Failed to set binary column to null using Update on MSSQL

[avtc]

Updating a model containing null in bytes[] property causes an error:
"Implicit conversion from data type nvarchar to varbinary is not allowed. Use the CONVERT function to run this query."

This is the cause of passing parameters as Dictionary<string, object> to Dapper.
Dapper converts the dictionary to DynamicParameters without knowing the DbType of the passed null value.
SqlDbCommand adds the new parameter with DbType.String (by default) and null convered to DbNull.Value.
For binary and varbinary columns DBNull.Value does not work without setting the DbType, while other column types works fine.

Reference code in Dapper: https://github.com/DapperLib/Dapper/blob/a31dfd3dd4d7f3f2580bd33c877199d7ef3e3ef9/Dapper/DynamicParameters.cs#L271

[vdaron]

Fixed in develop, Thanks for the MR !