CBSE Assignment for Class XII Informatics Practices -MYSQL Revision Tour . Based on CBSE and CCE guidelines. The students should read these basic concepts to gain perfection which will help him to get more marks in CBSE examination.
MYSQL REVISION TOUR
1. What do you mean by a Database Management System?
Ans- Database Management is a collection of programs and files that allow a user to define structure of a database, store data into it, modify the structure and manipulate the data.
2. What do you mean by Relational database?
Ans-Relational Database is a type of database in which relation is used as its basic element.Row and columns are used to store data.
3. What is a foreign key?
Ans If a key is available in a table as a primary key then this key is called foreign key in another table.
4. What is primary key?
Ans-Primary key is a unique key in a relation which can uniquely identifies a tuple (row) in a given relation.
5. What is SQL?
Ans-SQL is stands for structured query language. This language is used to manipulate data stored in a table.
6. What is referential integrity?
Ans-This is a rule which ensures that in DBMS relationships between records in related tables are valid. And that user don’t accidently delete or change related data.
7. What is MySql?
Ans-Mysql is an open source RDBMS which uses SQL.
8. What is DDL?
Ans- DDL provides commands to define or redefine the schema of a table.Table is created,altered and dropped using DDL.
9. What are DML commands?
Ans- DML commands are used to manipulate data stored in a table.Insertion, deletion and modifications are possible using DML commands.
10. Maximum how many characters can be stored in a (i) text literals (ii) numeric literal
Ans-(i) Text literals can have 4000 bytes (ii) A numeric literals can store 53 digits.
11. What is null value in MySql?
Ans-If a column in a row has no value, then column is said to be null.
12. Which keyword eliminates redundant data in from a query result?
13. How would you display system date as the result of a query?
14. What is NOW() function in MySql?
Ans- It returns the current date and time.
15. What is NOT NULL constraint?
Ans- NOT NULL constraints impose a condition that value of a row cannot be left blank.
16. What is error in following statement? UPDATE EMPL;
Ans- WHERE clause is missing in given query.
17. Identify the error? DELETE ALL FROM TABLE EMP;
Ans-There is no need to write ALL and TABLE word in above query. Correct form is-DELETE FROM EMP;
18. Differeniate WHERE and HAVING clause?
Ans-:- Where clause is used to select particular rows that satisfy condition whereas having clause is used in connection with aggregate function, group by clause.
Please refer to attached file for CBSE Class 12 Informatics Practices MYSQL Revision Tour