public static <T extends Number> WindowOver<T> varSamp(Expression<T> expr) {
        return new WindowOver<T>(expr.getType(), SQLOps.VARSAMP, expr);
    }
returns the sample variance of a set of numbers after discarding the nulls in this set.

@param expr argument
@return var_samp(expr)
querydsl-sql/src/main/java/com/querydsl/sql/SQLExpressions.java