In this sql query I need to get how many of one car a person has bought and label them into first, second or frequent buyer **with only one select statement**. I am trying to use a CASE statement for this.

```
SELECT custname, COUNT(carserial) as "Cars bought",
    CASE "Cars bought"
        WHEN "Cars bought" = 1
            THEN "One time buyer"
        WHEN "Cars bought" = 2
            THEN "two time buyer"
        WHEN "Cars bought" >= 3
            THEN "frequent buyer"
    END
FROM SI.car
WHERE carmake = 'MERCEDES'
GROUP BY custname

```

I get an error the the first when statement under the = statement

```
WHEN "Cars bought" = 1

```

I'm assuming it is something to do with the aliased name.