[Copied]oracle single-table Query de-weight (one way of higher efficiency)

Source: Internet
Author: User

1 Select 2     *    3  from4      (5         Select6A.*, RowNum r_n7          from 8 a_test A9 ) TTTen where OneTt.r_ninch  A     ( -         Select  -             min(rownum) the          from  - a_test T -         Group  byname//name for the de-weight field -)

The query principle is:

The table is grouped by the field you want to go to, and the minimum row number for each group after grouping is queried to take these records out of the table as a filter.

(Note: This method is for network acquisition, and does not have a lot of data to test, do not know how efficient)

[Copied]oracle single-table Query de-weight (one way of higher efficiency)

Related Article

Contact Us

The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion; products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the content of the page makes you feel confusing, please write us an email, we will handle the problem within 5 days after receiving your email.

If you find any instances of plagiarism from the community, please send an email to: info-contact@alibabacloud.com and provide relevant evidence. A staff member will contact you within 5 working days.

A Free Trial That Lets You Build Big!

Start building with 50+ products and up to 12 months usage for Elastic Compute Service

  • Sales Support

    1 on 1 presale consultation

  • After-Sales Support

    24/7 Technical Support 6 Free Tickets per Quarter Faster Response

  • Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.