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Introduction to MySQL AverageTo find the average of a field in various records, we use MySQL Average. We can find the average of the records of a column by using the “Group by” clause.MySQL AVG() function is an aggregate function that allows you to calculate the average value of column values. To calculate the average of the distinct values from a column, we can use the “DISTINCT” operator. AVG function will ignore “NULL” values.
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AVG function can be used in the subqueries. It can be used along with the control flow functions like IF, IFNULL, NULLIF, and CASE.
Syntax:
Here above is the syntax of the Average function. The average function returns the data of the INT datatype.
How Does MySQL Average Work?Now let us create a table, perform the average function on the column, and retrieve the data.
Query:
create table Freelancer_data ( Freelancer_id INT, Freelancer_Name VARCHAR(20), Type_of_work VARCHAR(30), No_of_submission INT, No_of_pages_submitted INT, EMAIL varchar(30) ); 1. Insert data Into the TableQuery:
2. Select the Data from the Table select * from freelancer_data;Output:
3. Now let us find the average Pages Submitted by the FreelancerQuery:
select AVG(No_of_pages_submitted) as "Average papers submitted" from freelancer_data;Output:
Now let us find the average pages submitted by the freelancer based on the Type_of_work using the “GROUP BY” clause:
Query:
select AVG(No_of_pages_submitted) as "Average papers submitted", Type_of_work from freelancer_data group by 2;Output:
or
Query:
select AVG(No_of_pages_submitted) as "Average papers submitted", Type_of_work from freelancer_data group by Type_of_work;Output:
4. Using AVG() With “HAVING” ClauseTo set conditions for the output of the average values, we use the “HAVING” clause.
Query:
select AVG(No_of_pages_submitted) as "Average papers submitted", Type_of_work from freelancer_data group by 2or
Query:
select AVG(No_of_pages_submitted) as "Average papers submitted", Type_of_work from freelancer_data group by Type_of_workOutput:
5. Using AVG() with sub-queryIn the sub-query, we find the average based on “type_of_work”. The outer query gets the average for the output of the inner query.
Query:
SELECT AVG(AVG_PAGES) as "average pages"/* Outer query*/ FROM (select AVG(NO_OF_PAGES_SUBMITTED) AS "AVG_PAGES" /* -- inner query --*/ from freelancer_data GROUP BY TYPE_OF_WORK) AVG;Output:
6. Using AVG() with Control functionsLet us find the average of the pages submitted if the “no_of_submission” is 3. Else, consider it as “null”. As AVG ignores the NULL values, the below output is average for only the submission count is =3.
SELECT AVG(IF(No_of_submission= 3, No_of_pages_submitted, NULL))/No_of_submission 'Avg pages' FROM freelancer_data;Output:
Example to Implement MySQL AverageNow let us consider other simple examples below:
Query:
create table sample_AVG ( ID INT, NAME VARCHAR(30), DEPT_NO INT, SALARY FLOAT(10,2) ); 1. Insert data Into the TableQuery:
insert into SAMPLE_AVG values (1278,'Jack', 2, 90000); insert into SAMPLE_AVG values (2278,'Will', 2, 80000); insert into SAMPLE_AVG values (3278,'Rose', 3, 78000); insert into SAMPLE_AVG values (4278,'Ben', 3, 45000); insert into SAMPLE_AVG values (5278,'Stuart', 3, 67000); insert into SAMPLE_AVG values (6278,'Rample', 4, 57000); insert into SAMPLE_AVG values (7278,'Jackern', 4, 47000); insert into SAMPLE_AVG values (8278,'fred', 4, 68000); insert into SAMPLE_AVG values (9278,'Gram', 4,86000);Query:
select * from SAMPLE_AVG;Output:
2. Now let us find the average of salary from the TableQuery:
select AVG(salary) as "Average salary" from sample_avg;Output:
3. Now let us find the average SALARY based on the DEPT_NO using the “GROUP BY” ClauseQuery:
select AVG(salary) as "Average salary", Dept_no from sample_avg group by 2; /* - - Position of the column - -*/Output:
or
Query:
select AVG(salary) as "Average salary", Dept_no from sample_avg group by dept_no; 4. Using AVG() With “HAVING” ClauseTo set conditions for the output of the average values, we use the “HAVING” clause.
