Oracle Time query

The Oracle query date can use =, but the data types must be consistent on both sides of the equal sign,

For example, '2014-9-19 'is a string that cannot be directly compared with a date field and must undergo date conversion:

Convert date to string to_char (date, 'yyyy-mm-dd') = '2017-09-19'

Convert a string to the date to_date ('1970-9-19 ', 'yyyy-mm-dd') = trunc (date) date may contain time, minute, and second. Note that

1. query the time value of a time field.

Select count (*) from t_date_table where to_char (c_time, 'yyyy-mm-dd') = '2017-03-28 ';

2. query the statistical value within a certain time range

Select count (*) from t_date_table where c_timee between to_date ('2017-03-26 ', 'yyyy-MM-DD') and to_date ('2017-03-28 ', 'yyyy-MM-DD ');