SQL - 使用来自同一表的不同子集中的行的值更新表子集中的值

Question

Effectively, I would like to update values in a subset of an SQL table using values from an alternate subset of that same table. Take the following dataframe representation as an example:

   Company Employee        Type  Value
0        X        A  Category A     10
1        X        A  Category B      5
2        X        A  Category C      4
3        X        A  Category D      0
4        X        A  Category E      0
5        X        A  Category F      0
6        X        A  Category G      9
7        X        B  Category A     15
8        X        B  Category B      8
9        X        B  Category C      6
10       X        B  Category D      0
11       X        B  Category E      0
12       X        B  Category F      0
13       X        B  Category G      7

For both Employee A and Employee B, I would like to update Value where Type is in the set (Category D, Category E, Category F) with the corresponding value in Value where Type is in the set (Category A, Category B, Category C). Thus my desired outcome would be as follows:

   Company Employee        Type  Value
0        X        A  Category A     10
1        X        A  Category B      5
2        X        A  Category C      4
3        X        A  Category D     10
4        X        A  Category E      5
5        X        A  Category F      4
6        X        A  Category G      9
7        X        B  Category A     15
8        X        B  Category B      8
9        X        B  Category C      6
10       X        B  Category D     15
11       X        B  Category E      8
12       X        B  Category F      6
13       X        B  Category G      7

What would be the most effective way of doing this in MySQL? My attempt was the following:

UPDATE new_table 
SET 
    Value = (SELECT 
            Value
        FROM
            (SELECT 
                *
            FROM
                new_table) t
        WHERE
            Type IN ('Category A', 'Category B', 'Category C'))
WHERE
    Type IN ('Category D', 'Category E', 'Category F');

*My real column names are different than the above, as I assume these are reserved names

Answer 1

Update

Based on OP comments, there needs to be a Type translation table which indicates where the new value should come from for a given category:

UPDATE new_table t1
JOIN (SELECT 'C1' AS Cat1, 'C4' AS Cat2
      UNION ALL
      SELECT 'C2' AS Cat1, 'C5' AS Cat2
      UNION ALL
      SELECT 'C3' AS Cat1, 'C6' AS Cat2
      ) cats ON cats.Cat2 = t1.Type
JOIN new_table t2 ON t2.Employee = t1.Employee AND t2.Type = cats.Cat1
SET t1.Value= t2.Value

Demo on SQLFiddle

Original Answer

Since you have a direct relationship between the Type values, you can take advantage of that in your update query by JOIN ing new_table to itself where the difference in Type is 3 and updating Value from the JOIN ed table:

UPDATE new_table t1
JOIN new_table t2 ON t2.Employee = t1.Employee AND t2.Type = t1.Type - 3
SET t1.Value= t2.Value
WHERE t1.Type in (4, 5, 6);

Demo on SQLFiddle