1 概述 1 概述 如下例子，你觉得有什么问题？如你能很快的找出问题，并且解决它，那么你可以跳过本篇文章，谢谢~~。 想一分钟，OK，如果没想出来，可以往下看，下图标注处即为问题处。 ok，本篇文章就是来解决该问题的。也就是接下来要与大家分享的System.DBNULL类型。 2 内容分享 2 内容
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=969390
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=969364
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=969335
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=969316
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=969300
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=969277
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=969247
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=969226
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=969203
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=969179
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=969145
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=969121
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=969065
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=969046
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=969018
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968992
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968973
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968946
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968912
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968883
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968855
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968819
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968798
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968773
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968742
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968700
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968658
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968633
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968596
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968561
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968520
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968501
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968454
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968415
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968380
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968351
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968318
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968277
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968237
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968207
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968178
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968159
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968145
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968125
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968095
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968065
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968036
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968008
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967974
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967919
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967892
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967854
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967829
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967780
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967744
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967702
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967666
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967634
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967591
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967492
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967440
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967379
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967315
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967256
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967209
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967159
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967078
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=966836
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=966371
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=966337
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=966298
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=966252
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=966220
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=966183
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=966148
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=966114
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=966083
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=966017
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965992
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965959
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965925
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965891
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965863
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965831
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965796
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965759
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965725
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965688
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965664
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965632
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965600
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965569
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965538
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965513
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965481
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965445
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965418
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965404
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965375
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965357
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965340
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965315
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965292
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965265
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965244
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965213
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965182
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965160
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965129
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965092
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965051
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965018
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=964981
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=964950
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=964914
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=964878
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=964843
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=964814
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=964784
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=964755
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=964729
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=964707
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=964680
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=964653
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=964621
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=964582
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=964548
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=964507
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=964452
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=964406
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=964365
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=964322
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=964278
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=964234
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=964189
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=964151
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=964119
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=964073
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=964026
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=964003
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963976
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963954
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963930
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963909
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963882
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963862
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963847
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963838
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963633
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963610
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963593
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963572
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963553
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963542
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963505
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963487
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963465
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963446
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963428
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963408
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963391
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963380
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963373
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963363
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963357
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963349
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963340
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963332
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963324
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963315
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963306
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963298
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963292
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963284
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963277
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963268
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963238
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963222
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963202
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963183
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963165
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963148
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963136
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963119
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963103
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963083
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963064
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963051
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963038
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963021
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=963005
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962990
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962971
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962957
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962943
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962930
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962907
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962896
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962881
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962862
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962853
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962716
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962707
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962694
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962680
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962671
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962660
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962649
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962622
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962610
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962598
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962591
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962581
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962570
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962558
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962550
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962548
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962546
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962544
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962542
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962540
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962538
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962536
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=962535
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=969414
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=969389
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=969359
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=969334
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=969315
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=969294
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=969278
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=969244
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=969221
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=969159
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=969125
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=969067
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=969021
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968947
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968907
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968879
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968849
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968800
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968769
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968731
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968699
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968657
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968630
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968594
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968549
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968510
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968474
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968443
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968398
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968357
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968330
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968282
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968251
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968214
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968182
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968160
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968133
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968101
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968067
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=968029
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967998
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967973
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967936
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967897
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967861
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967831
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967794
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967758
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967725
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967685
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967646
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967585
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967419
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967318
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967207
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967144
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=967098
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=966959
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=966929
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=966819
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=966397
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=966361
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=966306
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=966265
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=966224
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=966187
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=966161
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=966122
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=966028
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=966001
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965962
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965933
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965898
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965871
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965835
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965795
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965756
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965728
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965695
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965669
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965633
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965598
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965563
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965532
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965501
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965470
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965442
http://pic.cnhubei.com/space.php?uid=2732&do=album&id=965415