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sqlselectdistinct

MySQL: Select DISTINCT / UNIQUE, but return all columns?

SELECT DISTINCT field1, field2, field3, ......
FROM table;

I am trying to accomplish the following SQL statement, but I want it to return all columns.
Is this possible?

Something like this:

SELECT DISTINCT field1, * 
FROM table;
Solution

  • You're looking for a group by:

    select *
from table
group by field1

    Which can occasionally be written with a distinct on statement:

    select distinct on field1 *
from table

    On most platforms, however, neither of the above will work because the behavior on the other columns is unspecified. (The first works in MySQL, if that's what you're using.)

    You could fetch the distinct fields and stick to picking a single arbitrary row each time.

    On some platforms (e.g. PostgreSQL, Oracle, T-SQL) this can be done directly using window functions:

    select *
from (
   select *,
          row_number() over (partition by field1 order by field2) as row_number
   from table
   ) as rows
where row_number = 1

    On others (MySQL, SQLite), you'll need to write subqueries that will make you join the entire table with itself (example), so not recommended.