serious error JDBC sender channel

Hi in a JDBC---- > XI -----> proxy scenario,

i select some rows from a table, from a sender JDBC channel,

and in the BPM, i make a synchronous call to the same DATABASE using JDBC receiver channel, and then send it to R/3 using proxy,

the problem is:

in the sender JDBC channel,

Query SQL Satement: select * from mytable where status = 0;

Update SQl Statement: update mytable set status = 1 where status =0,

my query is, in the sender JDBC channel, whether both queries occur as a transaction, are the two quries ATOMIC? means, do the response is given back only after both quries happen completely,

becoz i want to process further steps only after Update(in the sender JDBC channel) also happens,

because the next step is a sync Send to the same dataabse table, so is there a possibility that the sender channel sends the selected row(select query happens), and the Update query keeps happening in the background, and in the mean time, the second step, i.e., the sync JDBC send, also happens ?