How to find power of a number in SQLite

Question

I want to update the Interest field in my database. My SQL query is like as per below

Update Table_Name set Interest = Principal * Power(( 1 + (rate

Answer 1

If you are using SQLite NuGet package in a .NET project, you can write an extension method and bind it at runtime;

[SQLiteFunction("pow", 2, FunctionType.Scalar)]
public class SQLitePowerExtension : SQLiteFunction
{
    public override object Invoke(object[] args)
    {
        double num = (double)args[0];
        double exp = (double)args[1];

        return Math.Pow(num, exp);
    }
}

And then use it like this;

using (var conn = new SQLiteConnection("Data Source=:memory:"))
{
    conn.Open();
    conn.BindFunction(typeof(SQLitePowerExtension).GetCustomAttribute<SQLiteFunctionAttribute>(), new SQLitePowerExtension());

    var comm = new SQLiteCommand("CREATE TABLE test (num REAL, exp REAL, result REAL)", conn);
    comm.ExecuteNonQuery();

    // Populate with some data - not shown

    comm = new SQLiteCommand($"UPDATE test SET result = pow(num, exp))", conn);
    comm.ExecuteNonQuery();
}