SQLiteExpress is a Swift library implementing a lightweight wrapper for the C API of SQLite3 on macOS and iOS. SQLiteExpress provides
- an object-oriented data model,
- a clear separation of errors, expressed as exceptions, from results and side-effects, and
- uses Swift programming paradigms throughout its implementation.
This is done without changing the programming protocol of the C API of SQLite3. SQLiteEpress does not provide any help in crafting SQL statements, e.g. in a type-safe manner. If this functionality is needed, other SQLite wrappers are more suitable.
The following code snippet gives a flavor of how SQLiteExpress is used. The code snippet does the following things:
- It creates a new in-memory database
- It creates a new table in the database
- It enters data into the new table
- It queries the new table for some data
// Create a new in-memory database `db` and require extended errors to be thrown.
let db = try SQLiteDatabase(extendedErrors: true)
// Create a new table in `db`.
let stmt0 = try db.prepare(sql: """
CREATE TABLE Contacts (
id INTEGER PRIMARY KEY,
name TEXT NOT NULL,
email TEXT NOT NULL UNIQUE,
phone TEXT
);
""")
try stmt0.step()
stmt0.finalize()
// Enter two rows into the new table.
let stmt1 = try db.prepare(sql: """
INSERT INTO Contacts VALUES (?, ?, ?, ?);
""")
try stmt1.bind(integer: 1000, toParam: 1)
try stmt1.bind(text: "Mickey Mouse", toParam: 2)
try stmt1.bind(text: "[email protected]", toParam: 3)
try stmt1.bind(text: "+1 101-123-456", toParam: 4)
try stmt1.step()
try stmt1.bind(integer: 1001, toParam: 1)
try stmt1.bind(text: "Donald Duck", toParam: 2)
try stmt1.bind(text: "[email protected]", toParam: 3)
try stmt1.bind(text: "+1 101-123-456", toParam: 4)
try stmt1.step()
stmt1.finalize()
// Cound the number of distinct phone numbers.
let stmt2 = try db.prepare(sql: """
SELECT COUNT(DISTINCT phone) FROM Contacts;
""")
try stmt2.step()
let phoneNumbers = try stmt2.int(atColumn: 0)
Swift.print("Number of distinct phone numbers: \(phoneNumbers)")
stmt2.finalize()
// Show all names and email addresses from the `Contacts` table.
let stmt3 = try db.prepare(sql: """
SELECT name, email FROM Contacts;
""")
Swift.print("Entries in table:")
while try !stmt3.step() {
Swift.print("\(try stmt3.text(atColumn: 0)!), \(try stmt3.text(atColumn: 1)!)")
}
stmt3.finalize()When executed, the code prints out the following lines:
Number of distinct phone numbers: 1
Entries in table:
Mickey Mouse, [email protected]
Donald Duck, [email protected]
The following technologies are needed to build the components of the Swift SQLiteExpress framework:
Author: Matthias Zenger ([email protected])
Copyright © 2020 Google LLC.
Please note: This is not an official Google product.