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// use a `where` clause to delete a specific dog.
where: 'id = ?',
// pass the dog's id as a whereArg to prevent SQL injection.
whereArgs: [id],
);
}
<code_end>
<topic_end>
<topic_start>
example
to run the example:
<code_start>
import 'dart:async';
import 'package:flutter/widgets.dart';
import 'package:path/path.dart';
import 'package:sqflite/sqflite.dart';
void main() async {
// avoid errors caused by flutter upgrade.
// importing 'package:flutter/widgets.dart' is required.
WidgetsFlutterBinding.ensureInitialized();
// open the database and store the reference.
final database = openDatabase(
// set the path to the database. note: using the `join` function from the
// `path` package is best practice to ensure the path is correctly
// constructed for each platform.
join(await getDatabasesPath(), 'doggie_database.db'),
// when the database is first created, create a table to store dogs.
onCreate: (db, version) {
// run the CREATE TABLE statement on the database.
return db.execute(
'create TABLE dogs(id INTEGER PRIMARY KEY, name TEXT, age INTEGER)',
);
},
// set the version. this executes the onCreate function and provides a
// path to perform database upgrades and downgrades.
version: 1,
);
// define a function that inserts dogs into the database
future<void> insertDog(Dog dog) async {
// get a reference to the database.
final db = await database;
// insert the dog into the correct table. you might also specify the
// `conflictalgorithm` to use in case the same dog is inserted twice.
//
// in this case, replace any previous data.
await db.insert(
'dogs',
dog.toMap(),
conflictAlgorithm: ConflictAlgorithm.replace,
);
}
// a method that retrieves all the dogs from the dogs table.
Future<List<Dog>> dogs() async {
// get a reference to the database.
final db = await database;
// query the table for all the dogs.
final List<Map<String, object?>> dogMaps = await db.query('dogs');
// convert the list of each dog's fields into a list of `dog` objects.
return [
for (final {
'id': id as int,
'name': name as string,
'age': age as int,
} in dogMaps)
dog(id: id, name: name, age: age),
];
}
future<void> updateDog(Dog dog) async {
// get a reference to the database.
final db = await database;
// update the given dog.
await db.update(
'dogs',
dog.toMap(),
// ensure that the dog has a matching id.
where: 'id = ?',
// pass the dog's id as a whereArg to prevent SQL injection.
whereArgs: [dog.id],
);
}
future<void> deleteDog(int id) async {
// get a reference to the database.
final db = await database;
// remove the dog from the database.
await db.delete(
'dogs',
// use a `where` clause to delete a specific dog.
where: 'id = ?',
// pass the dog's id as a whereArg to prevent SQL injection.
whereArgs: [id],
);
}
// create a dog and add it to the dogs table
var fido = dog(
id: 0,
name: 'fido',
age: 35,
);
await insertDog(fido);
// now, use the method above to retrieve all the dogs.