Abstract: Partially materialized views in the field of database systems are described herein. A method of partially materializing a view computed from one or more source tables comprises generating a view definition including a query expression and at least one control predicate referencing at least one control table. The query expression specifies the maximal content of the view, that is, the complete set of records that could be materialized. One or more control predicates and the contents of one or more control tables restrict what records are actually materialized and stored in the view. This allows the content of the partially materialized view to be adjusted simply by updating one or more control tables.

Abstract: A bionic cervix uteri dilator comprises a power supply circuit, an oscillating circuit, a voltage step-up circuit and curing electrodes, wherein the output terminal of the power supply circuit is connected to the input terminal of the oscillating circuit the output terminal of the oscillating circuit is connected to the input terminal of the voltage step-up circuit, and the output terminal of the voltage step-up circuit is connected to the curing electrodes. The present invention has advantages of novel structure, safety and reliability. With a narrow pulse of frequency 1-200 Hz (being preferably selected from 5 to 150 HZ, further being preferable in between 5-50 HZ.) outputted on the output terminal, the cervix uteri can be effectively dilated by stimulating ear acupoints, so that gynecological diseases treatments can be facilitated, and the pains caused by cervical dilating by the use of instruments can be alleviated. The present invention is worth widely popularizing and utilizing.