If the line appears solid, the DBMS enforces referential integrity for the relationship when rows are added or modified in the foreign-key table.

如果为实线，则当在外键表中添加或修改行时，DBMS将强制关系的引用完整性。

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If the line appears dotted, the DBMS does not enforce referential integrity for the relationship when rows are added or modified in the foreign-key table.

如果为点线，则当在外键表中添加或修改行时，DBMS不强制关系的引用完整性。

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For foreign key creation, another table with a primary key with a compatible data type is required.

对于创建外键，则需要另外一个具有主键的表，且该主键具有兼容的数据类型。

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