Lookup table

Hi. Looking for help with a lookup table. I have two tables with three fields each. Table a has a.code, a.amount and a.tax; a.code and a.amount having values already.
I have lookup table b with fields b.code, b.amount and b.tax.
I would like to lookup a.code and a.amount in b.code and b.amount and return the value of b.tax to a.tax.
Any ideas?


Found a workaround :-)