What is the purpose of the to_date function in SQL?

In SQL, the purpose of the to_date function is to convert a string to a date type. This function specifically takes two parameters: one is the string representing the date, and the other is the format of the date. The to_date function converts the string to a date type based on the specified format and returns a date object.

For example, suppose there is a string “2021-12-31” representing a date, you can use the to_date function to convert it to a date type as shown below:

SELECT TO_DATE('2021-12-31', 'YYYY-MM-DD') AS date_value;

The query will return a date object representing “2021-12-31”.

It is important to note that the second parameter of the to_date function is a format template used to specify the format of the date string. Special characters in the template (such as YYYY for a four-digit year, MM for a two-digit month, DD for a two-digit day, etc.) will be interpreted as the corresponding date parts. If the date string does not match the template or the format is not recognized, the to_date function will throw an error. Therefore, when using the to_date function, make sure that the provided date string matches the specified format.