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MySQL Articles
Page 87 of 355
How can I customize the output of MySQL SUM() function to 0 instead of NULL when there are no matching rows?
As we know that the SUM() function returns NULL if there is no matching row but sometimes we want it to return zero instead of NULL. For this purpose, we can use the MySQL COALESCE() function which accepts two arguments and returns the second argument if the first argument is NULL, otherwise, it returns the first argument. To understand the above concept, consider an ‘employee_tbl’ table, which is having the following records −mysql> SELECT * FROM employee_tbl; +------+------+------------+--------------------+ | id | name | work_date | daily_typing_pages | +------+------+------------+--------------------+ | 1 | John | 2007-01-24 ...
Read MoreWhat are the advantages and disadvantages of using MySQL stored procedures?
There are numerous advantages and disadvantages of using MySQL stored procedures which are as follows −MySQL Stored Procedure AdvantagesFollowings are the advantages of using MySQL Stored Procedures −Increasing the performance of applications − As we know that after creating the stored procedure it is compiled and stored in the database. But MySQL implements stored procedures slightly different which helps in increasing the performance of the applications. MySQL stored procedures are compiled on demand. After compiling a stored procedure, MySQL puts it into a cache. And MySQL maintains its own stored procedure cache for every single connection. If an application uses ...
Read MoreHow can we see only name and types of the stored routines in a particular MySQL database?
We can write the following query to see only the name and types of procedures in a particular MySQL database. To make it understand we are using the database named ‘query’ −mysql> Select Name, Type from mysql.proc where db = 'query'; +------------+-----------+ | Name | Type | +------------+-----------+ | allrecords | PROCEDURE | | Hello | FUNCTION | +------------+-----------+ 2 rows in set (0.18 sec)
Read MoreHow can we get some last number of characters from the data stored in a MySQL table's column?
To get some last number of characters from the data stored in MySQL table’s column, we can use MySQL RIGHT() function. It will return the number of characters specified as it argument. We need to provide the name of the column, having the particular record from which we want to get last characters, as its first argument. To demonstrate it we are taking the example of a table named ‘examination_btech’ having the following examination details of students −mysql> Select * from examination_btech; +-----------+----------+--------+ | RollNo | Name | Course | +-----------+----------+--------+ | 201712001 ...
Read MoreHow can we get only the name having no other details about the tables in MySQL database?
With the help of SHOW TABLES command, we can get only the name having no other information about the tables. For example, we can see the list of tables in a database named tutorial as follows −mysql> show tables; +--------------------+ | Tables_in_tutorial | +--------------------+ | student | +--------------------+ 1 row in set (0.00 sec)
Read MoreHow can we use MySQL SUM() function to calculate the sum of only dissimilar values of the column?
For calculating the sum of only dissimilar values of the column we can use ‘DISTINCT’ keyword along with the name of the column. To understand SUM() function for dissimilar values, consider an ‘employee_tbl’ table, which is having the following records −mysql> SELECT * FROM employee_tbl; +------+------+------------+--------------------+ | id | name | work_date | daily_typing_pages | +------+------+------------+--------------------+ | 1 | John | 2007-01-24 | 250 | | 2 | Ram | 2007-05-27 | 220 | | 3 | Jack | 2007-05-06 | 170 ...
Read MoreHow can we find the index position of a string stored as a record in MySQL table's column?
We can use FIELD() function to find the index position of a string stored as a record in MySQL table’s column. To demonstrate it we are using the table named ‘websites’ having the following dataExamplemysql> Select * from websites; +----+---------------+------------------------+ | Id | Purpose | Webaddress | +----+---------------+------------------------+ | 1 | For tutorials | www.tutorialspoint.com | | 2 | For searching | www.google.co.in | | 3 | For email | www.gmail.com | +----+---------------+------------------------+ 3 rows in set (0.00 sec)Now, suppose if we ...
Read MoreHow MySQL SUM() function evaluates if it is used with SELECT statement that returns no matching rows?
When MySQL SUM() function used with SELECT statement that returns no matching rows then there is nothing to evaluate and it returns NULL as output. Sometimes, we thought it must return 0 as output but 0 is a number itself and for no matching rows it not significant to return 0 hence it returns NULL. To understand the above concept, consider an ‘employee_tbl’ table, which is having the following records −mysql> SELECT * FROM employee_tbl; +------+------+------------+--------------------+ | id | name | work_date | daily_typing_pages | +------+------+------------+--------------------+ | 1 | John | 2007-01-24 | 250 ...
Read MoreWhat is the benefit of using MySQL SUM() function with GROUP BY clause?
When we use MySQL SUM() function with GROUP BY Clause the SUM() function evaluates the sum for every group specified in the GROUP BY clause. The benefit of using SUM() with GROUP BY clause is that we can easily find the total of a particular group. To understand the above concept, consider an ‘employee_tbl’ table, which is having the following records −mysql> SELECT * FROM employee_tbl; +------+------+------------+--------------------+ | id | name | work_date | daily_typing_pages | +------+------+------------+--------------------+ | 1 | John | 2007-01-24 | 250 | | 2 | Ram ...
Read MoreHow can we use MySQL SUM() function with HAVING clause?
By using MySQL SUM() function with the HAVING clause, it filters the result based on a specific condition given after the HAVING clause. To understand the above concept, consider an ‘employee_tbl’ table, which is having the following records −mysql> SELECT * FROM employee_tbl; +------+------+------------+--------------------+ | id | name | work_date | daily_typing_pages | +------+------+------------+--------------------+ | 1 | John | 2007-01-24 | 250 | | 2 | Ram | 2007-05-27 | 220 | | 3 | Jack | 2007-05-06 | ...
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