ORDBMS提供类型构造器，用于构造复杂对象的数据类型，主要的类型构造器为：组合(记录)、集合、 【19】 。

Today I took part in the English singing competition of our school. Most of the singers and audience have been there when I arrived at the ball. See the large audience, I started to feel little nervous. After some times, it was my turn to sing. When the host read my name out, the audience burst into a great cheer, and my heart began to beat really fastly. The song I sing was Country Road, that is a very famous piece of American country music. I had practiced for it many times, and I didn’t think I had done a very good job. Anyway, I was still very excited because of participating was the most important thing to me.