comparing byte arrays

[eoghan.kenny]

Hi,

I need to compare two timestamp columns in sql server and see which one
is greater. (i can tell if they are not equal buts not enough for this
requirement).

A timestamp value is unique in a database and always increments. A
non-null timestamp is type Binary(8) in sql server and I pass it to a
byte array in C#. To compare the two byte arrays I use
BitConverter.ToUInt64, as this converts an 8 byte array to a 64 bit
integer. I can then compare the two integers to see which is greater.

Is this method of comparing byte arrays correct ?

Thanks.

 

[Truong Hong Thi]

The SqlBinary class provides many methods/operators (like equality
operator and Equals method) which you can use.
SqlDataReader.GetSqlBinary() return SqlBinary.

 

[ek1]

thats a good tip about the sqlbinary type, i hadn't thought of that.
However it doesn't seem to help me determine which timestamp or byte
array is the greater, only if they are or are not equal.

one other way i have seen this done is to compare the timestamps using
SQL, but I want to to this in my C# program.

 

[Truong Hong Thi]

However it doesn't seem to help me determine which timestamp or byte

array is the greater

It does, in fact:
if (binary1 > binary2) {}
You can even do like this:
if (binary1 >= binary2) {}
Same for ==, <, <=. SqlBinary has overloads all of these operators.
Just see its member in MSDN.

Of course, you can also use binary.CompareTo(binary2)

 

[ek1]

yes you're correct, thanks for your help !