I have a table of customers that has repetition of first names and last names. I don't know what type of select query should I use to display specific row regarding their same entries.
Example: Table: customers
customer_id|firstname|lastname
-----------+---------+---------
0000000001 |Peter |Griffin
0000000002 |Peter |Pan
0000000003 |Mary |Magdalene
0000000003 |Mary |Jane
And the output I want is like is:
customer_id|firstname|lastname
-----------+---------+---------
0000000001 |Peter |Griffin
0000000003 |Mary |Magdalene
I know this is easy but I'm new to SQL.
One way to do this is with DISTINCT ON:
SELECT DISTINCT ON (firstname)
customer_id, firstname, lastname
FROM customers
ORDER BY firstname, customer_id;
See:
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