Improvements to database migrations

[ajcvickers]

This is a grouping of related issues. Feel free to vote (👍) for this issue to indicate that this is an area that you think we should spend time on, but consider also voting for individual issues for things you consider especially important.

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This an "epic" issue for the theme of miscellaneous improvements to Migrations. Specific pieces of work will be tracked by linked issues.

Done in 6.0

• Allow defining column order via [ColumnAttribute.Order] when creating tables #10059
• Preserve DeleteBehavior when scaffolding a database created by EF Core #21252

Done in 7.0

• Add inheritdoc to migration files #10695
• Add a warning when store-generated PK is not supported #11162
• SQL Server Migrations: Handle AlterColumn(nullable: false) #21765

Backlog

• Design: Modernize generated C# #14545
• Enable nullability in migrations and model snapshots #18950
• Allow FKs to exist in the model but avoid creating them in the database #15854
• Support "unconstrained" foreign key relationships #13146
• Allow alternate keys to exist in the model but avoid creating them in the database #28226
• Migrations: Provider-rendered annotations in code #6546
• Enable compositional approach of custom migration functionality #17740
• Make it easier to flow custom annotations through to Migrations #10258
• Rebuild column when migrating from computed to non-computed #14075
• Add a way to specify mapping for migrations data operations #11548
• Migrations are too aggressive on RenameColumn #15178
• Migrations: SnapshotModelProcessor not used when generating SQL #18708
• Stream migration commands #19710
• Can't convert byte[] to string #20159
• Migrations script: wrap queries in sp_executesql when using --idempotent #27729
• Idempotent Migrations on HasDefaultValueSql or HasComputedColumnSql with line breaks adds whitespace #20391
• Support for data masking in sql server provider #20592
• Consider adding AlterIndexOperation to Migrations #20692
• Consider using Verbatim String Generation if absolutely sure will not contain linebreaks #20723
• Create check constraints for columns that are only conditionally nullable #20931
• Throw a better exception message when attempting to use LocalDB with memory-optimized tables #21779
• Don't scaffold unnecessary "Navigation" calls in the snapshot #21964
• Migrations: Allow access to IServiceProvider #10660
• Migrations: Use caller information for better errors #22515
• Tools: Add -WhatIf parameter to Update-Database #1775
• SqlServer Migrations: Rebuild primary keys when column type changed #16758
• Reset Identity column in migration if seed or increment changes #16964
• SqlServer Migrations: Rebuild column when IDENTITY changes #2100
• SqlServer Migrations: Rebuild primary keys when column collation changes #26115
• SqlServer Migrations: Rebuild foreign keys #12586
• SqlServer Migrations: Rebuild check constraints #18965
• Drop/create SQLite columns when changing column type to something not convertible #22598
• SQLite - Can't insert null into TIMESTAMP column #20475