Ans: DBMS stands for Database Management System. A DBMS receives requests from applications and translates those requests into actions on a specific database.
A DBMS processes SQL statements or uses other functionality to create, process and administer databases.
Ans: The database and DBMS software together is called as Database system.
Ans: When database are inserted, deleted or updated, a procedure is executed in response to that action. Such SQL procedure are called as trigger.
Ans: Data independence means that ?the application is independent of the storage structure and access strategy of data?. In other words, The ability to modify the schema definition in one level should not affect the schema definition in the next higher level.
Ans: Sub-Query is also called as Nested Query. Sub-Query is a query within another query. Sub-Query can be used with SELECT, INSERT, UPDATE and DELETE Statement.
Ans: Data is recorded facts and figures, and information is knowledge derived from data. A database stores data in such a way that information can be created.
Ans: Normalization is process of organizing database. Normalization process usually involves removing or eliminating redundancy data from fields and tables of relational database.
Ans: It is a 'thing' in the real world with an independent existence.
Ans: The advantages of DBMS are as follows:
Ans: A view may be thought of as a virtual table, that is, a table that does not really exist in its own right but is instead derived from one or more underlying base table. In other words, there is no stored file that direct represents the view instead a definition of view is stored in data dictionary.
Growth and restructuring of base tables is not reflected in views. Thus the view can insulate users from the effects of restructuring and growth in the database. Hence accounts for logical data independence. .
Ans: In addition to the users' data, a database contains a description of its own structure. This descriptive data is called "metadata."
Ans: It is a process of analysing the given relation schemas based on their Functional Dependencies (FDs) and primary key to achieve the properties
Ans: A collection of conceptual tools for describing data, data relationships data semantics and constraints.
Ans: There are different types of Normalization. They are: First Normal Form(1NF), Second Normal Form(2NF), Third Normal Form(3NF), Fourth Normal Form(4NF) and Boyce-Codd Normal Form (BCNF)
Ans: SQL stands for Structured Query Language, and is the most important data processing language in use today. It is not a complete programming language like Java or C#, but a data sublanguage used for creating and processing database data and metadata. All DBMS products today use SQL.
Ans: NOT NULL, UNIQUE, PRIMARY KEY, FOREIGN KEY, CHECK and DEFAULT are some of constraints.
Ans: This data model is based on real world that consists of basic objects called entities and of relationship among these objects. Entities are described in a database by a set of attributes.
Ans: Constraint in database set certain rules or property in a table. Suppose if a row has NOT NULL constraint, then it cannot have any null values.
Ans: SELECT * FROM STUDENT WHERE Grade >= 90;
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Ans: This model is based on collection of objects. An object contains values stored in instance variables with in the object. An object also contains bodies of code that operate on the object. These bodies of code are called methods. Objects that contain same types of values and the same methods are grouped together into classes.
Ans: Index is used for faster retrieval of information store and speedup query performance. There are two types of index, clustered index and non-clustered index.
Ans: DBMS provides a systematic and organized way of storing, managing and retrieving from collection of logically related information. RDBMS also provides what DBMS provides but above that it provides relationship integrity.
Ans: Aggregate functions are used to evaluate mathematical calculation and return single values. This can be calculated from the columns in a table. Scalar functions return a single value based on the input value.
Example:Aggregate – max(), count – Calculated with respect to numeric.
Scalar – UCASE(), NOW() – Calculated with respect to strings.
Ans: MINUS operator is used to return rows from the first query but not from the second query. INTERSECT operator is used to return rows returned by both the queries.
Ans: Database can be created by ‘CREATE DATABASE’ Statements. For Example: CREATE DATABASE dbname;
Ans: It is a particular property, which describes the entity.
Ans: Collation is defined as set of rules that determine how character data can be sorted and compared. This can be used to compare A and, other language characters and also depends on the width of the characters.
ASCII value can be used to compare these character data.
Ans: This language that enable user to access or manipulate data as organised by appropriate data model.
Ans: SQL join are used for retrieving information and data from two or more tables. SQL Join combine two or more table(or row).
Ans: A stored procedure is a named group of SQL statements that have been previously created and stored in the server database.
Ans: Cross join defines as Cartesian product where number of rows in the first table multiplied by number of rows in the second table. If suppose, WHERE clause is used in cross join then the query will work like an INNER JOIN.
Ans: It translates DML statements in a query language into low-level instruction that the query evaluation engine can understand.
Ans: For creating a Table in database, we have to use ‘CREATE TABLE’ Statement.
For Example:
CREATE TABLE “SomeName”
(“col1” “datatype”,
(“col2” “datatype”);
Ans: A database Cursor is a control which enables traversal over the rows or records in the table. This can be viewed as a pointer to one row in a set of rows. Cursor is very much useful for traversing such as retrieval, addition and removal of database records.