按Oracle SQL中其他字段中的唯一值计数

我有这样的桌子：

Year    Month   Type
2013    4   31
2013    3   31
2014    5   40
2014    6   41
2015    5   31
2015    7   40
2013    4   31
2013    3   31
2014    5   40
2014    6   41
2015    5   31
2015    7   40
2013    4   31
2013    3   31

Year    Month   Type    Count_of_appearance
2013    3   31  3
2013    4   31  3
etc..           

我想数一数每种组合的出现次数。所以输出应该是这样的：

Year    Month   Type
2013    4   31
2013    3   31
2014    5   40
2014    6   41
2015    5   31
2015    7   40
2013    4   31
2013    3   31
2014    5   40
2014    6   41
2015    5   31
2015    7   40
2013    4   31
2013    3   31

Year    Month   Type    Count_of_appearance
2013    3   31  3
2013    4   31  3
etc..           

我一直在使用类似于：

SELECT Year,
       Month,
       Type,
       (SELECT COUNT (*)
          FROM myTable
         WHERE (...im lost in defining a condition in order to make this work...)
           AS Count_of_appearance
  FROM employee;

我不知道如何定义函数WHERE子句

---

问题是我有很多像这样的字段和很多独特的值。表是8Gb大。

您正在查找的

分组依据：

SELECT Year, Month, Type, COUNT(*) AS Count_of_appearance
FROM employee
GROUP BY Year, Month, Type
ORDER BY Year, Month, Type;

为了确保结果的顺序正确，您还应该包括一个
orderby