如何将三个结果集合并成一个显示

代码如下：
select sbkjdate,count(1) from sbgreen
where gzdmqsw between '0001' and '3099'
group by sbkjdate

select sbkjdate, count(1) from sbgreen
where gzdmzjlw between '01' and '40' and gzdmqsw between '0001' and '3099'
group by sbkjdate

select sbkjdate,count(1) from sbgreen
where gzdmzjlw between '70' and '99' and gzdmqsw between '0001' and '3099'
group by sbkjdate

这是从一张表中去数据，由于条件不一样不知道如何将这三个结果集进行合并，请大家指点。

这个可以合并成一个sql语句 条件之间用 or。即将三个sql语句 的条件用括起来用or连接起来。重点：建议看看是否还有优化的地方