/// tip | Dica

Você pode usar qualquer outra biblioteca de banco de dados SQL ou NoSQL que quiser (em alguns casos chamadas de <abbr title="Object Relational Mapper, um termo sofisticado para uma biblioteca onde algumas classes representam tabelas SQL e instâncias representam linhas nessas tabelas">"ORMs"</abbr>), o FastAPI não obriga você a usar nada. 😎

///

* `Field(primary_key=True)` tells SQLModel that the `id` is the **primary key** in the SQL database (you can learn more about SQL primary keys in the SQLModel docs).

    By having the type as `int | None`, SQLModel will know that this column should be an `INTEGER` in the SQL database and that it should be `NULLABLE`.

# SQL (关系型) 数据库

/// info

这些文档即将被更新。🎉

当前版本假设Pydantic v1和SQLAlchemy版本小于2。

新的文档将包括Pydantic v2以及 <a href="https://sqlmodel.tiangolo.com/" class="external-link" target="_blank">SQLModel</a>（也是基于SQLAlchemy），一旦SQLModel更新为为使用Pydantic v2。

///

**FastAPI**不需要你使用SQL(关系型)数据库。

但是您可以使用任何您想要的关系型数据库。

在这里，让我们看一个使用着[SQLAlchemy](https://www.sqlalchemy.org/)的示例。

您可以很容易地将其调整为任何SQLAlchemy支持的数据库，如：

* PostgreSQL
* MySQL

& 👆 🔜 💪 🔗 ⏮️ 👆 **FastAPI** 🈸, 👂 📊 ⚪️➡️ 🎰 💽:

<img src="/img/tutorial/sql-databases/image01.png">

## 🔗 ⏮️ 💽 🔗

🚥 👆 💚 🔬 🗄 💽 (📁) 🔗, ➡ FastAPI, ℹ 🚮 🎚, 🚮 🏓, 🏓, ⏺, 🔀 📊, ♒️. 👆 💪 ⚙️ <a href="https://sqlitebrowser.org/" class="external-link" target="_blank">💽 🖥 🗄</a>.

⚫️ 🔜 👀 💖 👉:

<img src="/img/tutorial/sql-databases/image02.png">

		}
		return sql.FromInt(v), nil
	case simdjson.TypeUint:
		v, err := iter.Int()
		if err != nil {
			// Can't fit into int, convert to float.
			v, err := iter.Float()
			return sql.FromFloat(v), err
		}
		return sql.FromInt(v), nil
	case simdjson.TypeBool:
		v, err := iter.Bool()
		if err != nil {
			return nil, err
		}
		return sql.FromBool(v), nil
	case simdjson.TypeNull:
		return sql.FromNull(), nil

func (r *Record) Clone(dst sql.Record) sql.Record {
	other, ok := dst.(*Record)
	if !ok {
		other = &Record{}
	}
	if len(other.KVS) > 0 {
		other.KVS = other.KVS[:0]
	}
	other.KVS = append(other.KVS, r.KVS...)
	return other
}

// Set - sets the value for a column name.
func (r *Record) Set(name string, value *sql.Value) (sql.Record, error) {
	var v interface{}

	fr, err := parquetgo.NewFileReader(rsc)
	if err != nil {
		return nil, errParquetParsingError(err)
	}

	return &Reader{Closer: rsc, r: fr}, nil
}

func (pr *Reader) Read(dst sql.Record) (rec sql.Record, rerr error) {
	nextRow, err := pr.r.NextRow()
	if err != nil {
		if err == io.EOF {
			return nil, err
		}
		return nil, errParquetParsingError(err)
	}

	kvs := jstream.KVS{}

		db.AddError(ErrUnsupportedDriver)
	}
	return db
}

// Exec executes raw sql
func (db *DB) Exec(sql string, values ...interface{}) (tx *DB) {
	tx = db.getInstance()
	tx.Statement.SQL = strings.Builder{}

	if strings.Contains(sql, "@") {
		clause.NamedExpr{SQL: sql, Vars: values}.Build(tx.Statement)
	} else {
		clause.Expr{SQL: sql, Vars: values}.Build(tx.Statement)
	}

	return tx.callbacks.Raw().Execute(tx)

		}
	}
	return db.Error
}

// DB returns `*sql.DB`
func (db *DB) DB() (*sql.DB, error) {
	connPool := db.ConnPool
	if db.Statement != nil && db.Statement.ConnPool != nil {
		connPool = db.Statement.ConnPool
	}
	if tx, ok := connPool.(*sql.Tx); ok && tx != nil {
		return (*sql.DB)(reflect.ValueOf(tx).Elem().FieldByName("db").UnsafePointer()), nil
	}

	if db.Statement.Schema != nil {
		for _, c := range db.Statement.Schema.QueryClauses {
			db.Statement.AddClause(c)
		}
	}

	if db.Statement.SQL.Len() == 0 {
		db.Statement.SQL.Grow(100)
		clauseSelect := clause.Select{Distinct: db.Statement.Distinct}

		if db.Statement.ReflectValue.Kind() == reflect.Struct && db.Statement.ReflectValue.Type() == db.Statement.Schema.ModelType {
			var conds []clause.Expression