Make a change to the database with Prisma.js without having to reset the whole thing

Question

How can make a change to the database with Prisma.js without having to reset the whole thing?

if I have used this command

npx prisma migrate dev --name role-makeOptional-NormalizedName

I will lose all of the data in my database but I don't lose my data.

In my case I wanted to change String to String? in schema.prisma file

NormalizedName  String?            @unique @db.VarChar(64)

Is there a proper command to avoid losing the data?

Answer 1

Go into your schema and make the change:

NormalizedName  String            @unique @db.VarChar(64)
NormalizedName  String?            @unique @db.VarChar(64)

Then create a draft migration:

$ npx prisma migrate dev --name migration-name --create-only

Then edit the migration in SQL (this allow null values ie optional)

ALTER TABLE myTable ALTER COLUMN myColumn {DataType} NULL;

OR Postgres

ALTER TABLE myTable ALTER COLUMN myColumn DROP NOT NULL;

etc.

Then apply the modified SQL:

$ npx prisma migrate dev

I hope this works for you :)