Path prefix fixes, directory exists fix, SqlServer compability

[trusek]

fixes exists - not working properly for checking directories
fixes writeStream - updating size not working for SqlServer
fixes delete - file name was not prefixed
change exists - not working propery under SqlServer
change writeStream - on exception file name in message was prefixed

[fracsi]

EXISTS already a boolean operator in SQL.

[trusek]

Yes, but for mssql that is inncorect syntax. You can check this on (https://sqliteonline.com/)

SELECT EXISTS (SELECT 1)

throws: Token error: 'Incorrect syntax near the keyword 'exists'.'

When on Sqlite, PostgreSql, MariaDb, Mysql works like a charm.
Case-When syntax should work on every engine.

But on Oracle still missing from DUAL. On this could be patched with simple

$this->connection->getDatabasePlatform()->getDummySelectSQL('CASE WHEN EXISTS(...`)

[fracsi]

getDummySelect wont work. E.g.: DB2.
Currently the bundle supports: sqlite, mysql , mariadb and pgsql.
If we need to add more platform, a refactor is needed to handle platform-specific queries i guess. Not just some if-else in the adapter.

[trusek]

The package is great, I just miss support for SQLserver.I'm not intrested with others like Oracle or DB2.

I'm not familiar with DB2. Doctrine do sprintf('SELECT %s FROM sysibm.sysdummy1', $expression); for this platform.

[fracsi]

Please create a table definition for SQLServer in the schema folder. See the existing ones for examples.