sqlsrv (MSSQL) support.

[ilexei]

In database.php there is a section, describing MS SQL server connection

        'pgsql' => [
            'driver' => 'pgsql',
            'url' => env('DATABASE_URL'),
            'host' => env('DB_HOST', '127.0.0.1'),
            'port' => env('DB_PORT', '5432'),
            'database' => env('DB_DATABASE', 'forge'),
            'username' => env('DB_USERNAME', 'forge'),
            'password' => env('DB_PASSWORD', ''),
            'charset' => 'utf8',
            'prefix' => '',
            'prefix_indexes' => true,
            'schema' => 'public',
            'sslmode' => 'prefer',
        ],

I tested the connection and there are some issues with that.

1. The sqlsrv driver is not installed in the docker
   It could be fixed like this

RUN apt-get update && apt-get install -y gnupg2
RUN curl https://packages.microsoft.com/keys/microsoft.asc | apt-key add - 
RUN curl https://packages.microsoft.com/config/ubuntu/20.04/prod.list > /etc/apt/sources.list.d/mssql-release.list 

RUN apt-get update 
RUN ACCEPT_EULA=Y apt-get -y --no-install-recommends install msodbcsql17 unixodbc-dev 
RUN pecl install sqlsrv
RUN pecl install pdo_sqlsrv
RUN docker-php-ext-enable sqlsrv pdo_sqlsrv

I verified it but did not optimize: maybe another version of ubuntu should be set or some packages were installed previously.
2. In some queries the collation is hardcoded
collation('utf8mb4_bin')
This type of collation is not supported by MS SQL, so the easy way is to redefine it with
DB_COLLATION env var or use it from the connection.
3. The SQL syntax
ALTER TABLE .* MODIFY is not supported in the MS SQL. So, the migrations fail on this step. As a work-around I replaced MODIFY with env('SPECIAL_MODIFY', 'MODIFY'), but it looks hacky. Then I can pass ALTER COLUMN as SPECIAL_MODIFY.
4. The last thing, which blocked me completely, is again ALTER TABLE
"ALTER TABLE lessons MODIFY raw_text MEDIUMBLOB". Unfortunately, even if the table is empty, MS SQL cannot change the column type.
[Microsoft][ODBC Driver 17 for SQL Server][SQL Server]Implicit conversion from data type nvarchar(max) to varbinary(max) is not allowed. Use the CONVERT function to run this query.
I stuck here, unfortunately.
So, this is "feature request" I assume. Or, if there are any suggestions on overcoming the problem - I'm ready to test it!