/** Grocery list: Bananas (4)Peanut Butter (1)Dark Chocolate Bars (2)**/CREATE TABLE groceries (id INTEGER PRIMARY KEY, name TEXT, quantity INTEGER );INSERT INTO groceries VALUES (1, "Bananas", 4);INSERT INTO groceries VALUES (2, "Peanut Butter", 1);INSERT INTO groceries VALUES (3, "Dark chocolate bars", 2);SELECT * FROM groceries;
This database contains an incomplete list of box office hits and their release year. In this challenge, you're going to get the results back out of the database in different ways! In this first step, just select all the movies.
Now, add a second query after the first, that retrieves only the movies that were released in the year 2000 or later, not before. Sort the results so that the earlier movies are listed first. You should have 2 SELECT statements after this step.
CREATE TABLE movies (id INTEGER PRIMARY KEY, name TEXT, release_year INTEGER);INSERT INTO movies VALUES (1, "Avatar", 2009);INSERT INTO movies VALUES (2, "Titanic", 1997);INSERT INTO movies VALUES (3, "Star Wars: Episode IV - A New Hope", 1977);INSERT INTO movies VALUES (4, "Shrek 2", 2004);INSERT INTO movies VALUES (5, "The Lion King", 1994);INSERT INTO movies VALUES (6, "Disney's Up", 2009); SELECT * FROM movies;SELECT * FROM movies WHERE release_year >= 2000 ORDER BY release_year;
The default sequence is ASC(ascending)order, so from small at the top to large at the bottom.
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Aggregating date
CREATE TABLE groceries (id INTEGER PRIMARY KEY, name TEXT, quantity INTEGER, aisle INTEGER);INSERT INTO groceries VALUES (1, "Bananas", 56, 7);INSERT INTO groceries VALUES(2, "Peanut Butter", 1, 2);INSERT INTO groceries VALUES(3, "Dark Chocolate Bars", 2, 2);INSERT INTO groceries VALUES(4, "Ice cream", 1, 12);INSERT INTO groceries VALUES(5, "Cherries", 6, 2);INSERT INTO groceries VALUES(6, "Chocolate syrup", 1, 4);SELECT aisle, SUM(quantity) FROM groceries GROUP BY aisle;
GROUP BY表示从aisle挑选出元素进行汇总
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More complex queries with AND/OR
CREATE TABLE exercise_logs (id INTEGER PRIMARY KEY AUTOINCREMENT, /*id 序号自动增加*/ type TEXT, minutes INTEGER, calories INTEGER, heart_rate INTEGER);INSERT INTO exercise_logs(type, minutes, calories, heart_rate) VALUES ("biking", 30, 100, 110); /*重新声明，只填需要填充的元素名称*/INSERT INTO exercise_logs(type, minutes, calories, heart_rate) VALUES ("biking", 10, 30, 105);INSERT INTO exercise_logs(type, minutes, calories, heart_rate) VALUES ("dancing", 15, 200, 120);SELECT * FROM exercise_logs WHERE calories > 50 ORDER BY calories;/* AND */SELECT * FROM exercise_logs WHERE calories > 50 AND minutes < 30;/* OR */SELECT * FROM exercise_logs WHERE calories > 50 OR heart_rate > 100;