When Does oracle use the to_date function?

First, let's take A look at the data type. For comparison, use the> =; for comparison, use the to_date function to convert the data type of field B, and specify the format as needed;
A LOGON_TIME DATE
B KPI_VALUE VARCHAR2 (400)
The following are specific comparison statements:
Select count (*) from C where A> = '2017-07-01 'and DATE_TIME <= '2017-08-03 ';
Select count (*) from D where B> = to_date ('20140901', 'yyyymmdd') and date_time <= to_date ('20140901', 'yyyymmdd ');
 
 
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