Define subschema. subschema synonyms, subschema pronunciation, subschema translation, English dictionary definition of subschema. n a part of a computer database which is used by an individual Collins English Dictionary – Complete and Unabridged, 12th E
1、这是Schema的definition: A schema is a collection of database objects (used by a user.) Schema objects are the logical structures that directly refer to the database’s data. A user is a name defined in the database that can connect to and access objects. Schemas and users help data...
These can be used in database migrations to define database schema types using a PHP interface. This is useful to define a schema in a DBMS independent way so that the application may run on different DBMS the same way.For example you may use the following code inside your migration files...
Once the logical schema is determined, if not before, the target DBMS is selected. The physical schema can then be generated for this specific platform. Some aspects of tuning the physical model to improve performance are covered later in Chapter 14 (e.g., index selection and denormalization)...
A key component of a DBMS is the data, which contains information about the structure of the database. For each data element stores in the database, such as the customer number, there is a corresponding record in the data dictionary describing ...
is the structure of adatabasesystem, described in a formal language supported by thedatabase management system (DBMS). In arelational database, the schema defines thetables, thefieldsin each table, and the relationships between fields and tables. ...
数据库本身不方便直接操作,数据厂商将数据库封装成一个系统(软件),该软件可以提供便捷的操作内部数据库的方式,这种软件叫DBMS。 数据库(DB):按照一定结构组织的数据集合,由存储数据的文件组成。 数据库管理系统(DBMS):管理软件。 2)数据库分类: 关系型数据库(RDB:Relationship DataBase):创建在关系模型上的数据库...
选择“share the DBMS definition”然后点击确定。注意,数据库也要选择和自己的数据库对应的,我的数据库是mysql5.0的,所有我也选择了mysql5.0。 选“Using script files”,点左侧的添加按钮,讲test.sql文件添加,然后选择确定。这样,mysql数据表结构就完全导入了powerdesigner里。
Column size or precision definition. This parameter will be ignored if not supported by the DBMS. return yii\db\ColumnSchemaBuilder The column instance which can be further customized. string() 公共 方法 (自版本 2.0.6 可用) Creates a string column. public yii\db\ColumnSchemaBuilder string($...
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