Query:
select AVG(salary) as "Average salary", Dept_no from sample_avg group by 2or
Output:
Query:
select AVG(salary) as "Average salary", Dept_no from sample_avg group by dept_noOutput:
5. Using AVG() with sub-queryIn the sub-query, we find the average based on “dept_no”. The outer query gets the average for the output of the inner query.
Query:
SELECT AVG(AVG_SAL) as "average salary" FROM (select AVG(salary) as "Avg_sal", Dept_no from sample_avg group by 2 )AVG;Output:
6. Using AVG() with Control FunctionsHere let us find the SALARY average if the “DEPT_NO” is in 3, 4 else, consider it “null”. As AVG ignores the NULL values, the below output is average for only the submission count is 3 and 4.
Query:
SELECT AVG(IF(DEPT_NO IN (3,4), SALARY, NULL))/COUNT(DEPT_NO) 'AVGSALARY' FROM SAMPLE_AVG;Output:
Conclusion
To find the average of a field in various records, we use MySQL Average. We can find the average of the records of a column by using the “Group by” clause.
MySQL AVG() function is an aggregate function that allows you to calculate the average value of column values.
To calculate the average of the distinct values from a column, we can use the “DISTINCT” operator. AVG function will ignore “NULL” values.
AVG function can be used in the subqueries. It can be used along with the control flow functions like IF, IFNULL, NULLIF, and CASE.
Recommended ArticlesWe hope that this EDUCBA information on “MySQL Average” was beneficial to you. You can view EDUCBA’s recommended articles for more information.
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How Does C++ Shuffle Work With Examples
Definition of C++ shuffle()
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Syntax:
void shuffle (RandomAccessIterator first, RandomAccessIterator last, URNG&& g);
Let us check what each keyword and parameter signify in this function
We call the RandomAccessIterator. The first parameter points to the position of the first element in the range, which will be rearranged.
The second parameter points to the last element in the range, which will be rearranged. For this also, it will be pointing to random access iterator.
The last parameter, g, is a special function object that helps us generate random numbers. It is called a uniform random number generator.
The return value of this function will be none.
How does C++ shuffle Work?Using the C++ shuffle function is easy. Let us check how it works.
Code:
{ for (int i: vec) { std::cout << i << ‘ ‘; } } int main() { std::shuffle(vec.begin(), vec.end()); shuf(vec); return 0; }
We must import the vector library to use the shuffle() function. The user-defined function displays the shuffled vectors. We have created a vector with a few numbers in the main function. The shuffle() function has a beginning and an end which takes the vector elements and shuffles them. Once this is done, we call the function to print the shuffled array. We have not specified the random generation function; hence it will take the default function, which can be used. It will rearrange the elements in the vector. The function will swap the value of each element with any other randomly picked element from the same vector. It works with generators that work like the rand() function. To use this function without a generator, we can use the random_shuffle(). Let us check a few examples to help us understand the function better.
Examples of C++ shuffle()Following are the examples given below:
Example #1using namespace std; int main () { unsigned num = chrono::system_clock::now().time_since_epoch().count(); shuffle (shuf.begin(), shuf.end(), default_random_engine(num)); cout << “The numbers after shuffling are:”; for (int& x: shuf) cout << ‘ ‘ << x; cout << ‘n’; return 0; }
Output:
Code Explanation: The above code is an example of a shuffle function. We have used the iostream, array, random, and Chrono libraries. Here the Chrono library is used to create a random generator. We have taken an array with a size of 8 integers. Here we have defined this array, and then we are using the random generator function using the Chrono library. We are generating a random number using the epoch() and now() function which is a part of the clock library. It creates a pattern using which the numbers are shuffled. Then we have called the shuffle function, where we define the start and end of the array, and the third parameter is the variable that stores the calculation for random number generation. We then print the randomly shuffled array at the end of the program. Below is the output of the above program.
