56 lines
2.2 KiB
MySQL
56 lines
2.2 KiB
MySQL
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-- GROUP BY group_expression [ , group_expression [ , ... ] ] [ WITH { ROLLUP | CUBE } ]
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-- GROUP BY { group_expression | { ROLLUP | CUBE | GROUPING SETS } (grouping_set [ , ...]) } [ , ... ]
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-- aggregate_name ( [ DISTINCT ] expression [ , ... ] ) [ FILTER ( WHERE boolean_expression ) ]
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-- Sum of quantity per dealership. Group by `id`.
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SELECT id, sum(quantity) FROM dealer GROUP BY id ORDER BY id;
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-- Use column position in GROUP by clause.
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SELECT id, sum(quantity) FROM dealer GROUP BY 1 ORDER BY 1;
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-- Multiple aggregations.
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-- 1. Sum of quantity per dealership.
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-- 2. Max quantity per dealership.
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SELECT id, sum(quantity) AS sum, max(quantity) AS max FROM dealer GROUP BY id ORDER BY id;
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-- Count the number of distinct dealer cities per car_model.
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SELECT car_model, count(DISTINCT city) AS count FROM dealer GROUP BY car_model;
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-- Sum of only 'Honda Civic' and 'Honda CRV' quantities per dealership.
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SELECT id, sum(quantity) FILTER (
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WHERE car_model IN ('Honda Civic', 'Honda CRV')
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) AS `sum(quantity)` FROM dealer
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GROUP BY id ORDER BY id;
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-- Aggregations using multiple sets of grouping columns in a single statement.
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-- Following performs aggregations based on four sets of grouping columns.
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-- 1. city, car_model
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-- 2. city
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-- 3. car_model
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-- 4. Empty grouping set. Returns quantities for all city and car models.
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SELECT city, car_model, sum(quantity) AS sum FROM dealer
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GROUP BY GROUPING SETS ((city, car_model), (city), (car_model), ())
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ORDER BY city;
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-- Group by processing with `ROLLUP` clause.
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-- Equivalent GROUP BY GROUPING SETS ((city, car_model), (city), ())
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SELECT city, car_model, sum(quantity) AS sum FROM dealer
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GROUP BY city, car_model WITH ROLLUP
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ORDER BY city, car_model;
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-- Group by processing with `CUBE` clause.
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-- Equivalent GROUP BY GROUPING SETS ((city, car_model), (city), (car_model), ())
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SELECT city, car_model, sum(quantity) AS sum FROM dealer
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GROUP BY city, car_model WITH CUBE
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ORDER BY city, car_model;
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--Select the first row in column age
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SELECT FIRST(age) FROM person;
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--Get the first row in column `age` ignore nulls,last row in column `id` and sum of column `id`.
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SELECT FIRST(age IGNORE NULLS), LAST(id), SUM(id) FROM person;
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