Dapper parameters in C#

Parameterized SQL from anonymous objects.

using Dapper;
using Microsoft.Data.Sqlite;

using var db = new SqliteConnection("Data Source=:memory:");
db.Execute("CREATE TABLE runs(lang TEXT, tpm INT)");
db.Execute("INSERT INTO runs VALUES ('csharp', 95), ('rust', 88)");

// anonymous objects carry parameters; Dapper handles the quoting
var fast = db.Query<int>(
    "SELECT tpm FROM runs WHERE lang = @Lang AND tpm > @Floor",
    new { Lang = "csharp", Floor = 90 });

Console.WriteLine(string.Join(",", fast));
Console.WriteLine(db.ExecuteScalar<long>("SELECT COUNT(*) FROM runs"));

How it works

1. @Lang and @Floor bind from the object's property names.
2. Parameters mean quoting and injection are Dapper's problem.
3. ExecuteScalar<long> fetches a single value with its type.

Keywords and builtins used here

• int
• long
• new
• string
• using
• var

The run, in numbers

Lines

14

Characters to type

532

Tokens

84

Three-star pace

85 tpm

At the three-star pace of 85 tokens a minute, this run takes about 59 seconds.

Type this snippet

Step 2 of 2 in Data with Dapper, step 5 of 16 in The open ecosystem.

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