实现简单的同现约束验证。

Implementing simple co-occurrence constraint validation.

youdao

索引扫描实际上是对父表进行主键查找，并完成外键约束验证。

The latter is actually a primary key lookup against the parent table and constitutes the foreign key constraint verification.

youdao

如果我想从We b层查找约束验证，我该如何去做？又能获得什么？

If I want to look up the constraint validations from the web tier how do I do this and what do I get back?

youdao