How to Set Database Foreign Keys

1 year ago
Emily Johnson
1 minute

When setting foreign keys for a database table, it is necessary to use the FOREIGN KEY constraint. Below is an example SQL statement for creating a database table with a foreign key.

CREATE TABLE 表名 (
    列1 数据类型,
    列2 数据类型,
    列3 数据类型,
    FOREIGN KEY (外键列) REFERENCES 另一个表名(关联列)
);

In the example above, the foreign key column is the column in the current table that contains the foreign key, the other table name is the name of the other table to be related, and the join column is the column used for the join in the other table.

It is important to note that before setting a foreign key, it is necessary to ensure that the referenced column is unique and has already been indexed. Additionally, it is also important to ensure that the data type of the referenced column matches the data type of the foreign key column.

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