Update column to the COUNT of rows for specific values in another column. SQL Server

Question

My Table is:

|ID |data | cr |
| 1 | AAA |    |
| 2 | AAA |    |
| 3 | AAA |    |
| 4 | BBB |    |
| 5 | CCC |    |
| 6 | BBB |    |

I need result:

|ID |data | cr |
| 1 | AAA | 3  |
| 2 | AAA | 3  |
| 3 | AAA | 3  |
| 4 | BBB | 2  |
| 5 | CCC | 1  |
| 6 | BBB | 2  |

Found this Update a column value to the COUNT of rows for specific values in same table and tried it:

UPDATE MyTbl a, 
        (SELECT data,COUNT(*) cnt 
            FROM MyTbl 
          GROUP BY data) b
    SET a.cr = b.cnt 
  WHERE a.data= b.data

SQL Server gives error :

Msg 102, Level 15, State 1, Line 1 Incorrect syntax near 'a'.
Msg 102, Level 15, State 1, Line 4 Incorrect syntax near 'b'.

Any idea how to do this in SQL Server (2014 Express).

Thanks in advance.

Answer 1

It should be Update..set...from. Try this one:

update a
set a.cr=b.cnt
from MyTbl a join
     (SELECT data,COUNT(*) cnt 
            FROM MyTbl 
          GROUP BY data) b on a.data=b.data

Result:

ID  data    cr
--------------
1   AAA     3
2   AAA     3
3   AAA     3
4   BBB     2
5   CCC     1
6   BBB     2

Demo in SQL Fiddle

Answer 2

Something like this

UPDATE t SET
    t.cr = vv.c
from MyTbl as t
left outer join 
(
    select count(*) as c , data from MyTbl group by data
) as vv on vv.data = t.data