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Giorgi / DuckDB.NET

Bindings and ADO.NET Provider for DuckDB
https://duckdb.net
MIT License
343 stars 62 forks source link

CreateDataAdapter and DuckDbDataAdapter #68

Open bnuzhouwei opened 1 year ago

bnuzhouwei commented 1 year ago

There no DuckDbDataAdapter in the lib, can implement it?

lloydchriswilson commented 3 weeks ago

I have a database agnostic application that overrides System.Data.Common classes. It appears that several are missing like CommandBuilder and especially DataAdapter. Are there any plans to support these classes?

Thanks!

Giorgi commented 3 weeks ago

No plans currently.

lloydchriswilson commented 3 weeks ago

I think it is not too hard. Using the SQLite library as a go-by (not copying) I confirmed several things and wrote DuckDBCommandBuilder and DuckDBDataAdapter. The latter appears to be trivial, but CommandBuilder is about 200 lines of verbose VB code (can be easily converted to C#). I am stuck because the DuckDBDataReader class has an overridden method called GetSchemaTable which does not really give the information that DBCommandBuilder needs to create insert, etc., commands. Specifically, the field lengths and key field info is not placed in the schema table. I think you'd have to parse the select command to get the table name and then run the Describe command to extract the information needed (or use some other API call).

I'm providing this information (and my work so far) in case you decide to try to finish the work yourself. I don't feel confident enough with the database to fix GetSchemaTable myself. It is great that you have lots of the standard ADO.Net classes working; just adding a couple more like CommandBuilder and DataAdapter would provide much better functionality. Most of the hard work is already done in the System.Data.Common classes (as you know).

One other thing: in DuckDB when you set a query parameter name, all other providers I use (SQLite, SQL Server, Oracle, MySQL, etc.) are forgiving if you include the SQL prefix when defining the parameters (e.g., you can pass $PARM1 as the parameter name) and it works OK, however DuckDB requires that the name exclude the prefix (e.g., PARM1). It was easy to fix my code, but you might want to consider this.

DuckDB.Net.Data.zip

Giorgi commented 3 weeks ago

Thanks for investigation @lloydchriswilson. Can you send a PR for the parameter prefix issue?