How to lock a row in a db2/400

Hi all,
Could someone show me how to lock a row in the database DB2/400
The scenario:
DB.beginTransaction
User 1 gets a row with a column bill_number
"select bill_number from numbers where pk = xxx for update"
aux_bill_number = bill_number
USER 1 updated this row
"update numbers set bill_number = bill_number +1 where pk = xxx "
USER 1, like final step, insert aux_bill_number in other table as primary key
DB.commitTransaction
While doing so,
User 2 also gets a row with a bill_number. this user must take bill_number with value 2, but take the same value 1
This it causes key duplicated in the destiny table.
Please, help me.
How I must lock the row not to allow to read until finishing the previous transaction?

Hi all,
Could someone show me how to lock a row in the
database DB2/400Isn't SELECT FOR UPDATE standard?
>
The scenario:
DB.beginTransaction
er 1 gets a row with a column bill_number
"select bill_number from numbers where pk =
xxx for update"
aux_bill_number = bill_number
1 updated this row
"update numbers set bill_number = bill_number
+1 where pk = xxx "
USER 1, like final step, insert aux_bill_number in
other table as primary key
DB.commitTransactionSounds like you're trying to do something that a JOIN would do better.
While doing so,
User 2 also gets a row with a bill_number. this user
must take bill_number with value 2, but take the
same value 1
This it causes key duplicated in the destiny table.
Please, help me.
How I must lock the row not to allow to read until
finishing the previous transaction?Setting the isolation level to SERIALIZABLE might help.
%

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Hi,
I want few suggestion in the following scenario .
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How to lock a row in a db2/400

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