摘要:
store_information表格: Geography表格:store_namesalesdateLos Angeles15001999-01-05San Diego2501999-01-07Los Angeles3001999-01-08Boston7001999-01-08region_namestore_nameEastBostonEastNew YorkWestLos AngelesWestSan Diego1. 查询:# 基本查询SELECT store_name FROM store_information#DISTINCT去除重复行SELECT DISTINCT store 阅读全文