就是笛卡尔积,用 select * from 视图1 cross join 视图2; 应该也行。我也觉得这样写好奇怪啊。实际上视图1和视图2都是从多个数据表检索出来的。视图1 SELECT ID, YEAR FROM TABLE1 JOIN TABLE2 ON ... JOIN TABLE 3 ON ...视图2 SELECT SUM(AMT1) AS AMT2, SUM(AMT2) AMT2 FROM TABLE4 JOIN TABLE5 ON ...TABLE 1-5各不相同,TABLE1-3和TABLE4-5之间没用明显联系。我应该怎么才能写出比较正常的SQL语句呢?
就是笛卡尔积,用
select * from 视图1 cross join 视图2;
应该也行。我也觉得这样写好奇怪啊。实际上视图1和视图2都是从多个数据表检索出来的。视图1
SELECT ID, YEAR FROM TABLE1 JOIN TABLE2 ON ... JOIN TABLE 3 ON ...视图2
SELECT SUM(AMT1) AS AMT2, SUM(AMT2) AMT2 FROM TABLE4 JOIN TABLE5 ON ...TABLE 1-5各不相同,TABLE1-3和TABLE4-5之间没用明显联系。我应该怎么才能写出比较正常的SQL语句呢?