Example #2Code:
using namespace std; void edu_shuffle(int arr[], int n) { unsigned rnd = 0; shuffle(arr, arr + n, default_random_engine(rnd)); for (int i = 0; i < n; ++i) cout << arr[i] << " "; cout << endl; } int main() { int arr[] = { 18, 23, 30, 47, 87, 49}; int num = sizeof(arr) / sizeof(arr[0]); edu_shuffle(arr, num); return 0; }Code Explanation: In this program, we have imported a library and created a user-defined function, edu_shuffle. This function first creates an unsigned integer variable that will store the random generation calculation. We then use the shuffle() function, passing the start and end of elements between which the shuffling should occur. In place of random generation, we have used an inbuilt function default_random_engine to create a random number. In the main function, we calculated the end of the elements sent to the edu_shuffle function. We have used the sizeof function. We have sent these as parameters to the user-defined function, which helps execute the shuffle() function. The output of the above function will be as below:
Advantages of C++ shuffle()
The shuffle function helps in generating a random sequence of numbers easily.
This function swaps numbers with internal elements quickly.
If no random generator function is specified, the shuffle() function default will be taken.
It is fast and efficient, which makes it easy to use
The randomness of numbers can be built and used with the C++98/03 standard.
ConclusionThe shuffle() function is an easy way of rearranging the elements of a vector or array. A random generator variable can be used to generate the pattern of random numbers. The library plays a role in defining the “else” pattern by utilizing the default functionality provided by the function. It actively swaps the elements within a given range. This range can be between any elements in the array. This function is similar to the random_shuffle() function. The only difference is shuffle() uses a uniform random number generator.
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Examples On How Does Class Work In Perl
Definition of Perl Class
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How to Declare Perl Class?The procedure is as follows.
It is very easy and simple to declare. To declare any class we need to mention package keyword before the class name.
Syntax:
Package class_name;Parameter:
Below is a parameter description of Perl declare syntax.
Package: Package is nothing but a specified namespace within the Perl code or program which contains sub-routines or user-defined variables. The package is very important at the time of declaring the class.
Class name: We can define any class name to the program in Perl. But it is specific to the program which we have implemented.
A package name in perl class is subroutines or a user-defined variable. We can reuse this again in the code.
Package in perl will provide namespace within the program mostly which contains subroutines and variables.
The scope of class or package will end of the file or until we cannot create another package in one file.
Below is the example to declare per class is as follows.
Example:
Package declare_perlClass;
In the above example, we have declared class name as declare_perlClass. This class corresponds to a package name.
Before declaring declare_perlClass class firstly we need to load the package in Perl.
A loaded package is used in throughout the program. The scope of the package is throughout the program or until we define another package.
How does Class Work in Perl?The working is as follows:
It is defined as it is a package that having constructor to create perl object, this object is having any type of variable but mostly it is a reference to array or hash is used.
It is nothing but a concept of data structures. It defines the object of data in perl.
To define we need to build a package first, the package is nothing but sub-routines or user-defined variables.
The object is nothing but an instance of the class.
It is very easy and simple to define, Itl is corresponding to a package of perl in its simplest form.
It is most important and useful in Perl to define Perl’s object.
We have to take the example of class as an employee. We have defining member function and data members using the class as an employee.
There may be an employee with different names and structures but all of them have some common characteristics like emp_id, emp_dept, and emp_name.
Here we have to define an employee as a class with emp_id, emp_dept, and emp_name as data members.
We have also used a bless function.
Syntax bless function:
bless name_of_object, name_of_class;
We can also create an object by using a perl class. We have to create an object based on the class name.
Data member in perl class is nothing but data variables and member function is a function which manipulated the variables.
In the below example, we have to define member variable as emp_id, emp_dept and emp_name.
We can define any class name to the program in perl. But it is specific to the program which we have implemented.
In the above example we have to define class name as employee and data member as emp_id, emp_dept and emp_name.
