/// <summary>
/// Query FirstOrDefault
/// 匹配的第一个实体，如果没有匹配的实体，则选择默认值。
/// </summary>
/// <typeparam name="TEntity">类型参数</typeparam>
/// <param name="connection">DbConnection</param>
/// <param name="predicate">条件表达式目录树</param>
/// <returns>TEntity 集合</returns>
public static TEntity FirstOrDefault <TEntity>(this IDbConnection connection, Expression <Func <TEntity, bool> > predicate)
{
try
{
return(DommelMapper.FirstOrDefault(connection, predicate));
}
catch (Exception ex) { throw new Exception(ex.Message); }
}