In Oracle SQL Developer, the ADD_MONTHS function is a versatile tool that allows you to add or subtract months from a date value. This is particularly useful when working with dates that occur at different intervals, such as monthly billing cycles or employee pay periods.
To subtract a number of months from a date column, simply use the following syntax:
```sql SELECT ADD_MONTHS(date_column, -number_of_months_column) FROM table_name; ```For example, the following query would subtract 3 months from the invoice_date column in the invoices table:
The result of this query would be a new column called discounted_invoice_date that contains the invoice date minus 3 months.
It's important to note that the ADD_MONTHS function will handle cases where there is no corresponding date in the target month. For instance, if you subtract 1 month from February 29th, the result will be January 28th, not January 31st.
If you're working with dates that always occur in every month, such as the first day of the month, you can also use a fixed interval to subtract months. The following query achieves the same result as the previous one, but it's more efficient because it doesn't need to handle cases where there's no corresponding date:
```sql SELECT date_column - number_of_months_column * INTERVAL '1' MONTH FROM table_name; ```Whichever method you choose, the ADD_MONTHS function is a powerful tool that can help you easily manipulate dates in Oracle SQL Developer.