/// 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">

	sql = dryRunDB.Or("a = ? or b = ?", "a", "b").Unscoped().Find(&User{}).Statement.SQL.String()
	if !regexp.MustCompile(`WHERE a = .+ or b = .+$`).MatchString(sql) {
		t.Fatalf("invalid sql generated, got %v", sql)
	}

	sql = dryRunDB.Not("a = ? or b = ?", "a", "b").Unscoped().Find(&User{}).Statement.SQL.String()
	if !regexp.MustCompile(`WHERE NOT \(a = .+ or b = .+\)$`).MatchString(sql) {
		t.Fatalf("invalid sql generated, got %v", sql)
	}
}

	}

	data := ScannerValuerStruct{
		Name:     sql.NullString{String: "name", Valid: true},
		Gender:   &sql.NullString{String: "M", Valid: true},
		Age:      sql.NullInt64{Int64: 18, Valid: true},
		Male:     sql.NullBool{Bool: true, Valid: true},
		Height:   sql.NullFloat64{Float64: 1.8888, Valid: true},
		Birthday: sql.NullTime{Time: time.Now(), Valid: true},
		Allergen: NullString{sql.NullString{String: "Allergen", Valid: true}},

//
// /////////////////////////////////////////////////////////////////////
func errExpressionTooLong(err error) *s3Error {
	return &s3Error{
		code:       "ExpressionTooLong",
		message:    "The SQL expression is too long: The maximum byte-length for the SQL expression is 256 KB.",
		statusCode: 400,
		cause:      err,
	}
}

func errColumnTooLong(err error) *s3Error {
	return &s3Error{
		code:       "ColumnTooLong",

		t.Errorf("Table with escape character, got %v", r.Statement.SQL.String())
	}

	r = dryDB.Table("user as u").Select("name").Find(&User{}).Statement
	if !regexp.MustCompile("SELECT .name. FROM user as u WHERE .u.\\..deleted_at. IS NULL").MatchString(r.Statement.SQL.String()) {
		t.Errorf("Table with escape character, got %v", r.Statement.SQL.String())
	}

            return (java.sql.Date) src;
        }
        if (src instanceof Date) {
            return new java.sql.Date(((Date) src).getTime());
        }
        if (src instanceof Calendar) {
            return new java.sql.Date(((Calendar) src).getTimeInMillis());
        }
        final String str = src.toString();
        if (isEmpty(str)) {
            return null;
        }

		}
	case *int, *int8, *int16, *int32, *int64,
		*uint, *uint8, *uint16, *uint32, *uint64, *uintptr,
		*float32, *float64,
		*bool, *string, *time.Time,
		*sql.NullInt32, *sql.NullInt64, *sql.NullFloat64,
		*sql.NullBool, *sql.NullString, *sql.NullTime:
		for initialized || rows.Next() {
			initialized = false
			db.RowsAffected++
			db.AddError(rows.Scan(dest))
		}
	default:
		var (