ExamplesThe examples are as follows:
Example #1 – Using bless function in perl class:
In the below example, we have created perl class using bless function. We have created a class name as an employee.
Member variables of class name is ’emp_id’ and ’emp_salary’.
We have defined a bless function. In bless function, we have to define object name and class name.
We have also define constructor of employee class name as new_emp to define member variables.
Code:
use strict; use warnings; package employee; ## Constructor of employee class. sub new_emp{ #the package name 'employee' is in the default array shift. my $class = shift; #object of a class. my $self = { }; #blessing with object name and class name bless $self, $class; #returning object from constructor return $self; } 1; print "emp_id:- 101n"; print "emp_salary:- 25000n"; Example #2 – creating class and using objects
In the below example we have created perl class using an object. We have created class name as an employee.
Member variables of class name is ‘Employee_FirstName’ and ‘Employee_LastName’.
We have defined a bless function. In bless function, we have to define object name and class name.
We have also define constructor of employee class name as employee_data to define member variables.
Code:
use strict; use warnings; package employee; ## This is the class of employee. sub employee_data ## Constructor of employee class. { # Shift is default array will used in 'employee' class and then assign # it to employee class variables my $class_name = shift; my $self = { }; # using bless function. bless $self, $class_name; # returning object from constructor of employee_data. return $self; } # Object creating name as employee from employee_data and calling a constructor. my $Data = employee_data employee("Emp_FirstName:- ABC", "Emp_LastName:- PQR"); # printing the dataOutput:
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How Does Printf Function Work In Perl With Examples
Introduction to Perl printf
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Syntax:
The Perl scripts have default keywords, functions and scalar variables that means the variable accepts only the single value. It can be any numbers, letters, characters, digits with operators, but the first character of the variable always must be the letter or symbol; like the underscore operator, it’s not a digit.
$ variable name = value; printf(" ", $variable name); ---some Perl script logics--- How does the printf Function Work in Perl?
The Perl script printf() method prints only the user datas with the specified format specifiers on the screen. Actually, the function prints only the values, which is interpreted using the List datas through via using some format specifiers with the current result as the output. The filehandle concept is used for more space in the printf function, which handles the errors and exceptions by using exception classes and modules but the printf() function that prints the outputs by using some format specifiers. Generally, the printf function used some properties which are related to their fields and attributes.
Like that this function as many of the properties are to be same as the print function in the script. That’s the way it shows the better output format, which has already related to their user inputs. This is more similar to the field specifiers with co-related to their text string format specifiers with some delimiters like comma, semi-colon, underscore etc. Using some Regular Expressions concepts, the user inputs are to be validated and evaluated at the back end codes, showing the output on the user screen.
Examples of Perl printfGiven below are the examples of Perl printf:
Example #1Code:
$var = 1562.45; $strn = ("Welcome To My Domain"); printf("Hi user your input is $%6.3f and converted output is %snn", $var, $strn);Output:
Explanation:
In the above example, we used two variables like $var and $strn, and both the variables are used with some formats like $var variable assigned values are only the float type of numbers so the decimal point of results to be expected once the given variable is executed on the script like that it will be printed on the user screen.
Same time the next variable $strn accepts only the string values like “Welcome to My domain”, so it’s a string format it specifies the user information’s the printf function which has passed the calls to the string and also the field is specified to the variables and then it will insert into the memory locations for separate positions.
Example #2Code:
printf("Welcome To My Domain:n"); printf("'%7d'n", 7); printf("'%7d'n", 596903); printf("'%7d'n", -94758); printf("'%7d'n", -904685); printf("n"); printf("Have a Nice Day:n"); printf("'%-8d'n", 785); printf("'%-8d'n", 1023894785); printf("'%-8d'n", -923487568); printf("'%-8d'n", -1293475); printf("n"); printf("n"); printf("Thanks for your interest in our application:n"); printf("'%09d'n", 3); printf("'%09d'n", 223); printf("'%09d'n", 9234687); printf("'%09d'n", -9238747); printf("'%09d'n", -2390478); printf("'%04d'n", 23); printf("'%04d'n", 'Welcome'); printf("'%04d'n", 'Welcome34'); printf("'%04d'n", -9243747); printf("'%04d'n", -4590478); printf("'%02d'n", 'Tyujk'); printf("'%02d'n", 'udg 4857 sdhfg'); printf("'%02d'n", 9238747); printf("'%03d'n", -93476538747); printf("'%02d'n", -239754478);Output:
Explanation:
In the second example, we have used the same printf function in different ways. We can pass the inputs in numbers that will be the integer, float, decimal, short, long and double; it can be any of the types passing into the function, and it is converted into the required output format.
