I have a column in a table with values of 1 given to users who purchase a trial, and 0 given to users who do not.
I want the total of users who have purchased the trial. The unique identifier in the table is given by user_id.
Will the IF operator work? Can anyone explain why or why not?
You would just do:
select count(*) from users where trial=1
or
select sum(trial) from users
Why are you thinking to use IF?
You can use the query:
SELECT COUNT(*) FROM TABLE_NAME WHERE TRIAL=1
Or you can just specify the condition in COUNT() function itself like
select count(case trial when 1 then 1 else null end) from users
Using a SUM() function like
select sum(case when trial = 1 then 1 else 0 end) from users
Related
I'm calculating the total user who deposit on today.
I'm counting the total number row of user that deposited on today and group by user.
I will get an error:
Trying to access array offset on value of type null
When it's 00:00 hrs as it's new day and no user deposit yet.
I need help on how to return 0 if there is no row returned?
I used ISNULL() and COALESCE() but it does not work.
I used d_status as an indicator of successful deposit.
SELECT COALESCE(COUNT(user_id),0) as total_activeuser
FROM deposit
WHERE d_status = 1
GROUP BY user_id;
First, there is no need for coalesce():
SELECT COUNT(*) as total_activeuser
FROM deposit
WHERE d_status = 1
GROUP BY user_id;
The problem is that only users with d_status = 1 are in the result set. If you want all of them, then one method is to use conditional aggregation:
SELECT SUM(CASE WHEN d_status = 1 THEN 1 ELSE 0 END) as total_activeuser
FROM deposit
GROUP BY user_id;
If you want the total number of users that match the condition, then perhaps:
select count(distinct user_id)
from deposit
where d_status = 1;
I’m trying to use a correlated subquery in my sql code and I can't wrap my head around what I'm doing wrong. A brief description about the code and what I'm trying to do:
The code consists of a big query (ALIASED AS A) which result set looks like a list of customer IDs, offer IDs and response status name ("SOLD","SELLING","IRRELEVANT","NO ANSWER" etc.) of each customer to each offer. The customers IDs and the responses in the result set are non-unique, since more than one offer can be made to each customer, and a customer can have different response for different offers.
The goal is to generate a list of distinct customer IDs and to mark each ID with 0 or 1 flag :
if the ID has AT LEAST ONE offer with status name is "SOLD" or "SELLING" the flag should be 1 otherwise 0. Since each customer has an array of different responses, what I'm trying to do is to check if "SOLD" or "SELLING" appears in this array for each customer ID, using correlated subquery in the case statement and aliasing the big underlying query named A with A1 this time:
select distinct
A.customer_ID,
case when 'SOLD' in (select distinct A1.response from A as A1
where A.customer_ID = A1.customer_ID) OR
'SELLING' in (select distinct A1.response from A as A1
where A.customer_ID = A1.customer_ID)
then 1 else 0 end as FLAG
FROM
(select …) A
What I get is a mistake alert saying there is no such object as A or A1.
Thanks in advance for the help!
You can use exists with cte :
with cte as (
<query here>
)
select c.*,
(case when exists (select 1
from cte c1
where c1.customer_ID = c.customer_ID and
c1.response in ('sold', 'selling')
)
then 1 else 0
end) as flag
from cte c;
You can also do aggregation :
select customer_id,
max(case when a.response in ('sold', 'selling') then 1 else 0 end) as flag
from < query here > a;
group by customer_id;
With statement as suggested by Yogesh is a good option. If you have any performance issues with "WITH" statement. you can create a volatile table and use columns from volatile table in your select statement .
create voltaile table as (select response from where response in ('SOLD','SELLING').
SELECT from customer table < and join voltaile table>.
The only disadvantge here is volatile tables cannot be accessed after you disconnect from session.
I have some sales data that shows if a bill has been generated for a customer. The column labelled bill_generated returns 'Y' if a bill has been generated else its blank. I am trying to find the list of customers for whom atleast one bill has been generated. There could be multiple rows for each cust_id as shown below:
cust_id, bill_generated
001,NULL
001,Y
002,NULL
002,NULL
003,Y
Could anyone advice on this. I am using Redshift DB. Thanks..
Try below using group by and having cluse
select cust_id from tablename
group by cust_id
having sum(case when bill_generated is null then 0 else 1 end)=1
you can use co-related sub-query
select * from t
where exists (select 1 from t t1
where t1.bill_generated='Y' and t1.cust_id=t.cust_id
)
I am looking to order a list of keys based on the number of orders placed from a database containing order requests. Basically, on table, call it orders(o_partkey, o_returnflag) I am trying to get the total number of returns for each order. I have tried many variations of the following snippet with the goal schema returnlist(partkey, numreturns):
select O.o_partkey as partkey,
count(case when O.o_returnflag = 'R' then 1 else 0 end) as numreturns
from orders O
orderby quantity_returned desc;
I am very new to SQLite and am just jumping into the basics. This is an adjustment of a homework question (the actual question is more complex) but I have simplified down the issue I am having.
Consider using a derived table subquery with SUM() as the aggregate function:
SELECT dT.partkey, dT.numreturns
FROM
(SELECT O.o_partkey as partkey,
SUM(CASE WHEN O.o_returnflag = 'R' THEN 1 ELSE 0 END) as numreturns
FROM [ORDER] O
GROUP BY O.o_partkey) AS dT
ORDER BY dT.numreturns DESC;
Be sure to bracket name of table as [ORDER] is an SQLite key word.
Your problem is that COUNT counts rows, so it counts both 0 and 1 values.
You are not interested in any other rows, so you can just filter out the returns with WHERE:
SELECT o_partkey AS partkey,
COUNT(*) AS numreturns
FROM orders
WHERE o_returnflag = 'R'
ORDER BY 2 DESC;
I have table called stats. In am inserting yes or no in the table, and I want to show the number of yes count and the number of no count.
Can somebody please help me with the query?
select yn, count(*)
from stats
group by yn;
Try something like this
SELECT SUM(CASE WHEN recommend = 'Y' THEN 1 ELSE 0 END) YesCount,
SUM(CASE WHEN recommend = 'N' THEN 1 ELSE 0 END) NoCount,
COUNT(*) TotalCount
FROM Stats
This is exactly what the GROUP BY clause and aggregate functions are for in SQL. The following should be what you need and more efficient then a CASE statement. It returns a table with two columns: recommend and no (which is the count of identical values in the recommend column. If what you said above is true, then this should return at most two rows.
SELECT recommend, count(*) AS no FROM stats GROUP BY recommend