How to get exact rows count of particular column in MySQL table

Question

I want to get exact row count of specified column

Example: Table

Name            Id          Age
_______________________________
  Jon           1           30
 Merry          2           40
 William                    50
 David        

There are 4 rows in table but i want to count ID column.

I am using below query to achieve it

select count(Id) from table;

But its returning 4 and I know why it is returning 4 but I want output as 2 because there are only two rows in Id column.

How can i achieve it?

Answer 1

尝试这个：

select count(Id) from table where id>0;

Answer 2

在@blabla_bingo 和@Edwin Dijk 的帮助下，我终于通过以下查询实现了它

select count(Id) from table where Id!="";

Answer 3

如果列Id的值为空字符串 ("") 而不是NULL ，则使用以下查询

SELECT COUNT(Id) FROM table WHERE Id <> ''