/// <summary>
/// Execute a query that return a single value
/// </summary>
/// <example>
/// int maxAgeUnder50 = db.Scalar<Person, int>(x => Sql.Max(x.Age));
/// </example>
/// <param name="field">The expression that return the single value</param>
/// <typeparam name="T">The Type specifying the target table</typeparam>
/// <typeparam name="TKey">The Type of the result</typeparam>
/// <returns></returns>
public async Task <TKey> GetScalarAsync <T, TKey>(Expression <Func <T, TKey> > field)
{
var select = new TypedSelectStatement <T>(DialectProvider);
select.Select(field);
return(await this.ExecuteScalarAsync <TKey>(
DialectProvider.ToSelectStatement(select.Statement, CommandFlags.None)));
}
/// <summary>An OrmConnection method that gets a scalar.</summary>
/// <typeparam name="T"> Generic type parameter.</typeparam>
/// <typeparam name="TKey">Type of the key.</typeparam>
/// <param name="field"> The field.</param>
/// <returns>The scalar.</returns>
public async Task <TKey> GetScalarAsync <T, TKey>(Expression <Func <T, TKey> > field)
{
//int maxAgeUnder50 = db.Scalar<Person, int>(x => Sql.Max(x.Age));
TypedSelectStatement <T> select = new TypedSelectStatement <T>(DialectProvider);
select.Select(field);
return(await this.ExecuteScalarAsync <TKey>(DialectProvider.ToSelectStatement(select.Statement, CommandFlags.None)));
}