Java: race conditions - is there a way to make sure multiple lines of code are executed together?

Question

I have a registration page that receives tokens, analyzes them and enters the user’s system if the parameters are applied.

Meanwhile, when I checked the token, by the time I removed the token from db, another user can use the same token to enter. is there any way to make sure that a certain range of lines of code will be executed without intervention, so I will not have a problem with the state of the race?

thank

Update

I have two servers.

• apache tomcat 6
• red5 v0.9 (free Java streaming media streaming and communication server)

I am writing a Facebook application.

The game itself is written in Adobe Flash Builder 2.

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Answer 5

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  DELETE FROM Tokens WHERE TokenID = < request-token >
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  INSERT INTO Session VALUES (sessionUUID, userID, loginTime,...)

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