Issue description

In MSSQL, when using the "find" method with where conditions on a "varchar" column, the query runner fails to specify the parameter type, causing performance issues.

Refer

Expected Behavior

Typeorm should handle the parameter input to node-mssql correctly

Actual Behavior

According to the node-mssql driver docs, the input type defaults to a JS data type. However, for "varchar," it appears to conflict with "nvarchar," leading to the wrong data type being used in queries.

As a result, runtime data conversion occurs, significantly impacting query performance (our application crashed under high load due to this issue).

For now, we're using a workaround by executing raw queries and manually handling SQL parameters. This resolved the performance issue, but it should be handled by the ORM itself.

Steps to reproduce

1. Define a varchar column

@Index()
@Column({ type: 'varchar', nullable: true })
 memberId: string | null

2. Query the entity with where condition on that column

this.somEntityRepo.find({ where: { memberId: "someValue" } })

On a large dataset, you can verify the resources used by this query.

Workaround which resolved the performance issue

 await this.connection.query(`SELECT * FROM "someEntity" WHERE "memberId" = ${'someValue'}`)

My Environment

Additional Context

No response

Relevant Database Driver(s)

• aurora-mysql
• aurora-postgres
• better-sqlite3
• cockroachdb
• cordova
• expo
• mongodb
• mysql
• nativescript
• oracle
• postgres
• react-native
• sap
• spanner
• sqlite
• sqlite-abstract
• sqljs
• sqlserver

Are you willing to resolve this issue by submitting a Pull Request?

Yes, I have the time, but I don't know how to start. I would need guidance.