Collation Order

Using the keyword COLLATE in a <value-expression> specifies the collation order to apply for a string column if you need a collation order that is different from the normal collation for this column.The normal collation order is defined by either the default collation for the database character set, or the collation set explicitly in the column’s definition.

The keyword NULLS defines where NULL in the associated column will fall in the sort order: NULLS FIRST places the rows with the NULL column above rows ordered by that column’s value;NULLS LAST places those rows after the ordered rows.

NULLS FIRST is the default.