在mysql中查找四个表中最大的值(Find the greatest value among four tables in mysql)

在mysql中查找四个表中最大的值(Find the greatest value among four tables in mysql)

我有四个表中的产品，客户，商店，世界在MySQL中具有相同名称的日期列。 我想要做的是我想在所有四张表的DATE COLUMN中找到最大的日期 。 我不希望每桌的最佳约会，而是所有四桌中最大的约会。 我希望你能理解。 请帮帮我

I have a column Date with the same name in four tables Products, Customers, Shops, World in mysql. what i want to do is that i want to find the greatest date in the DATE COLUMN of all four tables. I don't want the greatest date of every table but the greatest one in all four tables. I hope you are understanding. Please help me

最满意答案

我能想到的最有效的方法是使用greatest功能：

select greatest( (select max(date) from products), (select max(date) from customers), (select max(date) from shops), (select max(date) from world) ) greatest_date

SQLFiddle演示

The most efficient way I can think of would be using the greatest function:

select greatest( (select max(date) from products), (select max(date) from customers), (select max(date) from shops), (select max(date) from world) ) greatest_date

SQLFiddle demo