How to solve the problem of data table query error when SQLite writes the registration function?

SQLite Data query error
Only the first time I create a data table can I successfully register my first account , All the following failed to register , The reason is that the judgment statement indicated by my red arrow is always true , So it's impossible to flag Change of （ I set flag The default is true, Only for false The data table is written only when , Otherwise, the registration fails ）, But I don't know why , There was no problem with my previous registration function , But I remember I didn't change the registration code and SQLite, After reading for a long time, I still haven't solved the problem , I don't know why