_code
15 group by t2.names
16 ),
17 total_rows as
18 -- gotal number of rows per NAME
19 (select t2.names,
20 count(*) cnt_total
21 from table2_lines t2
22 group by t2.names
23 )
24 -- apply rules (within the CASE expression) to return desired result
25 select distinct
26 t2.names,
27 case when e.cnt_eligible = 1 and f.f180 = 1 then t.cnt_total -- Ryan, N
28 when e.cnt_eligible >= 1 and f.f180 = 0 then e.cnt_eligible -- Tony, O
29 when e.cnt_eligible >= 1 and f.f180 = 1 then e.cnt_eligible -- John, O
30 end tot_units,
31 --
32 case when e.cnt_eligible = 1 and f.f180 = 1 then 'N' -- Ryan, N
33 when e.cnt_eligible >= 1 and f.f180 = 0 then 'O' -- Tony, O
34 when e.cnt_eligible >= 1 and f.f180 = 1 then 'O' -- John, O
35 end flag
36 from table2_lines t2 join t180 f on f.names = t2.names
37 join eligible e on e.names = t2.names
38 join total_rows t on t.names = t2.names;
Result:
NAMES TOT_UNITS FLAG
------------ ---------- ----
JOHN 3 O
RYAN 3 N
TONY 1 O
SQL>