Dart
CRUD
Learn CRUD operations with sqflite.
CRUD operations
CRUD stands for four basic database operations: Create, Read, Update, Delete. sqflite offers these via db.insert, db.query, db.update and db.delete.
Example: await db.insert('notes', {'title': 'Merhaba'}); adds a new row. final rows = await db.query('notes'); pulls all rows. Each row comes as a Map<String, dynamic>; rows[0]['title'] gives the first row's title.
Inserting and querying rows
To add a row you call db.insert('table', map). The map binds column names to values; for example {'title': 'Merhaba', 'body': 'İlk notum'}.
To query rows you use db.query('table'). The result is a List<Map<String, dynamic>>. rows[0]['title'] gives the first row's title column. In this lesson we will write a crudDemo function: it inserts a note, queries all notes and prints the first note's title.
Exercise Insert and query a note
The code below imports sqflite and main opens a Database. Define crudDemo(Database db): insert a note with db.insert('notes', {'title': 'Merhaba', 'body': 'First note'}), query all notes with db.query('notes') and print the first note's title with print('First note: ${rows[0]['title']}'). main already has print('CRUD: insert + query'); add the crudDemo(db) call.
Show example solution
import 'package:sqflite/sqflite.dart';
Future<void> crudDemo(Database db) async {
await db.insert('notes', {'title': 'Merhaba', 'body': 'First note'});
final rows = await db.query('notes');
print('First note: ${rows[0]["title"]}');
}
void main() async {
print('CRUD: insert + query');
final db = await openDatabase('notes.db');
await crudDemo(db);
await db.close();
}
Test yourself
-
Match the CRUD methods
- db.insert
- Create
- db.query
- Read
- db.update
- Update
- db.delete
- Delete
-
Which method adds a new row?
- db.insert
- db.delete
- db.update
- db.query
Show answer
db.insert — db.insert adds a new row (Create).
-
The db.insert call
await db.____('notes', {'title': 'Merhaba', 'body': 'First note'});
Show answer
await db.insert('notes', {'title': 'Merhaba', 'body': 'First note'});
Next lesson: Transaction
