如何在SQL中使用复合键连接两个表？
Introduction Joining tables in SQL typically involves matching rows based on one or more keys. However, when dealing with composite keys—where two or more columns uniquely identify a row— it can...
在SQL中，使用复合键通过FULL OUTER JOIN连接Income_o和Outcome_o表，可以更全面地整合收入和支出数据。COALESCE函数可处理NULL值，确保所有组合均被显示，便于后续分析和决策。
