Read and download free pdf of CBSE Class 12 Computer Science Dbms And Structured Query Language Worksheet. Students and teachers of Class 12 Computer Science can get free printable Worksheets for Class 12 Computer Science in PDF format prepared as per the latest syllabus and examination pattern in your schools. Standard 12 students should practice questions and answers given here for Computer Science in Grade 12 which will help them to improve your knowledge of all important chapters and its topics. Students should also download free pdf of Class 12 Computer Science Worksheets prepared by school teachers as per the latest NCERT, CBSE, KVS books and syllabus issued this academic year and solve important problems provided here with solutions on daily basis to get more score in school exams and tests
CBSE Class 12 Computer Science DBMS and Structured Query Language. CBSE issues sample papers every year for students for class 12 board exams. Students should solve the CBSE issued sample papers to understand the pattern of the question paper which will come in class 12 board exams this year. The sample papers have been provided with marking scheme. It’s always recommended to practice as many CBSE sample papers as possible before the board examinations. Sample papers should be always practiced in examination condition at home or school and the student should show the answers to teachers for checking or compare with the answers provided. Students can download the sample papers in pdf format free and score better marks in examinations. Refer to other links too for latest sample papers.
• Basic Database concepts
Data : Raw facts and figures which are useful to an organization. We cannot take decisions on the basis of data.
Information: Well processed data is called information. We can take decisions on the basis of information Field: Set of characters that represents specific data element.
Record: Collection of fields is called a record. A record can have fields of different data types.
File: Collection of similar types of records is called a file.
Table: Collection of rows and columns that contains useful data/information is called a table. A table generally refers to the passive entity which is kept in secondary storage device.
Database: Collection of logically related data along with its description is termed as database.
Relation: Relation (collection of rows and columns) generally refers to an active entity on which we can perform various operations. It is also known as table.
Tuple: A row in a relation is called a tuple. It is also known as record.
Attribute: A column in a relation is called an attribute. It is also termed as field or data item.
Degree: Number of attributes in a relation is called degree of a relation.
Cardinality: Number of tuples in a relation is called cardinality of a relation.
Primary Key: Primary key is a key that can uniquely identifies the records/tuples in a relation. This key can never be duplicated and NULL.
Foreign Key: Non key attribute of a table acting as primary key in some other table is known as Foreign Key in its current table. This key is used to enforce referential integrity in RDBMS.
Candidate Key: Attributes of a table which can serve as a primary key are called candidate keys.
Alternate Key: All the candidate keys other than the primary key of a relation are alternate keys for a relation.
DBA: Data Base Administrator is a person (manager) that is responsible for defining the data base schema, setting security features in database, ensuring proper functioning of the data bases etc.
Select Operation: The select operation selects tuples from a relation which satisfy a given condition.
It is denoted by lowercase Greek Letter σ (sigma).
Project Operation:The project operation selects columns from a relation which satisfy a given condition. It is denoted by lowercase Greek Letter π (pi). It can be thought of as picking a sub set of all available columns.
Union Operation: The union (denoted as ∪) of a collection of relations is the set of all distinct tuples in the collection. It is a binary operation that needs two relations.
Set Difference Operation: This is denoted by – (minus) and is a binary operation. It results in a set of tuples that are in one relation but not in another
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