June 2010
Intermediate to advanced
328 pages
7h 51m
English
Content preview from SQL Antipatterns
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Solution: Create an Intersection Table
Instead of storing the account_id in the Products table, store it in a separate table, so each individual value of that attribute occupies a separate row. This new table Contacts implements a many-to-many relationship between Products and Accounts:
| Jaywalking/soln/create.sql | |
| | CREATE TABLE Contacts ( |
| | product_id BIGINT UNSIGNED NOT NULL, |
| | account_id BIGINT UNSIGNED NOT NULL, |
| | PRIMARY KEY (product_id, account_id), |
| | FOREIGN KEY (product_id) REFERENCES Products(product_id), |
| | FOREIGN KEY (account_id) REFERENCES Accounts(account_id) |
| | ); |
| | |
| | INSERT INTO Contacts (product_id, account_id) |
| | VALUES (123, 12), (123, 34), (345, 23), (567, 12), (567, 34); |
When the table has foreign ...
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