public static <T> SQLQuery<T> selectDistinct(Expression<T> expr) {
        return new SQLQuery<Void>().select(expr).distinct();
    }
Create a new detached SQLQuery instance with the given projection

@param expr distinct projection
@param <T>
@return select(distinct expr)
querydsl-sql/src/main/java/com/querydsl/sql/SQLExpressions.java