What should my daily intake of calories be? Within a healthy, balanced diet, a man needs around 10,500kJ (2,500Kcal) a day to maintain his weight. For a woman, that figure is around 8,400kJ (2,000Kcal) a day. These values can vary depending on age, metabolism and levels of physical activity, among other things.
A foreign key, simply stated, is another table's primary key. The values in a foreign key field match values in the primary key, indicating that the two records are related â for example, a customer and an order that she has placed. Unlike primary keys: A table can have more than one foreign key.
A foreign key places constraints on data in the related tables, which enables MySQL to maintain referential integrity. Letâs take a look at the following database diagram in the sample database. We have two tables: customers and orders. Each customer has zero or more orders and each order belongs to only one customer.ySQL drop foreign key. You also use the ALTER TABLE statement to drop foreign key as the following statement: 1. 2. ALTER TABLE table_name. DROP FOREIGN KEY constraint_name. In the statement above: 1  First, you specify the table name from which you want to remove the foreign key.