【单选题】What is the candidate key of a relational database? ( )
A.
Fields from multiple tables that are used for sorting records
B.
A set of fields in a table used to identify a record uniquely
C.
A field with a constraint placed on it
D.
A set of fields that have no data in them
【简答题】combine the sentences in each of the following groups into one, using parallel constructions wherever possible. A Black people in America have been neglected for years B Black people in America have b...
【单选题】流清涕和鼻黏膜肿胀,无明确的吸入过敏原,有个人过敏性疾病史,变应原皮肤试验两项阳性,特异性IgE抗体检测阴性,鼻分泌物涂片检查嗜酸性粒细胞阴性。该患者的诊断是
【单选题】Customer relationship management systems typically provide software and online tools for sales, customer service, and
【单选题】What did the expansion of fields in the First World War lead to?
D.
Extinction of rattlesnakes.
【单选题】Which of the following is a logical connected set of fields that describes a person, place or a thing?
【简答题】A Black people in America have been neglected for years B Black people in America have been underestimated for years C. Their recent accomplishments in a variety of fields have made "black power"real。...
【单选题】思科路由器上全局配置模式的提示符是什么?
【判断题】A bunch of fields form a record