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:


              12
            
SELECT 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:


              12
            
SELECT DISTINCT singer
FROM songs

Now there are no repeated values, so you can see that the total number of unique singers is 10.

Opgave

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Find all unique title values in songs.

Løsning

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Sektion 1. Kapitel 4

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:


              12
            
SELECT 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:


              12
            
SELECT DISTINCT singer
FROM songs

Now there are no repeated values, so you can see that the total number of unique singers is 10.

Opgave

Swipe to start coding

Find all unique title values in songs.

Løsning

Skift til skrivebord for at øve i den virkelige verdenFortsæt der, hvor du er, med en af nedenstående muligheder

Var alt klart?

Tak for dine kommentarer!

Sektion 1. Kapitel 4

Skift til skrivebord for at øve i den virkelige verdenFortsæt der, hvor du er, med en af nedenstående muligheder