sql finding cid with most expired cards [closed] - sql

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I have a table Cards(card_id,status,cid)
With the columns:
cid - customer id
status - exp/vld
card_id - card id's
How to find the cid with the most expired cards?

Answer 1

From Oracle 12, you can use:
SELECT cid,
COUNT(*) AS num_exp
FROM cards
WHERE status = 'exp'
GROUP BY cid
ORDER BY num_exp DESC
FETCH FIRST ROW WITH TIES;

Answer 2

You can get count of expired cards for individual customers and then choose customer with MAX count. The below query should give results.
WITH t AS(
SELECT cid, count(1) customer_exp_cards_count
FROM Cards where status = 'exp'
group by cid)
SELECT cid FROM t t1
WHERE t1.customer_exp_cards_count IN (SELECT MAX(t2.customer_exp_cards_count)
FROM t t2)
Sample data and its result:
cardid status cid
3 exp 5
1 exp 1
2 exp 1
3 vld 1
5 vld 1
1 exp 2
2 exp 2
3 exp 2
4 vld 2
5 vld 2
6 exp 3
7 vld 4
4 vld 5
Result:
2

Answer 3

Suppose you have these two tables (just a sample data)
CUSTOMERS
CUST_ID
CUST_NAME
CUST_STATUS
101
John
ACTIVE
102
Annie
ACTIVE
103
Jane
ACTIVE
104
Bob
INACTIVE
CARDS
CARD_ID
CARD_STATUS
CUST_ID
1001001
VALID
101
1001002
VALID
101
1001003
EXPIRED
101
1001004
EXPIRED
101
1001005
VALID
101
1002010
VALID
102
1002020
EXPIRED
102
1002030
EXPIRED
102
1002040
EXPIRED
102
1003100
VALID
103
1003200
VALID
103
If you want just a CUST_ID with the number of most expired cards you can do it without table CUSTOMERS:
Select CUST_ID, EXPIRED_CARDS
From (Select CUST_ID, Count(CARD_ID) "EXPIRED_CARDS" From cards Where CARD_STATUS = 'EXPIRED' Group By CUST_ID)
Where EXPIRED_CARDS = (Select Max(EXPIRED_CARDS) From (Select Count(CARD_ID) "EXPIRED_CARDS" From cards Where CARD_STATUS = 'EXPIRED' Group By CUST_ID) )
--
-- R e s u l t
-- CUST_ID EXPIRED_CARDS
-- ---------- -------------
-- 102 3
Maybe you could consider creating a CTE with the data from both tables which will give you dataset that you could use later for different questions not just for this one. Something like this:
WITH
customers_cards AS
(
Select
cst.CUST_ID,
cst.CUST_NAME,
cst.CUST_STATUS,
crd.CARD_ID,
crd.CARD_STATUS,
Sum(CASE WHEN crd.CUST_ID Is Null Then 0 Else 1 End) OVER(Partition By crd.CUST_ID) "TOTAL_NUM_OF_CARDS",
Sum(CASE WHEN crd.CARD_ID Is Null Then Null WHEN crd.CARD_STATUS = 'VALID' And crd.CARD_ID Is Not Null Then 1 Else 0 End) OVER(Partition By crd.CUST_ID) "VALID_CARDS",
Sum(CASE WHEN crd.CARD_ID Is Null Then Null WHEN crd.CARD_STATUS = 'EXPIRED' And crd.CARD_ID Is Not Null Then 1 Else 0 End) OVER(Partition By crd.CUST_ID) "EXPIRED_CARDS"
From
customers cst
Left Join
cards crd on(crd.CUST_ID = cst.CUST_ID)
)
/* R e s u l t :
CUST_ID CUST_NAME CUST_STATUS CARD_ID CARD_STATUS TOTAL_NUM_OF_CARDS VALID_CARDS EXPIRED_CARDS
---------- --------- ----------- ------- ----------- ------------------ ----------- -------------
101 John ACTIVE 1001001 VALID 5 3 2
101 John ACTIVE 1001002 VALID 5 3 2
101 John ACTIVE 1001003 EXPIRED 5 3 2
101 John ACTIVE 1001004 EXPIRED 5 3 2
101 John ACTIVE 1001005 VALID 5 3 2
102 Annie ACTIVE 1002010 VALID 4 1 3
102 Annie ACTIVE 1002040 EXPIRED 4 1 3
102 Annie ACTIVE 1002030 EXPIRED 4 1 3
102 Annie ACTIVE 1002020 EXPIRED 4 1 3
103 Jane ACTIVE 1003100 VALID 2 2 0
103 Jane ACTIVE 1003200 VALID 2 2 0
104 Bob INACTIVE 0
*/
This can be used to answer many more potential questions. Here is the list of customers sorted by number of expired cards (descending):
Select Distinct
CUST_ID, CUST_NAME, TOTAL_NUM_OF_CARDS, VALID_CARDS, EXPIRED_CARDS
From
customers_cards
Order By
EXPIRED_CARDS Desc Nulls Last, CUST_ID
--
-- R e s u l t :
-- CUST_ID CUST_NAME TOTAL_NUM_OF_CARDS VALID_CARDS EXPIRED_CARDS
-- ---------- --------- ------------------ ----------- -------------
-- 102 Annie 4 1 3
-- 101 John 5 3 2
-- 103 Jane 2 2 0
-- 104 Bob 0
OR to answer your question:
Select Distinct
CUST_ID, CUST_NAME, TOTAL_NUM_OF_CARDS, VALID_CARDS, EXPIRED_CARDS
From
customers_cards
Where
EXPIRED_CARDS = (Select Max(EXPIRED_CARDS) From customers_cards)
Order By
CUST_ID
--
-- R e s u l t :
-- CUST_ID CUST_NAME TOTAL_NUM_OF_CARDS VALID_CARDS EXPIRED_CARDS
-- ---------- --------- ------------------ ----------- -------------
-- 102 Annie 4 1 3
Regards...