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Database Articles
Page 157 of 546
Why is it good to write the numbers in MySQL INTERVAL() function in ascending order?
Actually, INTERVAL() function uses the binary search for searching the bigger number than the number at first argument. So, that is why if we want INTERVAL() function to work efficiently the list of numbers would be in ascending order. Following is a good way to use INTERVAL() function −mysql> Select INTERVAL(50,20,32,38,40,50,55);
Read MoreWhat MYSQL INTERVAL() function returns if there is no bigger number in the list of arguments than the number at first argument?
In this case, MySQL INTERVAL() function returns the index number of the last number in argument list plus 1. In other words, the last index number in the list plus 1 would be returned by this function. Following example will demonstrate it −mysql> Select INTERVAL(50,20,32,38,40); +--------------------------+ | INTERVAL(50,20,32,38,40) | +--------------------------+ | 4 | +--------------------------+ 1 row in set (0.00 sec)
Read MoreIn MySQL, how IN() comparison function works?
Basically, IN() comparison function checks whether a value is within a set of values or not. If the value is within a set of values then it returns 1 otherwise 0. Its syntax can be as follows;Expression IN (val1, val2, …, valN)Here, The expression is the value that is to be searched within the set of N values within IN list.Val1, val2, …, valN is the set of N values, forms the IN list, from which the search happens.Examplemysql> Select 100 IN (50, 100, 200, 400, 2000); +------------------------------+ | 100 IN (50, 100, 200, 400, 2000) | +------------------------------+ | ...
Read MoreWhat is the use of MySQL IS and IS NOT operator?
In MySQL, both IS and IS NOT operators are used to test a value against a Boolean value.The syntax of IS operator can be as follows −Val IS Boolean_valHere Val is the value that we want to test against Boolean value.Boolean_val is the Boolean value against which the value would be tested and it can be TRUE, FALSE or UNKNOWN.The syntax of IS NOT operator can be as follows −Val IS NOT Boolean_valHere Val is the value that we want to test against Boolean value.Boolean_val is the Boolean value against which the val would be tested and it can be TRUE, FALSE or UNKNOWN.Following MySQL statements will demonstrate ...
Read MoreHow can I get the output based on comparison done with column’s name using MySQL IN() function?
In this scenario, we need to use the name of the column as ‘Expression’ which will then be compared with the values in the list. If a column has value/s matched within the list, the output would be produced. For understanding it, consider the example from employee table having the following data −mysql> Select * from Employee; +----+--------+--------+ | ID | Name | Salary | +----+--------+--------+ | 1 | Gaurav | 50000 | | 2 | Rahul | 20000 | | 3 | Advik | 25000 | | 4 | Aarav | 65000 | | 5 | Ram | 20000 | ...
Read MoreHow can I use MySQL IN() function to compare row constructors?
We can also use IN() function to compare row constructors. Consider the following example to make it clearer −mysql> Select (10,2) IN ((5,10),(10,2),(2,10),(100,100)); +--------------------------------------------+ | (10,2) IN ((5,10),(10,2),(2,10),(100,100)) | +--------------------------------------------+ | 1 | +--------------------------------------------+ 1 row in set (0.00 sec) mysql> Select (10,2) IN ((5,10),(2,10),(100,100)); +-------------------------------------+ | (10,2) IN ((5,10),(2,10),(100,100)) | +-------------------------------------+ | 0 | +-------------------------------------+ 1 row in set (0.00 sec)
Read MoreHow can we handle a result set inside MySQL stored procedure?
We can use a cursor to handle a result set inside a stored procedure. Basically a cursor allows us to iterate a set of rows returned by a query and process each row accordingly.To demonstrate the use of CURSOR within MySQL stored procedure, we are creating the following stored procedure which is based on the values, as shown below, of the table named ‘student_info’ −mysql> Select * from student_info; +-----+---------+----------+------------+ | id | Name | Address | Subject | +-----+---------+----------+------------+ | 101 | YashPal | Amritsar | History | | 105 | Gaurav | Jaipur | Literature ...
Read MoreWhen MySQL IN() function returns NULL?
Following are the two cases when MySQL IN() function returns NULL as result −Case-1 − When expression on left side is NULL IN() function will return NULL if the expression on the left side is NULL. Following example will demonstrate it −mysql> Select NULL IN (1, 2, 3, 4, 10); +----------------------+ | NULL IN (1, 2, 3, 4, 10) | +----------------------+ | NULL | +----------------------+ 1 row in set (0.00 sec)Case-2 − When one of expression in the list is NULL and no match is foundIN() function will return NULL if it does ...
Read MoreIn MySQL, how can we declare a handler while handling errors?
It is very important to handle the errors by throwing a proper error message. MySQL provides a handler to handle the error. We can declare a handler with the help of the following syntax −Syntax of handlerDECLARE handler_action FOR condition_value statement;The above syntax shows that we need to use DECLARE HANDLER statement to declare a handler. If a condition whose value matches the condition_value then MySQL will execute the statement and continue or exit the current code block based on the action. Followings are the three major things in the above syntax −Handler_action is of two types and can accept one ...
Read MoreHow can MySQL REPLACE() function be used with WHERE clause?
As we know that WHERE clause is used to put condition/s in MySQL query and MySQL returns result set based on those conditions. Similarly when we use REPLACE() function with WHERE clause, the result set will depend upon the conditions provided. Following is an example by using data from the ‘Student’ table in which REPLACE() function replaces the records of a column ‘Name’ in which the value of column ‘Subject’ is ‘Computers’.Examplemysql> Select Name, REPLACE(Name, 'G', 'S') from student Where Subject = 'Computers'; +--------+------------------------+ | Name | REPLACE(Name, 'G', 'S') | +--------+------------------------+ | Gaurav | Saurav ...
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