d2sqlite3

1 // Note: exception handling is left aside for clarity.
2 import d2sqlite3;
3 import std.typecons : Nullable;
4 
5 // Open a database in memory.
6 auto db = Database(":memory:");
7 
8 // Create a table
9 db.run("DROP TABLE IF EXISTS person;
10         CREATE TABLE person (
11           id    INTEGER PRIMARY KEY,
12           name  TEXT NOT NULL,
13           score FLOAT
14         )");
15 
16 // Prepare an INSERT statement
17 Statement statement = db.prepare(
18     "INSERT INTO person (name, score)
19      VALUES (:name, :score)"
20 );
21 
22 // Bind values one by one (by parameter name or index)
23 statement.bind(":name", "John");
24 statement.bind(2, 77.5);
25 statement.execute();
26 statement.reset(); // Need to reset the statement after execution.
27 
28 // Bind muliple values at the same time
29 statement.bindAll("John", null);
30 statement.execute();
31 statement.reset();
32 
33 // Bind, execute and reset in one call
34 statement.inject("Clara", 88.1);
35 
36 // Count the changes
37 assert(db.totalChanges == 3);
38 
39 // Count the Johns in the table.
40 auto count = db.execute("SELECT count(*) FROM person WHERE name == 'John'")
41                .oneValue!long;
42 assert(count == 2);
43 
44 // Read the data from the table lazily
45 ResultRange results = db.execute("SELECT * FROM person");
46 foreach (Row row; results)
47 {
48     // Retrieve "id", which is the column at index 0, and contains an int,
49     // e.g. using the peek function (best performance).
50     auto id = row.peek!long(0);
51 
52     // Retrieve "name", e.g. using opIndex(string), which returns a ColumnData.
53     auto name = row["name"].as!string;
54 
55     // Retrieve "score", which is at index 2, e.g. using the peek function,
56     // using a Nullable type
57     auto score = row.peek!(Nullable!double)(2);
58     if (!score.isNull)
59     {
60         // ...
61     }
62 }