DBMS Tutorial Point
Database-management-system Tutorial .
Group by and Having clause in SQL:- Group by and Having clauses in SQL is a very important topic of SQL. USE OF HAVING Clause HAVING clause: It is designed to be used with GROUP BY So that it can restrict the groups that appear in the final result table.Example: For each branch office with … Read more
A subquery is a query within a query for the same or different table. The inner query is enclosed in parentheses (). The result of the inner query would be given as input to the outer query. Subqueries enable you to write queries that select data rows for criteria that are actually developed while the … Read more
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