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# `sqlmo`
`sqlmo` is a set of primitives to represent SQL tables and queries. Use these primitives to:
- **Auto-generate migrations**: Load SQL representations in a standardized form (`sqlmo::Schema`), calculate differences between 
schemas (`sqlmo::Migration`), and generate SQL to apply the migration (`sqlmo::Migration::to_sql`).
- **Build SQL queries**: Represent SQL queries in a data model, to create APIs for query generation. Then, generate the
SQL query. *Note: this library does not support parsing SQL queries (yet).*

For auto-generating migrations, there are a few built-in schema sources:
- **Postgres**: [`sqlmo_sqlx`](./sqlmo_sqlx)
- **OpenAPI v3**: [`sqlmo_openapi`](./sqlmo_openapi)

If you need another source, you should define a way to build a `sqlmo::Schema` from your data source, then use `sqlmo` 
to auto-generate migrations.

Current tools that support this:

- [`ormlite`](https://github.com/kurtbuilds/ormlite)

If you use this library, submit a PR to be added to this list.

## Usage

This example reads the schema from a postgres database, defines an empty schema (which should be filled in),
and then computes the migration to apply to the database.

```rust
use sqlmo_sqlx::FromPostgres;

#[tokio::main]
async fn main() {
    let url = std::env::var("DATABASE_URL").unwrap();
    let mut conn = sqlx::postgres::PgConnection::connect(&url).await?;
    let current = Schema::try_from_postgres(&mut conn, schema_name).await?;
    let end_state = Schema::default(); // Load your end-state by manually defining it, or building it from another source
    let migration = current.migrate_to(end_state, &sqlmo::Options::default());
    
    for statement in migration.statements {
        let statement = statement.to_sql(Dialect::Postgres);
        println!("{}", statement);
    }
}
```

# Roadmap

- [ ] When calculating migrations, create commented out lines for column deletion
- [ ] ? When calculating migrations, do alter column by calculating word distance between column names