/// <summary>
/// 生成更新语句
/// </summary>
/// <returns></returns>
public override string BuildUpdate()
{
var fields = UpdateFields.Select(f => $"`{f}` = @{f}").ToList();
return($@"UPDATE {TableName} SET { string.Join(" , ", fields) } WHERE `{mPrimaryKeyName}` = @{mPrimaryKeyName}");
}