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@ -54,6 +54,7 @@ SELECT * FROM employees ORDER BY age ASC LIMIT 2;
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SELECT * FROM employees ORDER BY age ASC LIMIT 2 OFFSET 1;
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SELECT * FROM employees ORDER BY age DESC, NAME ASC;
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-- ALTER TABLE
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ALTER TABLE employees ADD COLUMN weight FLOAT;
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ALTER TABLE employees DROP COLUMN height;
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ALTER TABLE employees ADD COLUMN height FLOAT AFTER NAME;
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@ -63,6 +64,7 @@ ALTER TABLE employees ADD COLUMN dob DATETIME;
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ALTER TABLE employees CHANGE dob date_of_birth DATETIME;
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ALTER TABLE companies ADD COLUMN id INT NOT NULL AUTO_INCREMENT PRIMARY KEY FIRST;
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-- AGGREGATION
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SELECT COUNT(*), age FROM employees GROUP BY age;
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SELECT COUNT(*) FROM employees GROUP BY age;
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SELECT SUM(age) FROM employees GROUP BY age;
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@ -72,6 +74,7 @@ SELECT MAX(age) FROM employees;
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SELECT GROUP_CONCAT(age) FROM employees;
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SELECT GROUP_CONCAT(age) FROM employees, name;
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-- JOINS
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SELECT * from employees FULL JOIN companies;
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SELECT * FROM employees JOIN companies ON employees.`employer_id` = companies.`id`;
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SELECT * FROM employees RIGHT OUTER JOIN companies ON employees.`employer_id` = companies.id WHERE employees.`employer_id` IS NULL;
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