Article Categories
- All Categories
-
Data Structure
-
Networking
-
RDBMS
-
Operating System
-
Java
-
MS Excel
-
iOS
-
HTML
-
CSS
-
Android
-
Python
-
C Programming
-
C++
-
C#
-
MongoDB
-
MySQL
-
Javascript
-
PHP
Database Articles
Page 544 of 546
How does the value of system variable max_allowed_packet affect the result of a string-valued function?
String-valued functions return NULL if the length of the result would be greater than the value of the max_allowed_packet system variable. Actually, max_allowed_packet is a dynamic global variable which can accept the integer type values. These values can be set for a session only. It can accept 1024 as the minimum value and 1073741824 as the maximum value. The by the default value of this system variable is 1048576.
Read MoreHow can we apply AUTO_INCREMENT to a column?
AUTO_INCREMENT means that the column will get the value automatically. To illustrate it we have created a table ‘employees’ as follows − mysql> Show Create Table employees\G *************************** 1. row *************************** Table: employees Create Table: CREATE TABLE `employees` ( `Id` int(11) NOT NULL AUTO_INCREMENT, `Name` varchar(35) DEFAULT NULL, PRIMARY KEY (`Id`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 1 row in set (0.00 sec) From the above result set, we can see that column id is given the auto-increment option. Now, when we will insert the value in Name ...
Read MoreWhat happens to MySQL temporary tables if MySQL session is ended?
Temporary table would be deleted if MySQL session terminates. After login again, on issuing the SELECT command we will find no data available in the database. Even our temporary table will not exist.
Read MoreWhat are the drawbacks of using test database?
There is a database named test in the list of databases displayed by the statement SHOW DATABASES. We can use test database but the main disadvantage is that anything created in this database can be removed/changed by anyone else with access to it. To avoid this we should take permission from MySQL administrator to use a database of our own. For taking permission following command must be run − mysql> grant all on tutorial.* to root@localhost; Query OK, 0 rows affected (0.10 sec) In the above command, I am taking permission for the tutorial database. Root is the ...
Read MoreHow MySQL behaves if I use INTERVAL keyword with an invalid date?
Actually, the behavior of MySQL depends upon the allow_invalid_dates mode. If this mode is enabled then MySQL will accept the invalid date and it would perform the date arithmetic as it performs with a valid date. Otherwise, if this mode is inactive then it will not accept the invalid date and would produce NULL as output. mysql> select '2017-02-30' + INTERVAL 7 day; +-------------------------------+ | '2017-02-30' + INTERVAL 7 day | +-------------------------------+ | NULL ...
Read MoreWhat happens if the output of MySQL TIMEDIFF() function surpass the range value of TIME field?
As we know that the range of TIME field in MySQL is ‘-838:59:59’ to ‘838:59:59’. Now, if TIMEDIFF() function’s output surpasses this range then MySQL will return either ‘-838:59:59’ or ‘838:59:59’ depends upon the values of the argument. Example mysql> Select TIMEDIFF('2017-09-01 03:05:45', '2017-10-22 03:05:45')AS 'Out of Range TIME Difference'; +------------------------------+ | Out of Range TIME Difference | +------------------------------+ | -838:59:59 | +------------------------------+ 1 row in set, 1 warning (0.00 sec) mysql> Select TIMEDIFF('2017-10-22 04:05:45', '2017-09-01 03:05:45')AS 'Out of Range ...
Read MoreWhat would be the effect on MySQL output if we have the combination of NULL and other values in the list of strings, provided as arguments in FIELD() function?
There will be a significant change in the output if we have the combination of NULL and other values in the list of strings, provided as arguments in FIELD() function. Following example will demonstrate it Example mysql> Select FIELD('good', 'Ram', 'is', 'good', 'boy'); +---------------------------------------+ | FIELD('good', 'Ram', 'is', 'good', 'boy') | +---------------------------------------+ | 3 | +---------------------------------------+ 1 row in set (0.00 sec) ...
Read MoreWhat happens if a NULL argument is provided in MySQL CONV() function?
MySQL will return NULL as the output if any of the argument of CONV() function is NULL or if the value provided for the base is out of limit(i.e. not between minimum 2 and maximum 36). Following examples would demonstrate it. Example mysql> Select CONV(10,NULL,2); +-----------------+ | CONV(10, NULL,2)| +-----------------+ | NULL | +-----------------+ 1 row in set (0.00 sec) mysql> Select CONV(10,10, NULL); +------------------+ | CONV(10,10, NULL)| +------------------+ | NULL | +------------------+ 1 row in set (0.00 sec) mysql> Select CONV(NULL,10,2); +-----------------+ | CONV(null,10,2) | +-----------------+ | NULL | +-----------------+ 1 row in set (0.00 sec)
Read MoreWhat are the complexities MySQL joins involve?
Actually, in simple words, we can say that a join between tables is an extension of a single-table SELECT statement but it involves the additional complexities:Need to specify all the tablesWe need to specify all the tables in FROM clause which are involved in the join. It is in contrast with the SELECT statement in which only one table name is necessary.Need to specify the matching conditionsWe just need to specify the matching conditions based on which a join matches the records in one table with a record in another table. The conditions often are given in the WHERE clause, ...
Read MoreHow can I search data from MySQL table based on similar sound values?
With the help of SOUNDS LIKE operator, MySQL search the similar sound values from the table. Syntax Expression1 SOUNDS LIKE Expression2 Here, both Expression1 and Expression2 will be compared based on their English pronunciation of sound. Example Following is an example from ‘student’ table which will match the two expressions based on the pronunciation of sound mysql> Select Id, Name, Address, Subject from student where name sounds like 'hrst'; +------+---------+---------+----------+ | Id | Name | Address | Subject | +------+---------+---------+----------+ | 15 | Harshit | Delhi | Commerce | +------+---------+---------+----------+ 1 row in set (0.00 sec)
Read More