add MS SQL Server dialect.

[igalklebanov]

might close #38.

This PR adds a core dialect for MS SQL Server. It uses the tedious library as the underlying driver, and the tarn library for connection pool management. All external code is provided through the dialect's config upon instantiation.
It also introduces MS SQL Server to our testing suites.
It also makes necessary small refactors in our testing suites, being more explicit about what's being tested, now that we have more than 3 core dialects.

---

Gaps in our querying or schema APIs relevant to mssql that should be addressed in future PRs:

1. implement the output clause so insert id can be retrieved. add OUTPUT clause support. #828
2. implement merge queries to support on conflict like queries. add MERGE query support. #700
3. implement identity method @ column builders. add IDENTITY column support. #823
4. add bit, uniqueidentifier, nvarchar data types.
5. add persisted @ column builders.
6. ability to create things if they don't exist - if possible.
7. docs site - getting started, other places that mention dialects. Mssql docs #724
8. computed columns.
9. or alter view.
10. from at create type.
11. support setting data type and more things (e.g. not null) in the same alter column clause.
12. json_value(ref, <json_path>). add eb.jsonPath<$>. #791
13. json helpers, if possible. add mssql json helpers. #818
14. top N support. add TOP clause support. #821
15. limit offset support. add FETCH clause support. #822

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Name	Status	Preview	Comments	Updated (UTC)
kysely	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Sep 9, 2023 0:11am

[sofanati-nour]

Igal doing the lord's work right here, thank you so much.

[MartinEide]

Often these sql servers are hosted in azure. Put any thought into authentication using azure active directory?
Or is the connection with mssql purely handled by mssql?

Maybe a dumb question.
https://learn.microsoft.com/en-us/azure/azure-sql/database/azure-sql-javascript-mssql-quickstart

import * as dotenv from 'dotenv';
import sql from 'mssql';
dotenv.config({ path: `.env.${process.env.NODE_ENV}`, debug: true });

const server = process.env.AZURE_SQL_SERVER;
const database = process.env.AZURE_SQL_DATABASE;
const port = parseInt(process.env.AZURE_SQL_PORT);
const type = process.env.AZURE_SQL_AUTHENTICATIONTYPE;


export const config = {
    server,
    port,
    database,
    authentication: {
        type
    },
    options: {
        encrypt: true
    }
};

sql.connect(config);

Update:
Looked further into the PR. Understand that you used tedious:
https://tediousjs.github.io/tedious/api-connection.html#event_connect

And in the docs of tedious there are different authentication types. Including azure-active-directory-default.
So i'd guess you just configure your tedious configuration into the mssqlDialect?

[igalklebanov]

@MartinEide we're unopinionated by design. always refer to the underlying driver's (tedious in this case) docs for connection options.

I have no idea, never used ms sql server in production.

[dylel]

It appears that limit(1) isn't converted correctly, currently it adds it to the end of the select statement, however in sql server its called TOP instead of limit.

SQL SERVER: SELECT TOP(1) * FROM dbo.MyTable
MySQL: SELECT * FROM dbo.MyTable LIMIT 1

I don't think it can be used anywhere else apart from directly after the select keyword and might need to be hoisted there somehow. Maybe it would be better to add a completely different method like .top(1) but I realise that would stray from the current api. It's likely that offset will cause a similar issue as I think mysql can specify offset, limit in one line where as sql server separates them completely but I'm not that familiar with mysql.

Is there another way to call limit in a query, raw sql? i'm currently using this in a nested sub query and would be happy to not have to add a method or touch the current api to get this to work if there was some other way.

I've been putting this through its paces and seems to be pretty solid overall as this was the only thing I found so far, its my first time really diving into kysely but I'll keep reporting in as I explore the feasibility of bringing my c# codebase to typescript.

TLDR: looks great so far

[igalklebanov]

@dylel This PR only handles the mssql dialect and introducing mssql to our existing test suites (which is a lot). Anything related to querying APIs will or will not be dealt with in other PRs if and when this PR is merged.

Check the tests to see how I managed to pull things off, usually using modifyX methods that allow raw SQL before/after certain keywords. These are temporary workarounds.

[vicary]

@dylel Do you think it's a good idea to normalize it into OFFSET X ROWS FETCH NEXT Y ROWS ONLY instead of TOP X?

[dylel]

@dylel Do you think it's a good idea to normalize it into OFFSET X ROWS FETCH NEXT Y ROWS ONLY instead of TOP X?

I think the verbose solution would be better, and have them be completely separate methods. I don't like the idea of introducing 'TOP X' and would be in favor of just polyfiling .limit() to have a case for mssql so that users can just use the same api and not have to carry the mental model of "i'm using sql server therefore I have to call a different method" but i'm sure @igalklebanov has some thoughts for future PR's. I've been successfully using the modifyStart/End functions for the time being and they work well for now

[vicary]

I don't think TOP X is a good idea, because .offset() never works. Unless we want to conditionally appends the SQL, depends on whether user has called .offset(). This sounds not quite consistent with the current simple approach.

If we are going the offset ... fetch route, we may start with visitSelectQuery, visiLimit and visiOffset in mssql-query-compiler.ts. Here is a patch file.

It leaves one question, order by and offset is always required for this clause. Are users responsible for calling .orderBy() and .offset() themselves?

@dylel @igalklebanov wdyt?

[koskimas]

Finally got to reviewing this giant! Amazing work! I have nothing to nitpick here. Let's merge this and improve as we go 💯

[movahhedi]

When will this be released? Need it soo much

[movahhedi]

Guys? Any updates?

[koskimas]

This is now released with 0.27.0

[movahhedi]

Thanks for making our lives easier! 🎉🥳