Some formats will follow the rules and control the fields with some heights, widths, and even other fields like printing left-justified, right-justified and zero-filled numbers stored in the variables for calculating their functions and storages the memory locations. It accepts both positive and negative numbers followed by its signatures and its relevance to their usages.
Example #3 printf("'%4s'n", "Welcome"); printf("'%76s'n", "Welcome"); printf("'%-76s'n", "Welcome"); printf("Welcome To My Domainn"); printf("Have a Nice Dayn"); printf("kjadgvds hasjkgdf ashdjfh jsdhfhj ajsgn"); printf("WelcometTo My Domainn"); printf("jasg hsagdfj skjdfhk skdh shfj sjn"); printf("Welcomen To My Domainn"); printf("kjshdfj kjahksj nkjh 2734 shj2983 3974y kn"); printf("C:UsersKripya-PCDocumentsarticles\n"); printf("hsdfjg jhajs kjaskdj kjaksd jaskn"); printf("weh jkhj kawj kwejk jwlkl lkwqejkwlkqjlkn"); printf("'%.3f'nn", 873.974); printf("87v hk jskj oi3y khk38 i347 bi3748n"); printf("'%.5f'n", 873.975); printf("jdshj38 3784 3748687j he83sk 94n"); printf("'%6.4f'n", 748.28374); printf("u3928 oiwu498y bu4589 io349 b3974n"); printf("'%7.14f'n", 734.837495); printf("3749 yiwe b843 sekk48905 je48n"); printf("'%06.4f'n", 83.8346); printf("2638 hy3w8 j8939475 jbi34y8b wu4985b 3u984y bu498n"); printf("'%-6.3f'nn", 857.98374); printf("26837 hjkwehr234yv hj gu4 s h jkh jkjkh 3987n"); printf("'%-5.25f'n", 8347958.892365);Output:
Explanation:
In the printf() function, we used both numbers and string characters in various format specifiers, and even some comparison operators are used and called with the same reference names. Because the printf function used some operators allowed with string formats and it has generated the reports with formats and even though the formatted holds with the some numbers that can be called through with the help of some conversions.
And these conversions will used some operators like the % sign with the end of the characters even though the same number of characters are assigned through its conversions. Using some exponential notations is required for the printf function.
ConclusionIn conclusion, they must have some built-in methods for printing the outputs on the screen for each programming languages. Likewise, each method has its own attributes and properties for showing its results as much as needed from the user perspective. In Perl, the printf function used some format specifiers for displaying the outputs on the user screen.
Recommended ArticlesThis is a guide to Perl printf. Here we discuss the introduction; how does the printf function work in Perl? and examples, respectively. You may also have a look at the following articles to learn more –
How To Dump Mysql Server With Examples?
Introduction to MySQL Dump
In case the system’s database is corrupted, crashed, or lost, we should be able to restore the data in the database. For this reason, MySQL provides us with a facility to dump the database using mysqldump utility. You can use this utility only if you have access to your database, you have been assigned the select privilege on the tables of that database, and the database is currently running. The utility creates a logical backup and generates a flat file containing SQL statements. Later on, you can execute these SQL statements to restore the database to the same state it was in when the backup file was created. This utility supports both single and multiple database backups. Additionally, the mysqldump utility has the capability to export the data in XML, CSV, or any other delimited text format.
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We must dump our database frequently to have the updated backup of the database available to us. Whenever the backup is restored the database will be back to the state when that dump file was being created using mysqldump.
