Please help with a query

[UBfoolin]

I can not figure out how to do this in MySQL 4.0.12.

The rule is, in English, if an account has a Code1 then it should not have a Code2. I need to find all of the T1.Code values that break this rule.

Table1 (T1) [50,000 accounts; Approx 20 codes per acct]
Account
Code

Table2 (T2) Has 200,000 records
Code1
Code2

I need to get all accounts where one of T1.Code matches a T2.Code1 value, and the same T1.Account has another T1.Code that matches a T2.Code2 value.

I specifically need the T1 record where T1.Code = T2.Code2. The final recordset will be only these records.

I have no restrictions on how to accomplish this. Temp tables are ok. Needs to be fairly quick though.

All help is greatly appreciated!
Thank you.

 

[UBfoolin]

I think I may have been unclear in my request above. T2 can have a specific Code1 value several times with various Code2 values.

An example:
T1
Account Code
123 A
123 B
123 4
123 8

T2
Code1 Code2
B A
B Y
B 1
B 4

I want to end up with all records, for each account, where T1.Code(Value1)=T2.Code2 and T1.Code(Value2)=T2.Code1. In the example above, the result would be:
Acct=123, Code=4, Code1=B, Code2=4.

In other words, once a T1.Code match is made with T2.Code1, if there is another T1.Code match with T2.Code2, select the record.
Hope this helps.