SQL Distinct
Distinct is a keyword used with SELECT to return only unique values. Usually, you want to get all unique values, but there are duplicate values stored in the tables.
Check the difference: in our table, there are 18 records at all, and each record has a singer. You'll retrieve the 18 singers with the next query:
12SELECT singer FROM songs
But some singers, for example, AC/DC, occur multiple times. To retrieve the unique singers, use the DISTINCT keyword before the singer column:
12SELECT DISTINCT singer FROM songs
Now there are no repeated values, so you can see that the total number of unique singers is 10.
Swipe to start coding
Find all unique title values in songs.
Lösning
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Completion rate improved to 4.17SQL Distinct
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Distinct is a keyword used with SELECT to return only unique values. Usually, you want to get all unique values, but there are duplicate values stored in the tables.
Check the difference: in our table, there are 18 records at all, and each record has a singer. You'll retrieve the 18 singers with the next query:
12SELECT singer FROM songs
But some singers, for example, AC/DC, occur multiple times. To retrieve the unique singers, use the DISTINCT keyword before the singer column:
12SELECT DISTINCT singer FROM songs
Now there are no repeated values, so you can see that the total number of unique singers is 10.
Swipe to start coding
Find all unique title values in songs.
Lösning
Byt till skrivbordet för praktisk övningFortsätt där du är med ett av alternativen nedanTack för dina kommentarer!
Awesome!
Completion rate improved to 4.17single
