How to determine data distribution in SQL Server columns using T-SQL - sql-server

Question

Can someone show me how to compile code in T-SQL that will allow me to view the distribution of data in columns?
For example in the sample table, there is a column called model. In that column, 50% of the values are Fiestas. I would like to a query that will help determine the distribution of in data in columns.
I have included some sample code to help:
CREATE TABLE #tmpTable
(
registration varchar(50),
make varchar(50),
model varchar(50),
engine_size float
)
INSERT INTO #tmpTable VALUES
('JjFw5a0','SKODA','OCTAVIA',1.8),
('VkfCDpZ','FORD','FIESTA',1.7),
('5E93ZEq','SKODA','OCTAVIA',1.3),
('L2PPN0m','FORD','FIESTA',1.1),
('9xKghxp','FORD','FIESTA',1.5),
('WHShdBm','FORD','FIESTA',1.4),
('TNRHyy7','NISSAN','QASHQAI',1.2),
('6RNX0XG','SKODA','OCTAVIA',1.4),
('tJ9bOD8','FORD','FIESTA',1.1),
('ablFUSC','FORD','FIESTA',1),
('4B7RLYL','MERCEDED_BENZ','E CLASS',1.3),
('tlJiwVY','FORD','FIESTA',1),
('Fb9lcvG','FORD','FIESTA',1.4),
('nW4lqBC','FORD','FIESTA',1.6),
('LggTmL5','HYUNDAI','I20',1),
('2mGgSjS','FORD','FIESTA',1.1),
('IDvOzcM','FORD','FIESTA',1.3),
('JefpXK2','FORD','FIESTA',1.5),
('0h1uWfZ','MERCEDED_BENZ','E CLASS',1.4),
('ylBoGbV','MERCEDED_BENZ','E CLASS',1.7),
('XzoILDK','VAUXHALL','CORSA',1.8),
('Xhocs1Z','FORD','FIESTA',1.5),
('Lh2yWGa','KIA','RIO',1.5),
('hM5GWA0','FORD','FIESTA',1.3),
('PbpxkFt','FORD','FIESTA',1.7),
('SDHWV2r','FORD','FIESTA',1.2),
('n83Je2D','FORD','FIESTA',1.8),
('sDN0gex','FORD','FIESTA',1.2),
('7EICOZY','KIA','RIO',1.5),
('PUuMmIH','FORD','FIESTA',1),
('HiBwSg2','FORD','FIESTA',1.8),
('1yk1vDm','KIA','RIO',1.7),
('cMpH72R','HYUNDAI','I20',1.1),
('ZgQL0gt','MERCEDED_BENZ','E CLASS',1.3),
('jhpamQG','KIA','RIO',1.1),
('pk0lU2F','VAUXHALL','CORSA',1.4),
('fDCUeq1','FORD','FIESTA',1.1),
('ono5QFC','FORD','FIESTA',1.7),
('VohWwGR','FORD','FIESTA',1.5),
('Hih8dKc','SUZUKI','SWIFT',1.2),
('D2RNn3h','SUZUKI','SWIFT',1.2),
('QaYQulE','FORD','FIESTA',1.1),
('xmQPxAG','FORD','FIESTA',1.8),
('vmTqkTO','FORD','FIESTA',1.2),
('lvUtVUA','MERCEDED_BENZ','E CLASS',1),
('SFoj00d','FORD','FIESTA',1),
('9S6wrWV','MERCEDED_BENZ','E CLASS',1),
('0SBnW0z','FORD','FIESTA',1.1),
('HnDHdfj','MERCEDED_BENZ','E CLASS',1),
('RV7q947','FORD','FIESTA',1.4),
('JZqCtTg','FORD','FIESTA',1.7),
('XVgBwgi','FORD','FIESTA',1.8),
('iqJDsIF','FORD','FIESTA',1.6),
('CMbpRFa','FORD','FIESTA',1.6),
('vF7K5Xg','SUZUKI','SWIFT',1.1),
('3j6XGDH','FORD','FIESTA',1.5),
('ommqugM','FORD','FIESTA',1.1),
('LMQkPnw','NISSAN','QASHQAI',1.4),
('1dKgcdd','FORD','FIESTA',1.5),
('hC8BxiP','MERCEDED_BENZ','E CLASS',1.1),
('wLTWol7','FORD','FIESTA',1.6),
('TY8ChYN','FORD','FIESTA',1.6),
('Gw1CpI8','FORD','FIESTA',1.4),
('L4OPAJq','FORD','FIESTA',1.1),
('6TyYpfi','NISSAN','QASHQAI',1.6),
('ozoOcGL','FORD','FIESTA',1.4),
('6IME19U','FORD','FIESTA',1.4),
('BxpmJO5','FORD','FIESTA',1.4),
('0zc2n5A','FORD','FIESTA',1.3),
('FqbBZE2','FIAT','500',1.7),
('2EkTOTz','FORD','FIESTA',1.4),
