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Suppose if we want the output of FROM_UNIXIME() function in a particular format then we can use date format string or time format string or both in it. Following is the example of using the format string in FROM_UNIXTIME() function −mysql> Select FROM_UNIXTIME(1555033470 '%Y %M %D')AS 'Formatted Output'; +------------------+ | Formatted Output | +------------------+ | 2019 April 12th | +------------------+ 1 row in set (0.00 sec)In the query above, it is using only date format string.mysql> Select FROM_UNIXTIME(1555033470 '%h:%i:%s')AS 'Formatted Output'; +------------------+ | Formatted Output | +------------------+ | 07:14:30 | +------------------+ 1 row in set (0.00 ... Read More
In that case, MySQL returns the Unix timestamp of the current date and time. Hence we can say that using no argument is same as using NOW() as an argument to UNIX_TIMESTAMP() function.For example, if we run the query for UNIX_TIMESTAMP() with no value and with NOW() as an argument that MySQL returns the same result.mysql> Select UNIX_TIMESTAMP(); +------------------+ | UNIX_TIMESTAMP() | +------------------+ | 1509405559 | +------------------+ 1 row in set (0.00 sec) mysql> Select UNIX_TIMESTAMP(NOW()); +-----------------------+ | UNIX_TIMESTAMP(NOW()) | +-----------------------+ | 1509405559 | +-----------------------+ 1 row in set (0.00 sec)The ... Read More
Aural rendering of documents is mainly used by the visually impaired. The following are the aural media CSS properties −The azimuth property sets, where the sound should come from horizontally.The elevation property sets, where the sound should come from vertically.The cue-after specifies a sound to be played after speaking an element's content to delimit it from other.The cue-before specifies a sound to be played before speaking an element's content to delimit it from other.The cue is a shorthand for setting cue-before and cue-after.The pause-after specifies a pause to be observed after speaking an element's content.The pause-before specifies a pause to be observed ... Read More
Aural rendering of documents is mainly used by the visually impaired. Some of the situations in which a document can be accessed by means of aural rendering rather than visual rendering are the following.Learning to readTrainingWeb access in vehiclesHome entertainmentIndustrial documentationMedical documentationWhen using aural properties, the canvas consists of a three-dimensional physical space (sound surrounds) and a temporal space (one may specify sounds before, during, and after other sounds).
As we know that GROUP BY clause in a SELECT statement can divide the result set, returned by MySQL, in groups. Now if we want to return only some specific groups then need to apply filtering criteria at the group level. It can be done by using HAVING clause inside the GROUP BY clause. The example below will demonstrate it −ExampleSuppose we want to return only the group which is having an average salary of 55000 then we need to use filtering criteria as follows in HAVING clause −mysql> Select count(*), AVG(salary), Designation from employees GROUP BY designation having AVG(salary) ... Read More
It can be done by using GROUP BY clause in the SELECT statement. We can specify a column as grouping criteria with the help of GROUP BY clause. Due to the specified grouping criteria, rows with the same value in a particular column are considered as a single group. In this way, the result set returned by MySQL SELECT statement will be divided into groups.ExampleFollowing is a good example to understand it −We have a table named ‘employees’ as follows −mysql> Select * from employees; +------+-------------+--------+------------+ | id | designation | Salary | DoJ | +------+-------------+--------+------------+ ... Read More
MySQL converts Unix timestamp to timestamp data type value with the help of FROM_UNIXTIME() function.Examplemysql> Select FROM_UNIXTIME(1508622563); +-----------------------------+ | FROM_UNIXTIME(1508622563) | +-----------------------------+ | 2017-10-22 03:19:23 | +-----------------------------+ 1 row in set (0.00 sec)
When we pass an out-of-range value in UNIX_TIMESTAMP, MySQL returns 0. The valid range of value is same as for the TIMESTAMP data type.Examplemysql> Select UNIX_TIMESTAMP('1969-01-01 04:05:45'); +---------------------------------------+ | UNIX_TIMESTAMP('1969-01-01 04:05:45') | +---------------------------------------+ | 0 | +---------------------------------------+ 1 row in set (0.00 sec)When we pass an out-of-range value in FROM_UNIXTIME, MySQL returns NULL. The valid range of values is same as for the INTEGER data type.Examplemysql> Select FROM_UNIXTIME(2147483648); +---------------------------+ | FROM_UNIXTIME(2147483648) | +---------------------------+ | NULL | +---------------------------+ 1 row in set (0.00 sec)
As we know that the value of timestamp can be converted to a number of seconds with the help of UNIX_TIMESTAMP() function. MySQL would ignore the microseconds added to the value of timestamp because the value of UNIX_TIMESTAMP is only 10digits long.Examplemysql> SELECT UNIX_TIMESTAMP('2017-10-22 04:05:36')AS 'Total Number of Seconds'; +-------------------------+ | Total Number of Seconds | +-------------------------+ | 1508625336 | +-------------------------+ 1 row in set (0.00 sec) mysql> SELECT UNIX_TIMESTAMP('2017-10-22 04:05:36.200000')AS 'Total Number of Seconds'; +-------------------------+ | Total Number of Seconds | +-------------------------+ | 1508625336 | +-------------------------+ ... Read More
We have to use GROUP BY clause if we want to use group functions with non-group fields in the SELECT query. The general syntax can be as followsSyntaxSELECT group_function1, …, non-group-column1, … from table_name GROUP BY column_name;Examplemysql> Select COUNT(*), id from Student GROUP BY id; +----------+------+ | COUNT(*) | id | +----------+------+ | 1 | 1 | | 1 | 2 | | 1 | 15 | | 1 | 17 | | 1 | 20 | +----------+------+ 5 ... Read More