DBMS Tutorial Point
1-A Database Management System (DBMS) is A. Collection of interrelated data B. Collection of programs to access data C. Collection of data describing one particular enterprise D. All of the above 2. Which of the following is not a level of data abstraction? A. Physical Level B. Critical Level C. Logical Level D. View Level 3. Disadvantages of File … Read more
The UNIQUE constraint uniquely identifies each row in a table. The restriction which unique enforces in the Uniqueness of values with respect to any column. The UNIQUE and PRIMARY KEY constraints both provide a guarantee for uniqueness for a column or set of columns. A PRIMARY KEY automatically has a UNIQUE key defined on it. … Read more
A primary key in SQL is a one-column or combination of the column with a unique value for each row or tuple. The value of the primary key must be unique within the table. The purpose is to bind data together, across tables, without repeating all of the data in every table. It enforces two … Read more
Integrity constraints in DBMS Integrity in data means maintaining and assuring the accuracy and consistency of data over its entire life cycle. Database Systems ensure data integrity through Integrity Constraints in DBMS that are used to restrict data that can be entered or modified in the database. Constraints are used to limit the type of … Read more