('fNBvIvg','MERCEDED_BENZ','E CLASS',1.2),
('u5j4R4S','KIA','RIO',1.4),
('zpWaUZo','FORD','FIESTA',1.1),
('FQPVQYc','NISSAN','QASHQAI',1.7),
('8RBQADq','KIA','RIO',1.7),
('TOz2bcT','HYUNDAI','I20',1.7),
('jebhCex','FORD','FIESTA',1.3),
('cdHA1gL','FORD','FIESTA',1.2),
('FoaN4AT','FORD','FIESTA',1.7),
('atGn288','FORD','FIESTA',1.5),
('es8VNdW','FIAT','500',1.3),
('hDWoMXa','KIA','RIO',1.4),
('Q9C6Br1','KIA','RIO',1.5),
('mFSy4aF','FORD','FIESTA',1.6),
('bbbKnrM','SKODA','OCTAVIA',1.5),
('qY7lz6I','FORD','FIESTA',1),
('8Ch2OeU','VAUXHALL','CORSA',1.3),
('dcWsjJv','VAUXHALL','CORSA',1.3),
('bnnoBPg','SKODA','OCTAVIA',1.8),
('mvDyYkK','FORD','FIESTA',1.4),
('KpWDYap','FORD','FIESTA',1.3),
('7EK9K4z','FORD','FIESTA',1.3),
('ZPLHtlP','FORD','FIESTA',1.6),
('4EpYeSB','FORD','FIESTA',1.6),
('O1eZ20M','FORD','FIESTA',1),
('WfVntKk','FORD','FIESTA',1.7),
('6VlkBdi','FORD','FIESTA',1.1),
('hFQfKjk','KIA','RIO',1.4),
('3Y4njNP','KIA','RIO',1),
('3UuNqG0','FORD','FIESTA',1.7),
('qpvMYAu','FORD','FIESTA',1.1),
('NCYJUqx','FORD','FIESTA',1.3),
('M0AvWzg','FORD','FIESTA',1.6),
('XbVmtFf','FORD','FIESTA',1.3),
('l8qZy0H','SKODA','OCTAVIA',1.3),
('EDUbxaU','MERCEDED_BENZ','E CLASS',1.6),
('nWLd82o','FORD','FIESTA',1.7),
('4AkoyWx','FORD','FIESTA',1),
('nOoO25v','FORD','FIESTA',1.3),
('VAm5aV8','NISSAN','QASHQAI',1.4),
('zbd3cie','FORD','FIESTA',1.5),
('hyAN71W','NISSAN','QASHQAI',1),
('FxACHDf','FIAT','500',1.7),
('wOZdaeV','FORD','FIESTA',1.6),
('gfxZl99','VAUXHALL','CORSA',1.1),
('06HhwEJ','SKODA','OCTAVIA',1.7),
('PCTgYiG','KIA','RIO',1.7),
('U54WXZQ','KIA','RIO',1.6),
('FHgrRiF','FORD','FIESTA',1.6),
('R3jP73p','SKODA','OCTAVIA',1.5),
('etVPKX9','SUZUKI','SWIFT',1.1),
('BE3yReB','FORD','FIESTA',1.7),
('zXmX878','FORD','FIESTA',1.6),
('wdM3P2m','FORD','FIESTA',1.7),
('tb727BM','FORD','FIESTA',1.1)
SELECT * FROM #tmpTable

Answer 1

You can apply a Windowed Aggregate to get the overall count:
SELECT make
, model
, count(*) as cnt -- count per Model
, cast(count(*) * 100.0 -- compared to all counts
/ sum(count(*))
over () as dec(5,2)) as distribution
FROM #tmptable
group by make
, model
order by distribution desc;
See fiddle
If you want the percentage of the Model for each Make you need to add PARTITION BY:
SELECT make
, model
, count(*) as cnt -- count per Model
, cast(count(*) * 100.0
/ sum(count(*)) -- compared to all counts per Make
over (partition by Make) as dec(5,2)) as distribution
FROM #tmptable
group by make
, model
order by make, distribution desc;

Answer 2

You can use conditional aggregation to get the ratio of the count of Ford Fiestas and the total count.
SELECT 100.0
* count(CASE
WHEN make = 'FORD'
AND model = 'FIESTA' THEN
1
END)
/ count(*)
FROM #tmptable;
Edit:
If you want the figures for all car models you can simply aggregate and group to get the count for each car model and divide that by the total count which you can get via a subquery.
SELECT make,
model,
100.0
* count(*)
/ (SELECT count(*)
FROM #tmptable)
FROM #tmptable
GROUP BY make,
model;