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查询city列的值为空的记录，在where子句中的条件应写为（）。
- A、ity=null
- B、city='null'
- C、city is null
- D、city is 'null'
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单选题查询city列的值为空的记录，在where子句中的条件应写为（）。A
ity=nullB
city='null'C
city is nullD
city is 'null'
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