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在关系中，"基数"（Cardinality）是指（）
- A、行数
- B、属性个数
- C、关系个数
- D、列数
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更多 “在关系中，"基数"（Cardinality）是指（）A、行数B、属性个数C、关系个数D、列数” 相关考题
考题
下面对cardinality的最佳描述是：（）A、在geodatabase中空间数据和属性数据之间的联合B、描述相互关联的两种类型的数量或对象之间的关系C、在一个连接中，主键字段和名称字段之间的联系D、在geodatabase中，用来描述不同主键值数量的表的属性
考题
Examine the parameters for your database instance: Which three statements are true about the process of automatic optimization by using cardinality feedback?（）A、The optimizer automatically changes a plan during subsequent execution of a SQL statement if there is a huge difference in optimizer estimates and execution statistics.B、The optimizer can re optimize a query only once using cardinality feedback.C、The optimizer enables monitoring for cardinality feedback after the first execution of a query.D、The optimizer does not monitor cardinality feedback if dynamic sampling and multicolumn statistics are enabled.E、After the optimizer identifies a query as a re-optimization candidate, statistics collected by thecollectors are submitted to the optimizer.
考题
单选题阶梯式计量水价中的第二级水量基数是指（ ）。A
确保居民基本生活用水的水量基数B
根据改善和提高居民生活质量的原则制定的水量基数C
满足特殊需要的水量基数D
用于保护环境的水量基数
考题
多选题Examine the parameters for your database instance: Which three statements are true about the process of automatic optimization by using cardinality feedback?（）AThe optimizer automatically changes a plan during subsequent execution of a SQL statement if there is a huge difference in optimizer estimates and execution statistics.BThe optimizer can re optimize a query only once using cardinality feedback.CThe optimizer enables monitoring for cardinality feedback after the first execution of a query.DThe optimizer does not monitor cardinality feedback if dynamic sampling and multicolumn statistics are enabled.EAfter the optimizer identifies a query as a re-optimization candidate, statistics collected by thecollectors are submitted to the optimizer.
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