To convert a DATETIME field to an integer in SQL, you can use the DATEDIFF function to calculate the difference between the DATETIME value and a fixed date, such as January 1, 1970. This will give you the number of seconds between the two dates, which you can then convert to an integer.

Here’s an example SQL query that demonstrates how to do this:

SELECT CAST(DATEDIFF(second, '19700101', your_datetime_field) AS int) AS datetime_as_int
FROM your_table;

In this query, your_datetime_field is the name of the DATETIME field that you want to convert to an integer, and your_table is the name of the table that contains the field.

The DATEDIFF function is used to calculate the difference between the your_datetime_field value and the fixed date of January 1, 1970. The result is the number of seconds between the two dates, which is then cast to an integer using the CAST function.

The resulting output of the query will be a column of integers, where each integer represents the DATETIME value from your_datetime_field as the number of seconds since January 1, 1970.

Note that you can adjust the fixed date to any other date if you need to calculate the difference from a different starting point.