How to Convert String value into date format - mysql

This is my string value 20180421
I want to convert this value into 2018/04/21
here my code
$querya="SELECT STR_TO_DATE('$date','%m/%d/%Y');";
but i does not change my string

Your format is already in ISO format, so you can just use date() for the conversion:
select date(?)
You can also use str_to_date() but you need to use the correct format:
$querya = "SELECT STR_TO_DATE(?, '%Y%m%d')";
Note the use of ?. This is a parameter placeholder and indicates that you should pass the value in as a parameter rather than as a variable.
I should point out that 2018/04/21 is a particular format. Dates are stored in an internal format. To get a particular output format, you need to convert them to strings. Here is one solution:
select date_format(date(?), '%Y/%m/%d')
The date() function is optional, because MySQL will correctly convert this string to a date, so you can also use:
select date_format(?, '%Y/%m/%d')

Related

MySQL equivalent of php's strtotime()

Is there a way to convert a string such as "-1 week" or "-5 minutes" into a datetime value in MySQL similar to php's extremely convenient strtotime() function?
I have a table that stores a human-readable time interval (such as "2 minutes") in one column and a datetime in another column.
I would like to select the rows where more than the amount of time specified in interval has elapsed since datetime.
MySQL doesn't have an equivalent of PHP's strtotime() in the sense that there is nothing that will automatically attempt to parse and determine the format of a date string using by assuming multiple formats.
What it does have is STR_TO_DATE(str,format) which requires you specify the format of your date, time or date + time string. It is the equivalent of PHP's date_create_from_format(format, str) function (though the format of the format parameter are different).
Here are some examples given from the MySQL documentation. They show a date being passed along with the format string that lets it know how the date string is to be interpreted:
SELECT STR_TO_DATE('01,5,2013','%d,%m,%Y');
SELECT STR_TO_DATE('May 1, 2013','%M %d,%Y');
Alternatively, you can cast a string to a date, time or datetime type, but they require a specific format (YYYY-MM-DD hh:mm:ss.fraction) for it to work:
SELECT CAST("2019-11-21" AS DATE);
If you deviate too far from that format it will make a few assumptions but could produce an incorrect date.

Convert any valid date format to date in mysql

How can we check if a string is a valid date without specifying the format in MySQL.A user may enter below formats;
21-08-2013
21/08/2013
2013/08/21
21jan2018
I don't know the format in advance which a user may enter.
I tried :
Select str_to_date() but here I need to specify format which I don't want.
I just want to check if a string is valid date without specifying the format.
Please suggest.
Thanks
All four of the date strings you showed us in the question can be converted to a MySQL date using STR_TO_DATE with an appropriate format mask. So, you should be able to simply check for these date patterns, if all you want is to know if you could convert them to dates:
SELECT *
FROM yourTable
WHERE
col REGEXP '[0-9]{2}-[0-9]{2}-[0-9]{4}' OR
col REGEXP '[0-9]{2}/[0-9]{2}/[0-9]{4}' OR
col REGEXP '[0-9]{4}/[0-9]{2}/[0-9]{2}' OR
col REGEXP '[0-9]{2}[A-Z]{3}[0-9]{4}';

extract month from mysql

How can I extract the month with a sql query in mysql.
The date format is as follows: dd/mm/yyyy.
MONTH(datecol) = $month // this does not work.
However if I change the date format to yyyy-mm-dd it works, but this is not an option.
You can parse a date in any format into an SQL date value with str_to_date. For example:
select month(str_to_date('25/07/2013', '%d/%m/%Y'));
This expression will extract the portion of the string that appears between the first and second forward slashes.
SUBSTRING_INDEX(SUBSTRING_INDEX( '25/07/2013' ,'/',2),'/',-1)
will return '07'
To get this converted to a numeric, add zero to it,
SUBSTRING_INDEX(SUBSTRING_INDEX( '25/07/2013' ,'/',2),'/',-1) + 0
will return a numeric value of 7
NOTES
This expression will work with any string value, not just strings representing a valid date in the specified format. For example:
SUBSTRING_INDEX(SUBSTRING_INDEX( 'dd/mm/yyyy' ,'/',2),'/',-1)
will return 'mm'
If only one slash is found in the string, this will return the portion following the slash. If no slashes are found in the string, this will return the entire string.
If your intent is to validate that the string represents a valid date value, in the specified format, then the STR_TO_DATE() function can be used to convert the string to a DATE. The return from that expression can be used as an argument to any of the MySQL functions that take a DATE argument, such as the MONTH() function in your sample question.

Cannot get my format for date from string

I am not able to process my date format from inputs of dates like Jan-05-1975 , Kindly let me know what is wrong with following sql query. I want the format from the input to be in dd-mm-yyyy
Select STR_TO_DATE ('Jan-05-1975','%e-%b-%Y')
OR
Select DATE_FORMAT ('Jan-05-1975','%e-%b%-Y')
Since you are passing in a string initially, you should convert it to a date first, then convert to the format you want. This uses both STR_TO_DATE() and then DATE_FORMAT():
Select Date_Format(STR_TO_DATE('Jan-05-1975','%b-%d-%Y'),'%d-%m%-%Y');
See SQL Fiddle with Demo
The STR_TO_DATE converts your current string in your format to a date value, then the DATE_FORMAT converts it to the preferred format of dd-mm-yyyy

Why i got null from this query

Following is my sql query kindly let me know why is it returning null
Select STR_TO_DATE ('11-APR-74','%e%b%Y')
OR
Select DATE_FORMAT ('11-APR-74','%e%b%Y')
From MySQL STR_TO_DATE function:
The server scans str attempting to match format to it. ... Scanning
starts at the beginning of str and fails if format is found not to
match.
This is why your first query fails: 11-APR-74 does not look like %e%b%Y, so date cannot be parsed. You should do instead
SELECT STR_TO_DATE ('11-APR-74','%e-%b-%Y')
From MySQL Date and Time types:
Although MySQL tries to interpret values in several formats, date
parts must always be given in year-month-day order (for example,
'98-09-04'), rather than in the month-day-year or day-month-year
orders commonly used elsewhere (for example, '09-04-98', '04-09-98').
This is why your second query fails: 74 is not a valid day of month, you should do instead
SELECT DATE_FORMAT ('74-APR-11','%e%b%Y')
Note, that DATE_FORMAT is usually used on DB values, not string literals as you do - to get an output different from the default one.
If you want to convert from string to date
Select STR_TO_DATE ('11-APR-74','%d-%b-%y')
use it like ::
Select STR_TO_DATE ('11-APR-74','%e-%b-%Y')
Because '%e%b%Y' format does not correspond to '11-APR-74' string value (as STR_TO_DATE function expects), and because '11-APR-74' value is of type CHAR, but not DATETIME (as DATE_FORMAT function expects).
If you want to reformat a date represented by a CHAR value, convert it from its original format to DATETIME first, and then convert it to a string of desired format:
SELECT DATE_FORMAT(STR_TO_DATE('11-APR-74','%e-%b-%Y'),'%e%b%Y');
By the way, you could strip dashes with a plain string sunction:
SELECT REPLACE('11-APR-74','-','');