Q:

Can someone figure out the encryption method? 

Is there a way to decrypt a database if I know the encrypted and decrypted state of the data?  We have old software at work (VB) that needs rewriting, problem is that the database is encrypted.  I can query the old software for individual entries, and see the corresponding encrypted data in the DB, but the database is about 1000 entries long and I wouldn't want to do this by hand.  I can give you some examples: 
Unencrypted Data   Corresponding encrypted data
0264/592636        /2Q0Z3MfVTGAgILN2krVfmp+lYs=
0264/591410        /2Q0Z3MfVTGAlWGWetMmvNarF6s=
0264/591548        /2Q0Z3MfVTGAlWNdmW96pgsiQxE=
0264/402559        /2Q0Z3MfUzia9nqAJug5dVxNbto=
0364/888890        /2Q0Z3MfakAgSr1LCbMmjJ6D6tM=

A:

There are three solutions here:

Try to find the encryption method.  It can be something custom, it can be encrypted in all sorts of weird ways, and you might need a key from somewhere.  This is what you are trying to do now. 
Find the code that encrypts/decrypts the data. 
Write a script that simply calls the decrypt function for all records. 

I'm not sure which is easier, 2 or 3, but trying to figure out what kinda code this is doesn't seem like the way to go. 
Moreover, this is a problem specifically for you.  It's not useful for future readers if it was solved using solution 1, thus the question would be closed as too localized. 
I don't know why you didn't try solution 2 actually, can't you read VB well enough to find it or so?  I don't mean it accusing, but if you can't find the code or script something to fix it (solution 3), you might want to find someone who can.  It would probably save you (and anyone trying to find what encryption it is) a lot of time.