schema change not implemented

"schema change not implemented" 的意思是“模式更改未实现”。这通常是指在数据库中尝试进行更改模式的操作，但该操作未被实现或不受支持。可能需要检查数据库版本或使用其他方法来实现所需的更改。

相关问题

oracle schema does not exist

This error message indicates that the schema you are trying to access does not exist in the Oracle database.

You can check if the schema exists by querying the ALL_USERS view:

SELECT * FROM ALL_USERS WHERE USERNAME='<schema_name>';

If the schema does not exist, you will need to create it. To create a schema in Oracle, you can use the CREATE USER statement:

CREATE USER <schema_name> IDENTIFIED BY <password>;

Note that you will need appropriate privileges to create a user/schema.

If the schema does exist and you are still receiving this error, make sure that you are connecting to the correct database and that the schema is not locked or inaccessible. You can also check the spelling and case of the schema name to ensure that it matches exactly.

Schema is not a constructor

在学习mongoose的用法时，你遇到了一个问题，报错显示"Schema is not a constructor"。这个问题通常是由于在定义模式时使用了错误的构造函数导致的。根据你提供的引用内容，可以看出你在定义模式时使用了错误的构造函数。具体来说，你使用了小写的mongoose.schema而正确的构造函数应该是mongoose.Schema（大写S）。 这是因为mongoose的模块导出的是一个对象，其中包含了Schema的构造函数。正确的写法应该是使用大写的S来引用构造函数，例如const { Schema } = mongoose; 。通过修改你的代码，使用大写的mongoose.Schema来定义模式，你应该能够解决这个问题。<span class="em">1</span><span class="em">2</span><span class="em">3</span>
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