Pre-requisitesThere are certain privileges on the tables, views, triggers, and transactions that we should have to use the mysqldump utility. It depends on the content that we are backing up. If we are backing up the database that contains tables then you should have select privilege, for views it is necessary to have SHOW VIEW privilege, for triggers TRIGGER privilege and if we use –the single-transaction option while dumping the database then the LOCK TABLES privilege should be there with us.
Similarly, while reloading or restoring the dumped data, we must possess the privilege such as CREATE, INSERT, and ALTER privileges that might be present in your dumped flat file that will be executed. The ALTER statements may be present in the dumped file sometimes when stored programs are dumped for encoded character preservations. To execute this ALTER command and modify the database collation, the user must have the ALTER privilege assigned to them.
Syntax of MySQL DumpDumping one or more of the selected tables:
Dumping one or more of the selected databases:
Dumping Complete MySql ServerSyntax of dumping complete mysql server are:
Many options we can use to specify the behavior or values of some of the objects like -u for the username using which we will login -p to mention the password and other options related to defining the behavior of dumping. There are many different types of options that can be specified. We categorize them into the following types: –
Connection Options
Option-File Options
DDL Options
Debug Options
Help Options
Internationalization Options
Replication Options
Format Options
Filtering Options
Performance Options
Transactional Options
To see a complete list of the options that are available and can be used, we can execute the following command –
mysqldump -u root p –helpthat gives the following output displaying all the options and usage of the same:
as the list is too big, you can export it tho the file and then open the file to view the options and search for options that can be used in your context and use case. You can export the output to a file by executing the following command:
Output:
And the temp file when opened on an editor looks like the following:
Examples of MySQL DumpLet us consider one example, we will firstly query on my database server to display all databases –
show databases;Output:
Now, we will use educba database and check the tables present in it.
use educba; show tables;Let us now see all the records present in the developers table.
select * from developers;Output:
Now, let us export the educba database using the mysqldump command –
Output:
Note that we will have to exit from the MySQL command shell and then execute the above command. After, a file named chúng tôi file will be created on the same path. After opening the file, we will see that it contains all the commands of SQL that will recreate the educba database in case if we restore this file to a certain database. Here’s how that file will look like:
This is the dumped flat-file that was created after performing a dump of the ‘educba’ database. The file consists of commands to create the database, create a table, and insert queries to populate the table with records.
Restoring the DatabaseLet us now drop the database educba using the following command –
DROP DATABASE educba;Output:
And now confirm the available databases by using the command –
show databases;Output:
We can see that the educba database does not exist in our database server of MySQL. Now, we will restore the educba database from the backup file chúng tôi that we created by dumping the educba database previously.
You can restore the database using the following command:
sudo mysql -u root -p < backupOfEducba.sqlOutput:
Let us check the contents of the backup_educba database
show database; use educba; MySQL select * from developers;Output:
Upon restoration, it becomes evident that the database named ‘educba’ is reestablished, and it encompasses identical content as that of the ‘developer’ table, including all the records within.
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How To Use The Mysql Replace & Query Examples
Introduction to MySQL REPLACE
The MySQL REPLACE function is one of the string functions used to replace all existences of a substring within the main string to result in a new substring.
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The MySQL REPLACE function includes three parameters. The first parameter represents the main string where the replacement will occur. The other two parameters specify the substring to be replaced within the first string and the new substring for replacement.
This task in MySQL makes a case-sensitive function implementation while the string replacement process.
Hence, MySQL allows us to replace an old string with the new one in a column of the database table to perform any handy search and replace the needed one with the existing record value.
SyntaxThe MySQL REPLACE function is used with the following syntax:
REPLACE(Original_String, Substring1, Subtring2)
Original_String: This term denotes the main string in which the new one replaces the old string.
Substring1: This is the required occurrence of the substring to be replaced present in the original string.
Substring2: This is the required substring with the help of which a new substring can be replaced from the old one.
