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Showing posts from February, 2024

Enter records (insert into-select)

A record is a row in the table that contains the data itself. Each record has one data for each column (field). Our "users" table consists of 2 fields, "name" and "password". When entering the data for each record, the quantity and order of the fields must be taken into account. The basic and general syntax is as follows:  insert into TABLENAME (FIELDNAME1, ..., FIELDNAMEn)values ​​(FIELD VALUE1, ..., FIELD VALUEn); We use "insert into", then the name of the table, we detail the names of the fields between parentheses and separated by commas and after the "values" clause we place the values ​​for each field, also between parentheses and separated by commas. In the following example a record is added to the "users" table, in the "name" field "Mariano" will be stored and "clown" will be stored in the "password" field:  insert into users (name, password)  values ​​('Mariano', 'c

Relational Model in DBMS

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  Relational Model (RM) represents the database as a collection of relationships. A relationship is nothing more than a table of values. Each row of the table represents a collection of related data values. These rows of the table denote a real-world entity or relationship. The table name and column names are useful for interpreting the meaning of the values in each row. Data are represented as a set of relationships. In the relational model, the data are stored as tables. However, the physical storage of data is independent of how data is organized logically. Some popular relational database management systems are: DB2 and Informix Dynamic Server – IBM Oracle and RDB – Oracle SQL Server and Access – Microsoft Concepts of relational model in DBMS Attribute: Each column in a table. Attributes are the properties that define a relationship. e.g. Student_Rollno, NAME, etc. Tables – In the Relational model the relationships are saved in table format. It is s