TO_DATE - Convert String to Datetime - Oracle to MySQL Migration

In Oracle, the TO_DATE function converts a string value to DATE data type value using the specified format.

In MySQL, you can use STR_TO_DATE function. Note that the TO_DATE and STR_TO_DATE format strings are different.

Oracle:

  -- Specify a datetime string literal and its exact format
  SELECT TO_DATE('2013-02-11', 'YYYY-MM-DD') FROM dual;

MySQL:

  -- Specify a datetime string literal and its exact format
  SELECT STR_TO_DATE('2013-02-11', '%Y-%m-%d');

When you convert Oracle TO_DATE function to STR_TO_DATE function in MySQL, you have to map the format specifiers:

Oracle TO_DATE		MySQL STR_TO_DATE
YYYY	4-digit year	%Y
SYYYY	4-digit year with a minus sign for BC dates	%Y
YY	2-digit year	%y
RRRR	2 or 4-digit year, 20th century for 00-49	%Y
RR	2-digit year, 20th century for 00-49	%y
MON	Abbreviated month (Jan - Dec)	%b
MONTH	Month name (January - December)	%M
MM	Month (1 - 12)	%m
DY	Abbreviated day (Sun - Sat)	%a
DD	Day (1 - 31)	%d
HH24	Hour (0 - 23)	%H
HH or HH12	Hour (1 - 12)	%h
MI	Minutes (0 - 59)	%i
SS	Seconds (0 - 59)	%s
SSSSS	Seconds past midnight (0-86399)	Use SEC_TO_TIME() function (see below)

Typical conversion examples:

In Oracle TO_DATE, the SSSSS format specifies the number of seconds past midnight:

Oracle:

  ALTER SESSION SET NLS_DATE_FORMAT = 'YYYY-MM-DD HH24:MI:SS';
 
  -- Convert 110 seconds to 1 minute and 50 seconds
  SELECT TO_DATE('110', 'SSSSS') FROM dual;
  /* 2025-12-01 00:01:50 */
 
  SELECT TO_DATE('2025-12-24 110', 'YYYY-MM-DD SSSSS') FROM dual;
  /* 2025-12-24 00:01:50 */

Note that if the date part is not specified it is set to the first day of the current month.

In MySQL, you can use the SEC_TO_TIME function to convert seconds to TIME:

MySQL:

  -- Seconds as string (microseconds as added)
  SELECT SEC_TO_TIME('110');
  /* 00:01:50.000000 */
 
  -- Seconds as integer
  SELECT SEC_TO_TIME(110);
  /* 00:01:50 */
 
  -- Get the same result as Oracle TO_DATE including the date part (the first day of the current month)
  SELECT CAST(CONCAT(SUBSTR(NOW(), 1, 8), '01 ', SEC_TO_TIME(110)) AS DATETIME);
  /* 2025-12-01 00:01:50 */

There are some TO_DATE use cases that may look odd at first, but they can still have meaning:

Oracle:

  ALTER SESSION SET NLS_DATE_FORMAT = 'DD-MON-RR';
 
  -- SYSDATE is already DATE, why TO_DATE is used?
  SELECT TO_DATE(SYSDATE, 'DD/MM/YYYY') FROM dual;
 
  -- SYSDATE has the time part, but after TO_DATE it became zero (!) 
  SELECT TO_CHAR(SYSDATE, 'HH24:MI:SS'), 
              TO_CHAR(TO_DATE(SYSDATE, 'DD/MM/YYYY'), 'HH24:MI:SS') FROM dual;
  /* 23:23:48      00:00:00 */

Note that in TO_DATE(SYSDATE, format) expression Oracle firstly converts SYSDATE to string (!) using NLS_DATE_FORMAT and then converts the string back to DATE using the TO_DATE format.

Important note: Oracle can still convert a string to a date successfully, even if the format specified in TO_DATE does not match, as long as the string matches NLS_DATE_FORMAT or some other supported formats:

Oracle:

  -- Format does not match, but Oracle still can convert successfully (!)
  SELECT TO_DATE('14-SEP-2025', 'DD/MM/YYYY') FROM dual;
  /* 14-SEP-25 */
 
  -- Does not match, but also recognized
  SELECT TO_DATE('14.SEP.2025', 'DD/MM/YYYY') FROM dual;
  /* 14-SEP-25 */

Note that STR_TO_DATE(NOW(), format) returns NULL in MySQL if the format does not match '%Y-%m-%d':

MySQL:

  SELECT STR_TO_DATE(NOW(), '%d/%m/%Y');
  /* NULL */
  /* 1 warning */
 
  SHOW WARNINGS;
  /* Warning | 1411 | Incorrect datetime value: '2025-09-16 19:52:34' for function str_to_date */
 
  SELECT STR_TO_DATE(NOW(), '%Y-%m-%d');
  /* 2025-09-16 */

For more information, see Oracle to MySQL Migration.