How to SUM Bit Fields in SQL
By default, SQL Server doesn’t allow an operation like this:
SELECT SUM(blnBitColumn) FROM tblTable;
In order to achieve this result, you must first convert the bit column to a numeric type:
SELECT SUM(CONVERT(int,blnBitColumn)) FROM tblTable;
This counts the number of times the bit is true.
If you want to get the flip-side of that to see how many times the bit is false, just subtract the total number of bits from the positive:
SELECT COUNT(blnBitColumn)-SUM(CONVERT(int,blnBitColumn)) FROM tblTable;