SQL Server: round decimal number and convert to int (within Select)

You can use ROUND function to round the value to integer:

ROUND(INT, 100 * AVG(CASE WHEN col2 = col3 THEN 1.0 ELSE 0.0 END), 0) AS matchPercent

This will retain the type, e.g rounded float will stay float. If you also need to return int data type (or other integer data types), you need to also convert it:

CONVERT(INT, ROUND(INT, 100 * AVG(CASE WHEN col2 = col3 THEN 1.0 ELSE 0.0 END), 0)) AS matchPercent

Use the round function to round the number:

ROUND(100 * AVG(CASE WHEN col2 = col3 THEN 1.0 ELSE 0.0 END), 0) AS matchPercent

If you want to round the number first and then convert it to an integer, you also can add 0.5 to the number that you want to convert to an integer.