/// <summary>
/// 为数字减少val
/// </summary>
/// <param name="key"></param>
/// <param name="val">可以为负</param>
/// <returns>减少后的值</returns>
public async Task <long> StringDecrementAsync(string key, long val = 1)
{
return(await CsRedisHelper.IncrementAsync(key, 0 - val));
}
