Hi All,
How can i write a query to count the number of records from a derived table. the derived table is a union of two table.
select msisdn from enrollOffer union DISTINCT select msisdn from enrollHistory
Hi All,
How can i write a query to count the number of records from a derived table. the derived table is a union of two table.
select msisdn from enrollOffer union DISTINCT select msisdn from enrollHistory
SELECT COUNT(*)
FROM
(SELECT
msisdn
FROM enrollOffer
UNION
SELECT
msisdn
FROM enrollHistory
)
If you want to count msisdn that are present in both tables as well, use UNION ALL.
I tried this and am getting the error
ERROR 1248 (42000): Every derived table must have its own alias
SELECT COUNT(*)
FROM
(SELECT
msisdn
FROM enrollOffer
UNION
SELECT
msisdn
FROM enrollHistory
) AS a
Ah yes, forgot the alias
I have tried to put the alian as
SELECT COUNT(cout) FROM (SELECT msisdn as cout FROM enrollOffer UNION SELECT msisdn as cout FROM enrollHistory );
but it is all failing. same error message
have a look at exactly where guido put the alias – compare post #2 and post #4