【文件属性】:
文件名称:非等值连接-复杂查询技术-连接
文件大小:671KB
文件格式:PPT
更新时间:2021-04-25 22:11:30
sql
非等值连接
EMPLOYEES
JOB_GRADES
…
*
在EMPLOYEES 表中的工
资必须在JOB_GRADES 表
中的最低工资和最高工资之间
Non-Equijoins
A non-equijoin is a join condition containing something other than an equality operator.
The relationship between the EMPLOYEES table and the JOB_GRADES table has an example of a non-equijoin. A relationship between the two tables is that the SALARY column in the EMPLOYEES table must be between the values in the LOWEST_SALARY and HIGHEST_SALARY columns of the JOB_GRADES table. The relationship is obtained using an operator other than equals (=).