> For the complete documentation index, see [llms.txt](https://dotnetweb30-ke.gitbook.io/ke/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://dotnetweb30-ke.gitbook.io/ke/construction-db/data-access-layer.md).

# Data Access Layer

- [Manage connection strings and objects](https://dotnetweb30-ke.gitbook.io/ke/construction-db/data-access-layer/manage-connection-strings-and-objects.md)
- [Working with data providers](https://dotnetweb30-ke.gitbook.io/ke/construction-db/data-access-layer/working-with-data-providers.md)
- [Connect to a data source by using a generic data access interface](https://dotnetweb30-ke.gitbook.io/ke/construction-db/data-access-layer/connect-to-a-data-source-by-using-a-generic-data-access-interface.md)
- [Handle and diagnose database connection exceptions](https://dotnetweb30-ke.gitbook.io/ke/construction-db/data-access-layer/handle-and-diagnose-database-connection-exceptions.md)
- [Manage exceptions when selecting, modifying data](https://dotnetweb30-ke.gitbook.io/ke/construction-db/data-access-layer/manage-exceptions-when-selecting-modifying-data.md)
- [Build command objects and query data from data sources](https://dotnetweb30-ke.gitbook.io/ke/construction-db/data-access-layer/build-command-objects-and-query-data-from-data-sources.md)
- [Retrieve data source by using the DataReader](https://dotnetweb30-ke.gitbook.io/ke/construction-db/data-access-layer/retrieve-data-source-by-using-the-datareader.md)
- [Manage data by using the DataAdapter and TableAdapter](https://dotnetweb30-ke.gitbook.io/ke/construction-db/data-access-layer/manage-data-by-using-the-dataadapter-and-tableadapter.md)
- [Updating data](https://dotnetweb30-ke.gitbook.io/ke/construction-db/data-access-layer/updating-data.md)
- [Entity Framework](https://dotnetweb30-ke.gitbook.io/ke/construction-db/data-access-layer/entity-framework.md)
- [Query data sources by using EF](https://dotnetweb30-ke.gitbook.io/ke/construction-db/data-access-layer/entity-framework/query-data-sources-by-using-ef.md)
- [Code First to existing DB](https://dotnetweb30-ke.gitbook.io/ke/construction-db/data-access-layer/entity-framework/code-first-to-existing-db.md)
- [Entity Data Modeling Fundamentals](https://dotnetweb30-ke.gitbook.io/ke/construction-db/data-access-layer/entity-framework/entity-data-modeling-fundamentals.md)
- [Querying Data](https://dotnetweb30-ke.gitbook.io/ke/construction-db/data-access-layer/entity-framework/querying-data.md)
- [Data modification](https://dotnetweb30-ke.gitbook.io/ke/construction-db/data-access-layer/entity-framework/data-modification.md)