MySQL time and date

Datetime occupies 8 bytes to display the date and display the time yyyy-mm-dd hh: mm: SS display range 1000-01-01 00:00:00 ---- 9999-12-31 23:59:59 available format/01/01 00 + 01 + 102011010100011011/01/01/00 @ 01@10mysql5.5 versions earlier date type cannot be accurate to microsecond level date occupies 3 bytes display date display range: 1000-01-01----9999-12-31 timestamp occupies 4 bytes 1970 10 10 80001----2038-01-19 03: 14: 07 The timestamp and datetime display results are the same but the display range is different. You can set the default value in the timestamp format when creating a table, if datetime does not update the table, you can set the columns of the timestamp type to automatically update to the current time-838: 59: 59 ---- 838: 59: 59 year can use year (2) and year (4) time-related functions Now current_timestamp sysdate 1. Now and current_timestamp are the same 2. The sysdate function returns the time when the current function is executed, and the time when the now function returns the SQL statement. Time addition and subtraction If the target year is a leap month, the system automatically adds or subtracted one day. Date_add (date, interval expr unit) date_sub (date, interval expr unit) date_add (now (), interval 1 day) unit can be the following data: yearmonthdayweekhourminutesecondmicrosecond date_format () function, the function is to format and print the date as required by the user. If the query condition is used, we recommend that you use the time index. Select Date_format (now (), '% Y % m % D ') As datetime;