Denis

PostgreSQL tests failed because of #4917 I fixed and checked tests at the local environment

This pull request doesn't affect enums mapped to integer values at database. Enums mapped to integers will have [IntTypeMapping type](https://github.com/linq2db/linq2db/pull/4945/files#diff-64cde6986d0f512d3d0bdeb17e38cb140ee52f088a3dc96ff71989193a51880eR399), so pull request does't affect them. Mapping changed only for...

@igor-tkachev @sdanyliv @MaceWindu @viceroypenguin @jods4 @Shane32 Hi, do you have a chance to review the pull request?

I added a test

Can be fixed like that ```cs LinqToDBForEFTools.Implementation = new MyLinqToDBForEFTools(); public class MyLinqToDBForEFTools : LinqToDBForEFToolsImplDefault { public override EFConnectionInfo ExtractConnectionInfo(IDbContextOptions? options) => new() { ConnectionString = "value" }; } ```

I found a workaround ```cs public class MyLinqToDBForEFToolsImpl : LinqToDBForEFToolsImplDefault { public override MappingSchema CreateMappingSchema(IModel model, IMetadataReader? metadataReader, IValueConverterSelector? convertorSelector, DataOptions dataOptions) { var mappingSchema = base.CreateMappingSchema(model, metadataReader, convertorSelector, dataOptions);...

It is unexpectable that constructor of SqlDataType class throws an exception. I think it is better to create a DbDataType when it not found by DataType ```cs internal static SqlDataType?...

I think it's not a bug, mapping schema exists in internal collection Schemas of DataContext.MappingSchema 

And you can use linq2db version 6.0.0-preview.4, it doesn't throws an exception related to DatePart

It fixed in linq2db 6.0.0-preview.4