如何按2列计算记录数

Question

In MySQL I have a table.

Example:

id name type
1 Thomas 2
2 Thomas 2
3 Thomas 1
4   Paul 3
5   Paul 4
6   Paul 4

I need calculate same records by 2 columns. Result for this example should be:

name   type   countOfRecords
Thomas 2       2
Thomas 1       1
Paul   3       1
Paul   4       2

Could you help me with this request?

Answer 1

Since you want records in your result set for each name and type <name,type> pair you need to group by name and type .

SELECT 
name,
type,
COUNT(*) countOfRecords
FROM your_table
GROUP BY name,type;

Note:

Group BY <some column> would generate a result set where number of rows = number of distinct / different / unique <some column> .

Same holds for multiple columns in GROUP BY clause.

Answer 2

This may be right solution:

SELECT  name, type, COUNT(*) as countOfRecords
FROM your_table
GROUP BY name,type;