SQL - combined SELECT queries and getting a % output - sql

Question

I am using SQLiteStudio and I am trying to run the following query. However, it isn't returning a value. Can anyone help, please?
SELECT
(SELECT COUNT(t_record.LocationID)
FROM t_record,
t_location
WHERE t_record.LocationID = t_location.LocationID AND
Y_AXIS >= 0 AND
Goal_for = 1)
/
(SELECT COUNT(GoalID)
FROM t_record
WHERE t_record.Goal_for)
* 100
I have been asked to provide some of the data. Below I have included how I created my 3 tables and then some sample data for each section. Hopefully, this is enough but feel free to ask for more.
These are the 3 tables I have created
CREATE TABLE t_location (
LocationID INT PRIMARY KEY,
X_Axis INT NOT NULL,
Y_AXIS INT NOT NULL
);
CREATE TABLE t_method (
MethodID INT PRIMARY KEY,
Body_Part VARCHAR(45) NOT NULL
);
CREATE TABLE t_record (
GoalID INT PRIMARY KEY,
LocationID [INT FORIEIGN KEY] REFERENCES t_location (LocationID),
MethodID [INT FORIEIGN KEY] REFERENCES t_method (MethodID),
Time INT NOT NULL,
Goal_for BOOLEAN NOT NULL
Data for the method table
INSERT INTO t_method
VALUES (1,'Left Foot');
INSERT INTO t_method
VALUES (2,'Right Foot');
INSERT INTO t_method
VALUES (3,'Head');
Data for the location table - only included 3 locations.
INSERT INTO t_location
VALUES (1, 0, -1);
INSERT INTO t_location
VALUES (2, 0, 0);
INSERT INTO t_location
VALUES (3, 0, 1);
Data for the record table, it is very pland but I've varied the location.
INSERT INTO t_record
VALUES (1, 1, 1, 28, 1);
INSERT INTO t_record
VALUES (2, 1, 1, 6, 1);
INSERT INTO t_record
VALUES (3, 2, 1, 28, 1);
INSERT INTO t_record
VALUES (4, 2, 1, 28, 1);
INSERT INTO t_record
VALUES (5, 2, 1, 28, 1);
INSERT INTO t_record
VALUES (6, 2, 1, 28, 1);
INSERT INTO t_record
VALUES (7, 3, 1, 28, 1);
INSERT INTO t_record
VALUES (8, 3, 1, 28, 1);
INSERT INTO t_record
VALUES (9, 3, 1, 28, 1);
INSERT INTO t_record
VALUES (10, 3, 1, 28, 1);
INSERT INTO t_record
VALUES (11, 3, 1, 28, 1);
INSERT INTO t_record
VALUES (12, 3, 1, 28, 1);
INSERT INTO t_record
VALUES (1, 3, 1, 28, 1);
Thanks

Answer 1

Actually you had just a few syntax errors and correcting them plus adding something like * 1.0 to count() would do what you want (otherwise count() results are integer and in SQL server integer / integer would yield an integer which is 0 in your case).
This is your code, slightly modified to work:
SELECT
(SELECT COUNT(t_record.LocationID)
FROM t_record,
t_location
WHERE t_record.LocationID = t_location.LocationID AND
Y_AXIS >= 0 AND
Goal_for = 1) * 1.0
/
(SELECT COUNT(GoalID)
FROM t_record
WHERE t_record.Goal_for=1)
* 100;
(I agree with preventing old style joins etc but was not the problem here).
You could make it a little better:
SELECT
(SELECT COUNT(t_record.LocationID)
FROM t_record,
t_location
WHERE t_record.LocationID = t_location.LocationID AND
Y_AXIS >= 0 AND
Goal_for = 1) * 100.0
/
(SELECT COUNT(GoalID)
FROM t_record
WHERE t_record.Goal_for=1) as Pct;
While the above code works, I think there is a better and cleaner way:
SELECT SUM(case when Y_AXIS >= 0 then 1 end) * 100.0 / COUNT(*)
FROM t_record
inner join t_location ON t_record.LocationID = t_location.LocationID
where Goal_for = 1;
You can also check what is really going on there with adding those fields:
SELECT
SUM(case when Y_AXIS >= 0 then 1 end) as YAXIS_GTE_ZERO,
COUNT(*) as Total,
SUM(case when Y_AXIS >= 0 then 1 end) * 100.0 / COUNT(*) as Pct
FROM t_record
inner join t_location ON t_record.LocationID = t_location.LocationID
where Goal_for = 1;
And here is DBFiddle demo using your example data
EDIT: And this is for YAXIS >= 0 and YAXIS < 0 as in your comment:
SELECT
SUM(CASE WHEN Y_AXIS>=0 THEN 1 END) AS Opp_half_goals
, SUM(CASE WHEN Y_AXIS<0 THEN 1 END) AS Own_half_goals
, COUNT(*) AS Total
, SUM(CASE WHEN Y_AXIS>=0 THEN 1 END)* 100.0 / COUNT(*) AS Opp_half_Pct
, SUM(CASE WHEN Y_AXIS<0 THEN 1 END) * 100.0 / COUNT(*) AS Own_half_Pct
FROM t_record
INNER JOIN t_location ON t_record.LocationID=t_location.LocationID
WHERE Goal_for=1;

Answer 2

I Tried this; using 1.0 instead of 1 in the CASE WHEN expression, to avoid an integer division by integer, which would have resulted in a truncated integer as the result, namely 0:
SELECT
SUM(CASE WHEN y_axis >= 0 THEN 1.0 END)
/ COUNT(*)
* 100
AS result
FROM t_record
JOIN t_location USING(locationid)
;
-- out result
-- out ------------------------
-- out 84.6153846153846153800