zeus
92 lines
2.2 KiB
Markdown
92 lines
2.2 KiB
Markdown
# SQL, Prepared Statements, Rows, and Values
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SQL is the fundamental language for accessing SQLite databases.
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## Overview
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This section of the documentation focuses on low-level SQLite concepts: the SQL language, prepared statements, database rows and values.
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If SQL is not your cup of tea, jump to <doc:QueryInterface> 🙂
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## SQL Support
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GRDB has a wide support for SQL.
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Once connected with one of the <doc:DatabaseConnections>, you can execute raw SQL statements:
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```swift
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try dbQueue.write { db in
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try db.execute(sql: """
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INSERT INTO player (name, score) VALUES (?, ?);
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INSERT INTO player (name, score) VALUES (?, ?);
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""", arguments: ["Arthur", 500, "Barbara", 1000])
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}
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```
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Build a prepared ``Statement`` and lazily iterate a ``DatabaseCursor`` of ``Row``:
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```swift
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try dbQueue.read { db in
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let sql = "SELECT id, score FROM player WHERE name = ?"
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let statement = try db.makeStatement(sql: sql)
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let rows = try Row.fetchCursor(statement, arguments: ["O'Brien"])
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while let row = try rows.next() {
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let id: Int64 = row[0]
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let score: Int = row[1]
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}
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}
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```
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Leverage ``SQLRequest`` and ``FetchableRecord`` for defining streamlined apis with powerful SQL interpolation features:
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```swift
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struct Player: Decodable {
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var id: Int64
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var name: String
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var score: Int
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}
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extension Player: FetchableRecord {
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static func filter(name: String) -> SQLRequest<Player> {
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"SELECT * FROM player WHERE name = \(name)"
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}
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static func maximumScore() -> SQLRequest<Int> {
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"SELECT MAX(score) FROM player"
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}
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}
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try dbQueue.read { db in
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let players = try Player.filter(name: "O'Reilly").fetchAll(db) // [Player]
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let maxScore = try Player.maximumScore().fetchOne(db) // Int?
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}
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```
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For a more detailed overview, see [SQLite API](https://github.com/groue/GRDB.swift/blob/master/README.md#sqlite-api).
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## Topics
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### Fundamental Database Types
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- ``Statement``
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- ``Row``
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- ``DatabaseValue``
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- ``DatabaseCursor``
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### SQL Literals and Requests
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- ``SQL``
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- ``SQLRequest``
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- ``databaseQuestionMarks(count:)``
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### Database Values
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- ``DatabaseDateComponents``
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- ``DatabaseValueConvertible``
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- ``StatementColumnConvertible``
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### Supporting Types
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- ``Cursor``
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- ``FetchRequest``
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