SQL - 两个表的 COUNT() 行 GROUP BY 一个表中的一列

Question

I have two tables. One table is the main table that holds most of the information. it has basically two important columns:

table2_id
type

The second table has only one of those columns and that's id. However, I have to GROUP BY type since that's what I am needing. But problem occurs because if I GROUP BY id on a joined statement it doesn't give me correct information. I am needing the other table to get matches AND mismatches from the first table.

EXAMPLE table 1:

id        type
100       admin
101       user
102       author
103       editor
104       customer

EXAMPLE table 2:

id
100
100
101
101
110
120
100
100

My Results need to look like:

type     total(COUNT()IN TABLE1)  intable2andtable1    difference
admin       200                         100                100
user        120                         100                 20
author      205                         200                  5
editor      80                           70                 10
customer    300                         100                200 

So, some how I need to JOIN and COUNT() the tables. I was able to get the actual total from the first table. However, if I try to do anything with the ID it makes me add it to the GROUP BY clause and that's messing up my results.

Here is what I have tried:

SELECT type , count(*) as total
FROM table1
GROUP BY type

and that will return:

type     total(COUNT()IN TABLE1)
admin       200 
user        120
author      205
editor      80
customer    300

However, I cannot get the second table involved and showing me the differences between the two.

EDIT: Here is a sqlfiddle to make it clearer. http://sqlfiddle.com/#!15/08951/2/0

Answer 1

It's not entirely clear what the common field between your tables 1 and 2 is, however, assuming it's id , this query should be what you're after:

SELECT type,
  COUNT(t1.version_id) as t1_total,
  COUNT(t2.version_id) as t2_total,
  COUNT(t1.version_id) - COUNT(t2.version_id) as difference
FROM table1 t1
    LEFT JOIN table2 t2 ON t1.id = t2.id
GROUP BY type
ORDER BY type ASC

Updated SQL Fiddle here: http://sqlfiddle.com/#!15/08951/20

Answer 2

From what I understand, you would like to count how many times each type is represented in table2, correct? How about this:

SELECT table1.type, COUNT(table2.id) 
FROM table2 INNER JOIN table1 ON table1.id = table2.id
GROUP BY table2.id`  

It should display something like this:

admin  4
user   2