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Database Articles
Page 282 of 547
How can we upload data into multiple MySQL tables by using mysqlimport?
With the help of mysqlimport we can upload data into multiple MySQL tables. It is illustrated in the example below −ExampleSuppose we want to upload the following data from two data files namely student1_tbl.txt −1 Saurav 11th 2 Sahil 11th 3 Digvijay 11thAnd House.txt1 Furniture 2 Television 3 RefrigeratorFollowings are MySQL tables into which we want to upload the above data −mysql> DESCRIBE Student1_tbl; +--------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------+-------------+------+-----+---------+-------+ | RollNo | int(11) ...
Read MoreIn what cases, we cannot use MySQL TRIM() function?
Actually for using MySQL TRIM() function we must have to know the string which we want to trim from the original string. This becomes the major drawback of TRIM() in the cases where we want to trim the strings having different values. For example, suppose we want to get the output after trimming the last two characters from the strings but every string is having different characters at last two places.Examplemysql> Select * from Employee; +------+----------------+------------+-----------------+ | Id | Name | Address | Department | +------+----------------+------------+-----------------+ | 100 | Raman ...
Read MoreSecurity, Integrity and Authorization in DBMS
Database SecurityDatabase security has many different layers, but the key aspects are:AuthenticationUser authentication is to make sure that the person accessing the database is who he claims to be. Authentication can be done at the operating system level or even the database level itself. Many authentication systems such as retina scanners or bio-metrics are used to make sure unauthorized people cannot access the database.AuthorizationAuthorization is a privilege provided by the Database Administer. Users of the database can only view the contents they are authorized to view. The rest of the database is out of bounds to them.The different permissions for ...
Read MoreCentralized Database Management System
A centralized database is stored at a single location such as a mainframe computer. It is maintained and modified from that location only and usually accessed using an internet connection such as a LAN or WAN. The centralized database is used by organisations such as colleges, companies, banks etc.As can be seen from the above diagram, all the information for the organisation is stored in a single database. This database is known as the centralized database.AdvantagesSome advantages of Centralized Database Management System are −The data integrity is maximised as the whole database is stored at a single physical location. This ...
Read MoreN-ary Relationship in Database
A relationship is an important part of any Entity relationship diagram as it shows the relation between two different entities. In an n - ary relationship, the n shows the number of entities in the relationship. It can be anything but the most popular relationships are unary, binary and ternary where the number of entities respectively are one, two and three.More information about Unary, Binary and Ternary relationships is as follows −Unary RelationshipWhen there is a relationship between two entities of the same type, it is known as a unary or recursive relationship. This means that the relationship is between ...
Read MoreFunctions in Oracle DBMS
The different types of functions in Oracle are −Oracle String FunctionsOracle Numeric FunctionsOracle Date FunctionsMore details about these functions are given as follows −Oracle String FunctionsThe following are the Oracle String Functions −ASCII(str)This function returns the ASCII or numeric value of the first word in the string str provided. If it is an empty string, it returns 0. For example:SQL> SELECT ASCII('Apple'); +---------------------------------------------------------+ | ASCII('Apple') | +---------------------------------------------------------+ | 65 | +---------------------------------------------------------+ 1 row in set (0.00 sec)This returns the ASCII value of A i.e. 65 as it is the first character in the string.CONCAT(str1, str2…..strn)This function returns the string that ...
Read MoreWhat kind of settings can we do to a text file by query while exporting the values from MySQL table into a text file?
While exporting the data from MySQL table to a text file we can use ‘FIELDS TERMINATED BY’, ‘ENCLOSED BY’, ‘LINES TERMINATED BY’ and other options too to put the values of fields in different settings of the text file. It can be illustrated with the help of the following example −ExampleSuppose we are having following data from table ‘Student_info’ −mysql> Select * from Student_info; +------+---------+------------+------------+ | id | Name | Address | Subject | +------+---------+------------+------------+ | 101 | YashPal | Amritsar | History | | 105 | Gaurav | Chandigarh | Literature | | ...
Read MoreHow can we import the text file, having some line prefixes, into MySQL table?
Suppose if we have a line prefix in the text file then with the help of using ‘LINES STARTING BY’ option we can ignore that prefix and import correct data into MySQL table. It can be understood with the help of the following example −ExampleSuppose we are using ‘VALUE’ as the ‘LINE PREFIX’ in the text file as follows −id, Name, Country, Salary VALUE:105, Chum*, Marsh, USA, 11000 106, Danny*, Harrison, AUS, 12000Now while importing this text file into MySQL table then we ...
Read MoreHow can we MySQL LOAD DATA INFILE statement with 'ENCLOSED BY' option to import data from text file into MySQL table?
Sometimes the input text files have the text fields enclosed by double quotes and to import data from such kind of files we need to use the ‘ENCLOSED BY’ option with LOAD DATA INFILE statement. We are considering the following example to make it understand −ExampleFollowings are the comma-separated values in A.txt file −100, ”Ram”, ”INDIA”, 25000 101, ”Mohan”, ”INDIA”, 28000We want to import this data into the following file named employee2_tbl −mysql> Create table employee2_tbl(Id Int, Name Varchar(20), Country Varchar(20), Salary Int); Query OK, 0 rows affected (0.1 sec)Now, the transfer of data from a file to a ...
Read MoreHow can we transfer information between MySQL and data files?
Transferring the information between MySQL and data files mean importing data from data files into our database or exporting data from our database into files. MySQL is having two statements that can be used to import or export data between MySQL and data files −LOAD DATA INFILEThis statement is used for importing the data from data files into our database. It reads data records directly from a file and inserts them into a table. Its syntax would be as follows −SyntaxLOAD DATA LOCAL INFILE '[path/][file_name]' INTO TABLE [table_name ];Here, the path is the address of the file.file_name is the name ...
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