【数据库系统工程师201905】【71-75】The entity-relationship (E-R) data model is based on a perception of a real world that consists of a collection of basic objects, called （71），and of relationships among these objects. An entity is a “thing” or “object” in the real world that is distinguishable from other objects. Entities are described in a database by a set of （72） . A relationship is an association among several entities. The set of all entities of the same type and the set of all relationships of the same type are termed an entity set and relationship set, respectively. The overall logical structure (schema) of a database can be expressed graphically by an E-R diagram, which is built up from the following components: （73） represent entity set, （74） represent attributes, etc. In addition to entities and relations, the E-R model represents certain（75） to which the contents of a database must conform. The entity-relationship model is widely used in database design.

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【数据库系统工程师201905】【71-75】The entity-relationship (E-R) data model is based on a perception of a real world that consists of a collection of basic objects, called （71），and of relationships among these objects. An entity is a “thing” or “object” in the real world that is distinguishable from other objects. Entities are described in a database by a set of （72） . A relationship is an association among several entities. The set of all entities of the same type and the set of all relationships of the same type are termed an entity set and relationship set, respectively. The overall logical structure (schema) of a database can be expressed graphically by an E-R diagram, which is built up from the following components: （73） represent entity set, （74） represent attributes, etc. In addition to entities and relations, the E-R model represents certain（75） to which the contents of a database must conform. The entity-relationship model is widely used in database design.

真题详情及解析

【数据库系统工程师201905】【71-75】The entity-relationship (E-R) data model is based on a perception of a real world that consists of a collection of basic objects, called （71），and of relationships among these objects. An entity is a “thing” or “object” in the real world that is distinguishable from other objects. Entities are described in a database by a set of （72） . A relationship is an association among several entities. The set of all entities of the same type and the set of all relationships of the same type are termed an entity set and relationship set, respectively. The overall logical structure (schema) of a database can be expressed graphically by an E-R diagram, which is built up from the following components: （73） represent entity set, （74） represent attributes, etc. In addition to entities and relations, the E-R model represents certain（75） to which the contents of a database must conform. The entity-relationship model is widely used in database design.

真题详情及解析

【数据库系统工程师201905】【71-75】The entity-relationship (E-R) data model is based on a perception of a real world that consists of a collection of basic objects, called （71），and of relationships among these objects. An entity is a “thing” or “object” in the real world that is distinguishable from other objects. Entities are described in a database by a set of （72） . A relationship is an association among several entities. The set of all entities of the same type and the set of all relationships of the same type are termed an entity set and relationship set, respectively. The overall logical structure (schema) of a database can be expressed graphically by an E-R diagram, which is built up from the following components: （73） represent entity set, （74） represent attributes, etc. In addition to entities and relations, the E-R model represents certain（75） to which the contents of a database must conform. The entity-relationship model is widely used in database design.

真题详情及解析

【数据库系统工程师201905】【71-75】The entity-relationship (E-R) data model is based on a perception of a real world that consists of a collection of basic objects, called （71），and of relationships among these objects. An entity is a “thing” or “object” in the real world that is distinguishable from other objects. Entities are described in a database by a set of （72） . A relationship is an association among several entities. The set of all entities of the same type and the set of all relationships of the same type are termed an entity set and relationship set, respectively. The overall logical structure (schema) of a database can be expressed graphically by an E-R diagram, which is built up from the following components: （73） represent entity set, （74） represent attributes, etc. In addition to entities and relations, the E-R model represents certain（75） to which the contents of a database must conform. The entity-relationship model is widely used in database design.

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【数据库系统工程师201905】【70】以下关于NoSQL数据库的说法中，正确的是（70）。

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【数据库系统工程师201905】【69】（69）不是目前NoSQL数据库产品的数据模型。

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【数据库系统工程师201905】【68】以下关于大数据的叙述中，错误的是（68）。

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【数据库系统工程师201905】【67】以下有关数据库审计的叙述中，错误的是（67）。

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【数据库系统工程师201905】【65-66】在数据库系统运行中，经常会找出频繁执行的SQL语句进行优化。常见的优化策略有：尽可能减少多表查询或建立（65）；用带（66）的条件子句等价替换OR子句；只检索需要的属性列等。

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