This is the physical level of information. The actual structure of the table and data are stored in the server’s memory. Columns, their data types, their mapping, and constraints like primary key, foreign key information are the logical level of information. In a STUDENT table example, records of each student which user sees are view level of information. This level of abstraction is called a view level. They will not have any information about how they are stored, what kind of datatype it has, how many records it has etc. Either they will see whole data values or any specific records. The user will get to see only the data stored in the database. The developer and the DBA will have knowledge about this data. These are all called logical levels of data. This information defines the structure of the objects in the database. The information like table/view names, their columns, indexes, and constraints on them, the mapping between the tables are all next level of information related to the database. This is called the physical level of data. This kind of information is called physical storage information and is usually the lowest level of information. This information is usually the basic storage information of any computer. Let us see all of themĮach data value and structure details of the database objects are stored in magnetic tapes, magnetic disks, optical disks, etc. All these information are different from each other in their own way. There are exact values for each record that are shown to the user. There is basic information about the objects like their names, columns in them, a total number of records, their indexes, and constraints, the mapping between the tables, functions/procedures used in packages, etc. There is storage information about the data, object structure. But actual structure and data are stored in different ways. what we see on the monitor is the user-friendly display of the data. But they all differ from what we see on the monitor. They have their specifications, tasks, and value in the database. The database consists of different objects like schema, tables, views, constants, cursors, procedures, functions, packages, synonyms, etc.
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