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The easiest way to extract the maximum numeric value from a string using regex is to −Use the regex module to extract all the numbers from a stringFind the max from these numbersFor example, for the input string −There are 121005 people in this city, 1587469 in the neighboring city and 18775994 in a far-off city.We should get the output −18775994We can use "\d+" regex to find all numbers in a string as \d signifies a digit and the plus sign finds the longest string of continuous digits. We can implement it using the re package as follows −import re ... Read More
MySQL allows us to pass only one argument to the CONCAT() function. In this case, MySQL returns the same argument as output. Following example will exhibit it −Examplemysql> Select Concat('Delhi'); +-----------------+ | Concat('Delhi') | +-----------------+ | Delhi | +-----------------+ 1 row in set (0.00 sec)
When there is a relationship between two entities of the same type, it is known as a recursive relationship. This means that the relationship is between different instances of the same entity type.Some examples of recursive relationship can be shown as follows −An employee can supervise multiple employees. Hence, this is a recursive relationship of entity employee with itself. This is a 1 to many recursive relationship as one employee supervises many employees.A person can have many children who are also persons. Hence, this is a recursive relationship of entity person with itself. This is a 1 to many recursive ... Read More
A string function called CONCAT() is used to concatenate two or more strings as a single string in MySQL.SyntaxCONCAT(String1,String2,…,StringN)Here, the arguments of CONCAT functions are the strings which need to be concatenated as a single string.Examplemysql> Select CONCAT('Ram','is','a','good','boy') AS Remarks; +---------------+ | Remarks | +---------------+ | Ramisagoodboy | +---------------+ 1 row in set (0.00 sec)
The distributed database management system contains the data in multiple locations. That can be in different systems in the same place or across different geographical locations.As shown in the below example −The database is divided into multiple locations and stores the data in Site1, Site2, Site3 and Site4.The advantages and disadvantages of Distributed database management systems are as follows −Advantages of DDBMSThe database is easier to expand as it is already spread across multiple systems and it is not too complicated to add a system.The distributed database can have the data arranged according to different levels of transparency i.e data ... Read More
Open source databases are those databases who have an open source code i.e anyone may view the code, study it or even modify it. Open source databases could be relational (SQL) or non relational (NoSQL).Why use Open Source Databases?It is quite expensive to create and maintain a database for any company. A huge chunk of the total software expenditure is used to handle databases. So, it is feasible to switch to low cost open source databases. This saves companies a lot of money in the long run.Open Source Databases in useThere many different open source databases in the market. All ... Read More
MySQL BIT_LENGTH() string function is used to get the length of the string in bits.SyntaxBIT_LENGTH(Str)Here Str, the argument of BIT_LENGTH() function, is the string whose BIT_LENGTH value is to be retrieved. Str can be a character string or number string. If it is a character string then it must be in quotes.Examplemysql> Select BIT_LENGTH('New Delhi'); +-------------------------+ | BIT_LENGTH('New Delhi') | +-------------------------+ | 72 | +-------------------------+ 1 row in set (0.00 sec) mysql> select BIT_LENGTH(123456); +--------------------+ | BIT_LENGTH(123456) | +--------------------+ | 48 | +--------------------+ 1 row in set (0.00 sec)
Whenever we want to pass an empty string as a parameter to BIT_LENGTH() function then we must have to pass blank quotes (even without any space). It cannot pass without quotes because MySQL then resembles it as the function without any argument and returns an error. But, when we pass an empty string with blank quotes then MySQL will return 0 as output. It can be understood with the following example as well −Examplemysql> Select BIT_LENGTH(); ERROR 1582 (42000): Incorrect parameter count in the call to native function 'BIT_LENGTH' mysql> Select BIT_LENGTH(''); +----------------+ | BIT_LENGTH('') | +----------------+ | 0 ... Read More
Mobile databases are separate from the main database and can easily be transported to various places. Even though they are not connected to the main database, they can still communicate with the database to share and exchange data.The mobile database includes the following components −The main system database that stores all the data and is linked to the mobile database.The mobile database that allows users to view information even while on the move. It shares information with the main database.The device that uses the mobile database to access data. This device can be a mobile phone, laptop etc.A communication link ... Read More
Multidimensional databases are used mostly for OLAP (online analytical processing) and data warehousing. They can be used to show multiple dimensions of data to users .A multidimensional database is created from multiple relational databases. While relational databases allow users to access data in the form of queries, the multidimensional databases allow users to ask analytical questions related to business or market trends.The multidimensional databases uses MOLAP (multidimensional online analytical processing) to access its data. They allow the users to quickly get answers to their requests by generating and analysing the data rather quickly.The data in multidimensional databases is stored in ... Read More