ax-grdb

GRDB & SQLite

Quick Patterns

GRDB Setup

import GRDB

// DatabaseQueue (single connection, safe for all use cases)
let dbQueue = try DatabaseQueue(path: dbPath)

// DatabasePool (concurrent reads, single writer - better performance)
let dbPool = try DatabasePool(path: dbPath)

// In-memory for testing
let dbQueue = try DatabaseQueue()

GRDB Model Definition

struct Track: Codable, FetchableRecord, PersistableRecord {
    var id: Int64?
    var title: String
    var artist: String
    var duration: TimeInterval
    var playCount: Int

    // Table name (default: "track")
    static let databaseTableName = "tracks"

    // Auto-increment
    mutating func didInsert(_ inserted: InsertionSuccess) {
        id = inserted.rowID
    }
}

GRDB Raw SQL Queries

// Read
let tracks = try dbQueue.read { db in
    try Track.fetchAll(db, sql: """
        SELECT * FROM tracks
        WHERE artist = ? AND duration > ?
        ORDER BY title
        LIMIT 50
        """, arguments: ["Artist", 180])
}

// Single row
let track = try dbQueue.read { db in
    try Track.fetchOne(db, sql: "SELECT * FROM tracks WHERE id = ?", arguments: [42])
}

// Aggregate
let count = try dbQueue.read { db in
    try Int.fetchOne(db, sql: "SELECT COUNT(*) FROM tracks WHERE playCount > 0")!
}

// Write
try dbQueue.write { db in
    var track = Track(id: nil, title: "Song", artist: "Artist", duration: 210, playCount: 0)
    try track.insert(db)
}

// Update
try dbQueue.write { db in
    try db.execute(sql: "UPDATE tracks SET playCount = playCount + 1 WHERE id = ?", arguments: [42])
}

// Delete
try dbQueue.write { db in
    try db.execute(sql: "DELETE FROM tracks WHERE playCount = 0")
}

GRDB Type-Safe Query Interface

let tracks = try dbQueue.read { db in
    try Track
        .filter(Column("artist") == "Artist")
        .filter(Column("duration") > 180)
        .order(Column("title"))
        .limit(50)
        .fetchAll(db)
}

// Joins
struct TrackInfo: Decodable, FetchableRecord {
    var trackTitle: String
    var artistName: String
}

let infos = try dbQueue.read { db in
    try Track
        .joining(required: Track.artist)
        .select(
            Column("title").forKey("trackTitle"),
            Artist.Columns.name.forKey("artistName")
        )
        .asRequest(of: TrackInfo.self)
        .fetchAll(db)
}