CODEWITHSUNDEEP
sqldatabasetable-structure
Ulphat
Ulphat

Reputation: 782

How to store family relationship information with 1 record

Lets consider that we have Person A. Person F is his father, person M is his mother, person B is his brother and person S is his son. Each person may have many relations. Thats why, we have to create new relationship table like following:

persons

+----+------+
| id | name |
+----+------+
| 1  | A    |
| 2  | F    |
| 3  | M    |
| 4  | B    |
| 5  | S    |
+----+------+

relationship type

+----+---------+
| id | value   |
+----+---------+
| 1  | Father  |
| 2  | Mother  |
| 3  | Brother |
| 4  | Son     |
| 5  | Wife    |
| 6  | Husband |
+----+---------+

relationship

+----+----------+------------+------+
| id | PersonID | RelativeID | Type |
+----+----------+------------+------+
| 1  | 1        | 2          | 1    |
| 2  | 1        | 3          | 2    |
| 3  | 1        | 4          | 3    |
| 4  | 1        | 5          | 4    |
| 5  | 2        | 1          | 4    |
| 6  | 2        | 3          | 5    |
| 7  | 3        | 1          | 4    |
| ......                            |
+----+----------+------------+------+

In this case 1st row means that 2 is father of 1 (for IDs) and 5th row means that 1 is son of 2. In the real world these 2 rows are equivalent, but if I don't insert one of this rows, I cannot get missing rows meaning using existed row.

The question is: How to make structure, which contains these 2 meanings in 1 row?

Upvotes: 6

Views: 1725

Answers (1)

void
void

Reputation: 7890

In fact between 2 relatives we have 2 relation:

Person A is person B`s wife <=> Person B is person A`s husband
Person C is person D`s sister <=>Person D is person C`s brother (D is male)
Etc...

so if you provide a Reverse_Relation_Type column for your third table (relationship), then your problem will get solved and you will not have redundant data al all, you will have:

+----+----------+------------+---------------+-----------------------+
| id | PersonID | RelativeID | Relation_Type | Reverse_Relation_Type |
+----+----------+------------+---------------+-----------------------+
| 1  | 1        | 2          | 1             |4                      |
| 2  | 1        | 3          | 2             |4                      |
| 3  | 1        | 4          | 3             |3                      |
| 4  | 1        | 5          | 4             |6                      |
| 6  | 2        | 3          | 5             |1                      |
| ......                                                             |
+----+----------+------------+---------------+-----------------------+

Upvotes: 3

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