5.11.1 Problem
You have a time value but you want a value in seconds, or vice versa.
5.11.2 Solution
TIME values are specialized representations of a simpler unitsecondsand you can convert back and forth from one to the other using TIME_TO_SEC( ) and SEC_TO_TIME( ).
5.11.3 Discussion
TIME_TO_SEC( ) converts a TIME value to the equivalent number of seconds, and SEC_TO_TIME( ) does the opposite. The following query demonstrates a simple conversion in both directions:
mysql> SELECT t1, -> TIME_TO_SEC(t1) AS 'TIME to seconds', -> SEC_TO_TIME(TIME_TO_SEC(t1)) AS 'TIME to seconds to TIME' -> FROM time_val; +----------+-----------------+-------------------------+ | t1 | TIME to seconds | TIME to seconds to TIME | +----------+-----------------+-------------------------+ | 15:00:00 | 54000 | 15:00:00 | | 05:01:30 | 18090 | 05:01:30 | | 12:30:20 | 45020 | 12:30:20 | +----------+-----------------+-------------------------+
To express time values as minutes, hours, or days, perform the appropriate divisions:
mysql> SELECT t1, -> TIME_TO_SEC(t1) AS 'seconds', -> TIME_TO_SEC(t1)/60 AS 'minutes', -> TIME_TO_SEC(t1)/(60*60) AS 'hours', -> TIME_TO_SEC(t1)/(24*60*60) AS 'days' -> FROM time_val; +----------+---------+---------+-------+------+ | t1 | seconds | minutes | hours | days | +----------+---------+---------+-------+------+ | 15:00:00 | 54000 | 900.00 | 15.00 | 0.62 | | 05:01:30 | 18090 | 301.50 | 5.03 | 0.21 | | 12:30:20 | 45020 | 750.33 | 12.51 | 0.52 | +----------+---------+---------+-------+------+
Use FLOOR( ) if you prefer integer values to floating-point values:
mysql> SELECT t1, -> TIME_TO_SEC(t1) AS 'seconds', -> FLOOR(TIME_TO_SEC(t1)/60) AS 'minutes', -> FLOOR(TIME_TO_SEC(t1)/(60*60)) AS 'hours', -> FLOOR(TIME_TO_SEC(t1)/(24*60*60)) AS 'days' -> FROM time_val; +----------+---------+---------+-------+------+ | t1 | seconds | minutes | hours | days | +----------+---------+---------+-------+------+ | 15:00:00 | 54000 | 900 | 15 | 0 | | 05:01:30 | 18090 | 301 | 5 | 0 | | 12:30:20 | 45020 | 750 | 12 | 0 | +----------+---------+---------+-------+------+
If you pass TIME_TO_SEC( ) a date-and-time value, it extracts the time part and discards the date. This provides yet another means of extracting times from DATETIME and TIMESTAMP values (in addition to those already discussed earlier in the chapter):
mysql> SELECT dt, -> TIME_TO_SEC(dt) AS 'time part in seconds', -> SEC_TO_TIME(TIME_TO_SEC(dt)) AS 'time part as TIME' -> FROM datetime_val; +---------------------+----------------------+-------------------+ | dt | time part in seconds | time part as TIME | +---------------------+----------------------+-------------------+ | 1970-01-01 00:00:00 | 0 | 00:00:00 | | 1987-03-05 12:30:15 | 45015 | 12:30:15 | | 1999-12-31 09:00:00 | 32400 | 09:00:00 | | 2000-06-04 15:45:30 | 56730 | 15:45:30 | +---------------------+----------------------+-------------------+ mysql> SELECT ts, -> TIME_TO_SEC(ts) AS 'time part in seconds', -> SEC_TO_TIME(TIME_TO_SEC(ts)) AS 'time part as TIME' -> FROM timestamp_val; +----------------+----------------------+-------------------+ | ts | time part in seconds | time part as TIME | +----------------+----------------------+-------------------+ | 19700101000000 | 0 | 00:00:00 | | 19870305123015 | 45015 | 12:30:15 | | 19991231090000 | 32400 | 09:00:00 | | 20000604154530 | 56730 | 15:45:30 | +----------------+----------------------+-------------------+
Using the mysql Client Program
Writing MySQL-Based Programs
Record Selection Techniques
Working with Strings
Working with Dates and Times
Sorting Query Results
Generating Summaries
Modifying Tables with ALTER TABLE
Obtaining and Using Metadata
Importing and Exporting Data
Generating and Using Sequences
Using Multiple Tables
Statistical Techniques
Handling Duplicates
Performing Transactions
Introduction to MySQL on the Web
Incorporating Query Resultsinto Web Pages
Processing Web Input with MySQL
Using MySQL-Based Web Session Management
Appendix A. Obtaining MySQL Software
Appendix B. JSP and Tomcat Primer
Appendix C. References