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This article mainly explains "how to understand ADO MoveNext". The content of the explanation is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "how to understand ADO MoveNext".

We first modify the attributes of the entity class to support open concurrency, and then simulate a sequence of concurrency to see how to handle concurrency conflicts.

The in-memory representation of the data is in ADO, and the in-memory representation of the data is a recordset. In ADO MoveNext, it is a dataset. There are important differences between them. The recordset of the number of tables looks like a single table. If the recordset will contain data from multiple database tables, it must use JOIN queries to combine the data from each database table into a single result table.

Instead, a dataset is a collection of one or more tables. Tables in a dataset are called data tables; specifically, they are ADO MoveNext objects. If a dataset contains data from multiple database tables, it will typically contain multiple DataTable objects. That is, each DataTable object usually corresponds to a single database table or view. In this way, the dataset can mimic the structure of the underlying database.

Datasets usually also contain relationships. A relationship within a dataset is similar to a foreign key relationship in a database, that is, it associates rows in multiple tables with each other. For example, if the dataset contains a table about investors and another table about stock purchases for each investor, the dataset may also contain a relationship to connect the rows of the investor table with the corresponding rows of the purchasing table.

Because a dataset can hold multiple independent tables and maintain information about the relationships between tables, it can hold much richer data structures than recordsets, including self-associated tables and tables with many-to-many relationships. Data navigation and cursors in ADO, you use the ADO MoveNext method to sequentially scan the rows of the recordset. In ADO.NET, rows are represented as collections, so you can go through the table in turn as you would through any collection,.

Or access specific rows through an ordinal index or a primary key index. The DataRelation object maintains information about master and detail records and provides methods to enable you to obtain records related to the record you are working on. For example, starting with the row of "Nate Sun" in the Investor table, you can navigate to the set of rows in the Purchase table that describe its purchase.

Cursors are database elements that control the ability to record navigation, update data, and the visibility of changes made by other users to the database. ADO MoveNext does not have an inherent cursor object, but rather contains data classes that provide traditional cursor functionality. For example, forward-only, read-only cursors are provided in the ADO.NET DataReader object.

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