题目内容
删除成绩表中的CHECK约束,sql实现语言是: ALTER 成绩DROP CONSTRAINT ck_cj
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用户定义完整性约束有以下几种:NOT NULL、CHECK、DEFAULT和 UNIQUE等约束。
[音频]Everyone needs friendship. No one can sail the ocean of life single-handed. We need help from, and also give help to, others. In the modern age, people ______ more importance to relations and connections. A man of charisma has many friends. His power lies in his ability to give.
[音频]The term, friend, ______ a wide range of meanings. It can be a nodding acquaintance, a comrade, a confidant, a partner, a playmate, a brother, an ________, etc. As life is full of strife and ________, we need friends to support and help us out of difficulties.
[音频]Our friends give us _________ against danger. True friends share not only joy but, more often than not, they share ______. With friendship, life is happy and ___________. Without friendship, life is hostile and unfortunate.
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