关系数据库-------外文参考文献翻译.doc
约13页DOC格式手机打开展开
关系数据库-------外文参考文献翻译,1.1 关系术语一个二维表就是一关系。常用的关系术语如下：记录：二维表中每一行称一个记录，或称为一元组。字段：二维表中每一列称为一个字段，或称为一个属性。域：即属性的取值范围。例如，在考试成绩关系中，“数学”字段的域为0～100。在学生关系中，“性别”字段的域是“男”和“女”。关键字：在一个关系中有这样一个或几个字段，...
内容介绍
此文档由会员 wanli1988go 发布
1.1 关系术语
一个二维表就是一关系。常用的关系术语如下：
记录：二维表中每一行称一个记录，或称为一元组。
字段：二维表中每一列称为一个字段，或称为一个属性。
域：即属性的取值范围。例如，在考试成绩关系中，“数学”字段的域为0～100。在学生关系中，“性别”字段的域是“男”和“女”。
关键字：在一个关系中有这样一个或几个字段，它的值可以惟一地标识一条记录，称之为关键字（Key）。
关系模式：对关系的描述称为关系模式，其格式为：
关系名（属性名1，属性名2，…，属性名n）
一个关系模式对应关系的结构，它的命名的属性集合。
1.2数据独立性
Relate to the technical term
A two the watch of be a relation. In common use relation technical term is as follows:
Record: Two form inside each lines call a record, or call a dollar set.
Word segment: Two form inside each rows call a word segment, or call a belongs to the sex.
Area:Belong to namely to take the worth scope sexually.For example, in examine score relation, the area of the " mathematics" word segment is 0 ～ 100.In student relate to, the area of the " sex" word segment is a " male" with the " woman".
Key word:There is like this a value for or a few words segment, it in a relation can only one marking a record, call it as the key word.( Key)
Relate to the mode:To relate to of describe to call to relate to the mode, its format is:
Relate to( belong to sex 1, belong to sex 2, … , belong to the sex a n)
A relation mode to the construction that should relate to, it assign name to of belong to the sex gather.
Data independent
Database system to 1:00 of the pass importance is application that database should independence in whichever in a specific way.The traditional data handles the application is a data related.The COBOL language procedure includes the detailed describing the data format to explain with record the elucidation with the document of the characteristic.
The customer is at the request of can change database constructio
一个二维表就是一关系。常用的关系术语如下：
记录：二维表中每一行称一个记录，或称为一元组。
字段：二维表中每一列称为一个字段，或称为一个属性。
域：即属性的取值范围。例如，在考试成绩关系中，“数学”字段的域为0～100。在学生关系中，“性别”字段的域是“男”和“女”。
关键字：在一个关系中有这样一个或几个字段，它的值可以惟一地标识一条记录，称之为关键字（Key）。
关系模式：对关系的描述称为关系模式，其格式为：
关系名（属性名1，属性名2，…，属性名n）
一个关系模式对应关系的结构，它的命名的属性集合。
1.2数据独立性
Relate to the technical term
A two the watch of be a relation. In common use relation technical term is as follows:
Record: Two form inside each lines call a record, or call a dollar set.
Word segment: Two form inside each rows call a word segment, or call a belongs to the sex.
Area:Belong to namely to take the worth scope sexually.For example, in examine score relation, the area of the " mathematics" word segment is 0 ～ 100.In student relate to, the area of the " sex" word segment is a " male" with the " woman".
Key word:There is like this a value for or a few words segment, it in a relation can only one marking a record, call it as the key word.( Key)
Relate to the mode:To relate to of describe to call to relate to the mode, its format is:
Relate to( belong to sex 1, belong to sex 2, … , belong to the sex a n)
A relation mode to the construction that should relate to, it assign name to of belong to the sex gather.
Data independent
Database system to 1:00 of the pass importance is application that database should independence in whichever in a specific way.The traditional data handles the application is a data related.The COBOL language procedure includes the detailed describing the data format to explain with record the elucidation with the document of the characteristic.
The customer is at the request of can change database constructio
