select from table where a=1 and a=2 - sql

Question

i have a four requirement (may be four select is ok) where I need to find from single table, if customer has
a. apple and samsung
b. no_apple and no_samsung
c. apple and no_samsung
d. no_apple and samsung
my table be like...
cust_name device
john apple
john samsung
dave apple
tim samsung
patrick nokia
rick nokia
so expect output be like...
a:- output ( both apple and samsung)
count(*)
1
b:-output (no_apple and no_samsung)
count(*)
2
c:-output (apple and no_samsung)
count(*)
1
d:-output (no_apple and samsung)
count(*)
1

Answer 1

You can do it all in a single query using conditional aggregation:
SELECT COUNT(CASE WHEN num_apple > 0 AND num_samsung > 0 THEN 1 END)
AS apple_and_samsung,
COUNT(CASE WHEN num_apple = 0 AND num_samsung > 0 THEN 1 END)
AS no_apple_and_samsung,
COUNT(CASE WHEN num_apple > 0 AND num_samsung = 0 THEN 1 END)
AS apple_and_no_samsung,
COUNT(CASE WHEN num_apple = 0 AND num_samsung = 0 THEN 1 END)
AS no_apple_and_no_samsung
FROM (
SELECT cust_name,
COUNT(CASE device WHEN 'apple' THEN 1 END) AS num_apple,
COUNT(CASE device WHEN 'samsung' THEN 1 END) AS num_samsung
FROM table_name
GROUP BY cust_name
)
Which, for the sample data:
CREATE TABLE table_name (cust_name, device) AS
SELECT 'john', 'apple' FROM DUAL UNION ALL
SELECT 'john', 'samsung' FROM DUAL UNION ALL
SELECT 'dave', 'apple' FROM DUAL UNION ALL
SELECT 'tim', 'samsung' FROM DUAL UNION ALL
SELECT 'patrick', 'nokia' FROM DUAL UNION ALL
SELECT 'rick', 'nokia' FROM DUAL;
Outputs:
APPLE_AND_SAMSUNG
NO_APPLE_AND_SAMSUNG
APPLE_AND_NO_SAMSUNG
NO_APPLE_AND_NO_SAMSUNG
1
1
1
2
You can also do it by PIVOTing twice:
SELECT *
FROM table_name
PIVOT (
COUNT(DISTINCT device) FOR device IN (
'apple' AS apple,
'samsung' AS samsung
)
)
PIVOT (
COUNT(cust_name) FOR (apple, samsung) IN (
(1, 1) AS apple_and_samsung,
(1, 0) AS apple_and_no_samsung,
(0, 1) AS no_apple_and_samsung,
(0, 0) AS no_apple_and_no_samsung
)
)
db<>fiddle here

Answer 2

You might add proper HAVING clauses for each case after GROUPing by cust_name column such as
a)
SELECT COUNT(DISTINCT cust_name)
FROM t
GROUP BY cust_name
HAVING SUM(CASE WHEN device ='apple' THEN 1 ELSE 0 END)
* SUM(CASE WHEN device ='samsung' THEN 1 ELSE 0 END) = 1;
b)
SELECT SUM(COUNT(DISTINCT cust_name))
FROM t
GROUP BY cust_name
HAVING MIN(CASE WHEN device ='apple' THEN 0 ELSE 1 END)
* MIN(CASE WHEN device ='samsung' THEN 0 ELSE 1 END) = 1;
c)
SELECT COUNT(DISTINCT cust_name)
FROM t
GROUP BY cust_name
HAVING MIN(CASE WHEN device ='samsung' THEN 0 ELSE 1 END)
* MIN(CASE WHEN device ='apple' THEN 1 ELSE 0 END) = 1;
d)
SELECT COUNT(DISTINCT cust_name)
FROM t
GROUP BY cust_name
HAVING MIN(CASE WHEN device ='apple' THEN 0 ELSE 1 END)
* MIN(CASE WHEN device ='samsung' THEN 1 ELSE 0 END) = 1
Demo