How does the REPLACE function work in MySQL?First, Let us check a simple example to learn the implementation of REPLACEfunction in MySQL. The query is written as follows, where the original string is “VBN” and the substring “B” within “VBN” will be replaced by the new string “X”:
SELECT REPLACE("VBN HJB", "B", "X");Result:
As per the above query, the valid expression is specified to replace the old string with the new one in the main string. The function executes to replace all the occurrences of the second argument in a specified string using the desired new one.
Thus, Using the REPLACE function in MySQL, we can effectively handle spelling mistakes in columns and perform searches for words that may not be accurate or valid. We can update the records by replacing specific characters with appropriate ones to obtain the desired results.
In this way, for a column value replacement, let us take the statement as follows:
UPDATE Person SET Person_Address = REPLACE(Person_Address,'Jaiput','Jaipur');This above helps to find all the occurrences of a spelling error in the column of the address of the table person and updates it with the correct one. For the function, the first parameter defines the specified column name without quotes, and the other two denote the substrings, which are responsible for replacing each other to produce a new string.
We should know that if we apply quotes with the field column in the function like ‘Person_Address’, then. As a result, the values of that column will be updated by this ‘Person_Address’. This will cause a sudden data loss of that column in the table.
Note that MySQL REPLACE function will make logical sense only if there exists a Primary Key or a Unique key in the table database so that the function can determine a new row without going through duplicity to make a replacement using indexes of the table; otherwise, it will be corresponding to an INSERT statement.
Also, learn that this function does not upkeep regular expression. If we want to substitute any text string using a specific pattern, we need to use a user-defined MySQL function, i.e., UDF from an external library.
Examples of MySQL REPLACEWe will execute the below queries, which show various ways to use this MySQL REPLACE string function in a database table:
Let us take a basic example of using MySQL REPLACE function:
Code:
Output:
2. Correcting invalid String characters within a wordWe are replacing the word ‘Learnint’, correcting a spelling error with the ‘g’ substring, and removing it.
Code:
SELECT REPLACE("Learnint","t", "g");Output:
3. Replace the substring containing numbersLet us suppose the below query to replace a specific number string:
Code:
SELECT REPLACE("477", "7", "9");Output:
4. Replace string using the Column name of a table and SELECT StatementConsidering a sample table named Books, we will use the MySQL REPLACE function in the query to show the string exchange of column values having the substring within it.
Code:
select * from Books;For example, the query is executed as below to display the result:
Code:
SELECT BookID,BookName,Language, REPLACE(Language, 'English', 'Eng') AS 'Replaced Language' FROM books;Output:
5. Replace string Example With SELECT & WHERE statementWe are now using the MySQL REPLACE function for a column of the Books table using a SELECT statement and will interchange the book name column string having a substring within the value to a new substring applied to the search. Table Books:
Code:
select * from Books;The query is below:
Code:
SELECT BOOKID, BOOKNAME, REPLACE(BOOKNAME,'Science','Sci') FROM Books2 WHERE BOOKNAME = 'Nuclear Science';Output:
6. MySQL REPLACE function with the UPDATE statementCode:
UPDATE TableName SET ColumnName = REPLACE(ColumnName, Substring1, Substring2) WHERE CondExpr;//condExprs: Conditional expressionFor example, taking the sample table Person, we perform the below query:
Code:
UPDATE Books2 SET BOOKNAME = REPLACE(BOOKNAME,'Networking','Computer Network'); select * from Books2;Output:
Code:
update Books set PRICE = '2000' where BOOKID = 107; select * from Books;Output:
7. Case Sensitive ErrorIf we execute the below query in MySQL, then the result will be as follows:
Code:
SELECT REPLACE('APPLE', 'e', 'g');Output:
In this way, The MySQL REPLACE function supports a case-sensitive search for a string that needs to be replaced, resulting in a new value. So, we must specify valid string expressions on which we want to perform the search and replacement. If not, the result will be the same as the original one.
ConclusionThis article taught us about the MySQL REPLACE function and how to exchange an old string with a new one.
Thus, the MySQL REPLACE function helps to substitute text in a table column for tasks such as interchanging the obsolete link, fixing any spelling error in the database records, etc.
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