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RSS订阅原创 Using Null------sqlzoo个人笔记
1.List the teachers who have NULL for their department. select teacher.name from teacher left join dept on teacher.dept = dept.id where dept is null 2.Note the INNER JOIN misses the teachers with no department and the departments with no teacher. select t
2020-12-16 10:06:34
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原创 More JOIN operations------sqlzoo个人笔记
1.List the films where the yr is 1962 [Show id, title] More JOIN operations 2.Give year of ‘Citizen Kane’. select yr from movie where title = 'Citizen Kane' 3.List all of the Star Trek movies, include the id, title and yr (all of these movies include th.
2020-12-06 22:01:20
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原创 The JOIN operation------sqlzoo个人笔记
4.Show the team1, team2 and player for every goal scored by a player called Mario player LIKE ‘Mario%’ select team1 ,team2 ,player from game join goal on game.id=goal.matchid where goal.player like 'Mario%' 6.List the dates of the matches and the name of.
2020-12-06 11:04:04
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原创 SUM and COUNT------sqlzoo个人笔记
SUM and COUNT------sqlzoo个人笔记 1.Show the total population of the world. select sum(population) from world 2.List all the continents - just once each. select distinct continent from world 3.Give the total GDP of Africa select sum(GDP) from world where con
2020-12-03 21:48:08
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