Mongodb uses the forEach and js custom functions to modify the 19th character of the specified column
The following is the test:
Db.csq.insert ({alm:'11110000011111100011110111010110'})
Db.csq.insert ({alm:'01110000011111100011110111010110'})
Db.csq.insert ({alm:'11111111111111111111111111111111'})
Db.csq.find () .forEach (function (e) {
E.alm = e.alm.substr (0jue 19) +'0' + e.alm.substr (20jue 12)
Db.csq.save (e)
});
