对另一个相似表中具有匹配值的记录进行分组，计数和排除

Question

Select Gender, Count(*)as TotalGender
FROM 1
Group by Gender

This works perfect for me.

However, this table(1) has a similar column to another table(2).

If this similar column has matching values, I need to exclude those values from the above count.

Answer 1

Use a JOIN in that case, like this:

SELECT Gender, 
       COUNT(*) AS TotalGender
FROM `1` 
LEFT JOIN `2`
     ON `1.somecolumn` = `2.somecolumn`
WHERE `2.somecolumn` IS NULL
GROUP BY Gender