Oracle SQL多表查询
曾经一段时间我对oracle的多表查询搞的云里雾里，究其原因：oracle自己的语法和SQL国际标准语法混用。此文章仅适合oracle 菜鸟，老鸟直接飞过… 多表连接类型（SQL 1999标准） • Cross joins • Natural joins • USING clause • Full (or two-sided) outer joins • Arbitrary join conditions for outer joins SQL1999语法： SELECT table1.column, table2.column FROM table1 [CROSS JOIN table2] | [NATURAL JOIN table2] | [JOIN table2 USING (column_name)] | [JOIN table2 ON (table1.column_name = table2.column_name)]| [LEFT|RIGHT|FULL OUTER JOIN table2 ON (table1.column_name = table2.column_name)]| [CROSS JOIN table2]; 语法解释： table1.column --指明从中检索数据的表和列 CROSS JOIN --返回两个表的笛卡尔集 NATURAL JOIN -