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Database Articles
Page 128 of 547
Explain the role of the Database Administrator in DBMS?
A database administrator (DBA) is a person or group in charge of implementing DBMS in an organization. The DBA job requires a high degree of technical expertise. DBA consists of a team of people rather than just one person.The primary role of Database administrator is as follows −Database designPerformance issuesDatabase accessibilityCapacity issuesData replicationTable MaintenanceResponsibilities of DBAThe responsibilities of DBA are as follows −Makes the decision concerning the content of the database.Plans the storage structure and access strategy.Provides the support to the users.Defines the security and integrity checks.Interpreter backup and recovery strategies.Monitoring the performance and responding to the changes in the ...
Read MoreFix ERROR 1064 (42000) while creating a database in MySQL?
The ERROR 1064 (42000) mainly occurs when the syntax isn’t set correctly i.e. error in applying the backtick symbol or while creating a database without them can also create an error, if you will use hyphen in the name, for example, Demo-Table will result in ERROR 1064 (42000).To remove the error, you need to use backtick around the database name properly or use nothing. Following is the syntax wherein we haven’t used the backtick. This works correctly −create database yourDatabaseName;Since adding hyhen to the database name will result in an error. Let us implement it while creating the database name ...
Read MoreWhat are the functionalities of data mining?
Data mining functionalities are used to represent the type of patterns that have to be discovered in data mining tasks. In general, data mining tasks can be classified into two types including descriptive and predictive. Descriptive mining tasks define the common features of the data in the database and the predictive mining tasks act inference on the current information to develop predictions.There are various data mining functionalities which are as follows −Data characterization − It is a summarization of the general characteristics of an object class of data. The data corresponding to the user-specified class is generally collected by a ...
Read MoreThree Level Architecture of Database
The ANSI-SPARC database architecture is the basis of most of the modern databases.The three levels present in this architecture are Physical level, Conceptual level and External level.The details of these levels are as follows −Physical LevelThis is the lowest level in the three level architecture. It is also known as the internal level. The physical level describes how data is actually stored in the database. In the lowest level, this data is stored in the external hard drives in the form of bits and at a little high level, it can be said that the data is stored in files ...
Read MoreWhat is data Abstraction in DBMS?
Data Abstraction is a process of hiding unwanted or irrelevant details from the end user. It provides a different view and helps in achieving data independence which is used to enhance the security of data.The database systems consist of complicated data structures and relations. For users to access the data easily, these complications are kept hidden, and only the relevant part of the database is made accessible to the users through data abstraction.Levels of abstraction for DBMSDatabase systems include complex data-structures. In terms of retrieval of data, reduce complexity in terms of usability of users and in order to make ...
Read MoreSubclasses, Superclasses, and Inheritance
The Enhanced Entity Relationship Model contains all the features of the Entity Relationship model. In addition to all that, it also contains features of Subclasses, Superclasses and Inheritance.All of these in detail are as follows −SubclassesA subclass is a class derived from the superclass. It inherits the properties of the superclass and also contains attributes of its own. An example is:Car, Truck and Motorcycle are all subclasses of the superclass Vehicle. They all inherit common attributes from vehicle such as speed, colour etc. while they have different attributes also i.e Number of wheels in Car is 4 while in Motorcycle ...
Read MoreSQL Query to Convert Rows to Columns in SQL Server
Introduction The PIVOT operator is used to rotate rows of a table into columns. It is useful for generating cross-tabular reports, where the results are presented in a summary form. The PIVOT operator is available in SQL Server 2005 and later versions. The PIVOT operator is used to convert rows into columns in a SQL Server database. It is often used to generate cross-tabular reports, where the results are presented in a summary form. Definition In SQL Server, the PIVOT operator allows you to convert rows into columns. It is useful for generating cross-tabular reports, where the results are ...
Read MoreWhat does it mean by select 1 from MySQL table?
The statement select 1 from any table name means that it returns only 1. For example, If any table has 4 records then it will return 1 four times. Let us see an example. Firstly, we will create a table using the CREATE command. mysql> create table StudentTable -> ( -> id int, -> name varchar(100) -> ); Query OK, 0 rows affected (0.51 sec) Inserting records mysql> insert into StudentTable values(1, 'John'), (2, 'Carol'), (3, 'Smith'), (4, 'Bob'); Query OK, 4 rows affected (0.21 ...
Read MoreExplain the characteristics of DBMS?
There are so many characteristics of a database management system, which are as follows − A database management system is able to store any kind of data in a database. The database management system has to support ACID (atomicity, consistency, isolation, durability) properties. The Database management system allows so many users to access databases at the same time. Backup and recovery are ...
Read MoreSELECT where row value contains string in MySQL?
To select the row value containing string in MySQL, use the following syntax.SELECT *FROM yourTableName where yourColumnName like ‘%yourPattern%’;To understand the above syntax, let us first create a table. The query to create a table is as follows.mysql> create table PatternDemo -> ( -> Id int, -> Name varchar(100), -> Age int -> ); Query OK, 0 rows affected (0.97 sec)Insert records in the table using insert command. The query is as follows.mysql> insert into PatternDemo values(1, 'James', 23); Query OK, 1 row affected (0.11 sec) mysql> insert into PatternDemo values(2, 'Joseph', 21); Query OK, 1 row affected (0.18 ...
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