Why Do My Database Saves Disappear After Closing My .NET Application?

Troubleshooting Database Save Issues in .NET

Losing database changes after seemingly successful saves in .NET applications is a common headache. This article pinpoints a frequent cause: database saves that work during debugging but vanish upon application closure.

The Pitfall of |DataDirectory|

The culprit often lies in using the |DataDirectory| placeholder in your database connection string. While convenient during development (pointing to the project's output directory), it creates a problem. Visual Studio, upon application closure, may overwrite your modified database file with the original, undoing your work. This usually happens because the database file is set to "Copy Always" in project properties.

Resolving the Overwrite Issue

The solution involves adjusting the database file's "Copy to Output Directory" setting. Change it to "Copy if Newer" or, preferably, "Never Copy." This prevents Visual Studio from automatically replacing your saved database file.

For enhanced debugging, consider creating a separate connection in Server Explorer that directly targets the database file in the output directory. This lets you track changes without impacting the original project file.

Crucial Consideration for MS Access

A special note for MS Access users: Even simple table access can modify the database's timestamp. This can trigger an overwrite. Therefore, setting the "Copy to Output Directory" property to "Never Copy" is strongly recommended for MS Access databases.

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