下列语句错误的是() A: select*fromorderswhereordernameisnotnull; B: select*fromorderswhereordername<>null; C: select*fromorderswhereordernameisnull; D: select*fromorderswhereordernamenotisnull;
下列语句错误的是() A: select*fromorderswhereordernameisnotnull; B: select*fromorderswhereordername<>null; C: select*fromorderswhereordernameisnull; D: select*fromorderswhereordernamenotisnull;
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