Arelation(from the relational database model)consistsof(由⋯⋯组成)a set of tuples(元组),whichimplies(意味着)that().

A．all tuples in a relation must be distinct(独一无二的)

B．every relation has a key(键)

C．all of the above

D．for any two tuples,the values associated with one or more of thei rattributes(属性)must differ

[单选题]The relational database model requires the data be(71)through programs that don't rely on the position of the data in the database. This is in direct(72)to the other database mode, where the program has to follow a series of pointers to the data it

[单选题]( ) is a query language for manipulating data in a relational database.A.As

[单选题]Every value in arelation must be().A．composite(复合的)and single-valuedB．single-valuedC．notnull and single-valuedD．simple and single-valued

[单选题]Relational Model表示（）。A . 关系模型B . 数据结构C . 网络D . 实体

[单选题]SQL Server is a RDBMS(Relational Database Management System)made by Microsoft.This means that the data is stored in two dimensional (74) .(74) A．documentsB．databasesC．filesD．tables

[单选题]SQL Server is a RDBMS(Relational Database Management System)made by Microsoft. This means that the data is stored in two dimensional(70)。A．documentsB．databasesC．filesD．tables

[单选题]If the weights are moved away from the midship section，（）will happen on board.A . hoggingB . saggingC . stiffD . tender

[主观题]C．ompanies from western countries value modest and humble employees as equally as businesses in the far-eastern areas do.()

[单选题]6．—______?—I’m from Beijing．A． Are you from BeijingB． Do you come from BeijingC． Where are you fromD． When are you from

[单选题]In developing a hospital database, it is determined that on the average, each patient will have 6 treatments during a hospital stay.The average length of a stay is three days.The hospital has 1000 beds.There are on the average 800 patients occupying