Oracle functions integrate small example date operations

Oracle Function Synthesis small example date operation premise there is a student table student contains a birthday field (Date Field) let you find a student over 10 years old. Here, we only use the year to judge the difference between the birthday and the current date. First, we need to convert the date type into a string, to_char (obj, formart) to_char (birthday, 'yyyymmdd') is converted into to_date (str, formart) to_date (sysdate, 'yyyy-mm-dd ') obtain the year substr (str, start index, truncation length) substr (to_char (birthday, 'yyyymmdd )) convert string to number to_number function to number to_number (substr (to_char (birthday, 'yyyymmdd ))) final sqlselect * from student where birthday is not null and (to_number (substr (to_char (sysdate, 'yyyymmdd'),)-to_number (substr (to_char (birthday, 'yyyymmdd'), 0, 4)> 10