Python sqlite3 generate unique identifier

Question

I am trying to add values to a 'pending application table'. This is what I have so far:

    appdata = [(ID,UNIQUE_IDENTIFIER,(time.strftime("%d/%m/%Y"),self.amount_input.get(),self.why_input.get())]

    self.c.execute('INSERT into Pending VALUES (?,?,?,?,?)', appdata)
    self.conn.commit()

I need to set a value for 'UNIQUE_IDENTIFIER', which is a primary key in a sqlite database.

How can I generate a unquie number for this value?

CREATE TABLE Pending (
    ID          STRING REFERENCES StaffTable (ID),
    PendindID   STRING PRIMARY KEY,
    RequestDate STRING,
    Amount      TEXT,
    Reason      TEXT
);

That would be good, I am new to sqlite and I am unsure how to do it correctly though — Mathew Wright
– Mathew Wright, Commented Oct 21, 2016 at 10:31

Hisham Karam · Accepted Answer · 2016-10-21 13:01:25Z

2

two ways to do that:

1-First

in python you can use uuid module example:

>>> import uuid
>>> str(uuid.uuid4()).replace('-','')
'5f202bf198e24242b6a11a569fd7f028'

note : a small chance to get the same str so check for object exist with the same primary key in the table before saving

this method uuid.uuid4() each time return new random

for example:

>>> ID=str(uuid.uuid4()).replace('-','')
>>>cursor.execute("SELECT * FROM Pending WHERE PendindID = ?", (ID,))
>>>if len(data)==0:
      #then save new object as there is no row with the same id
   else:
       #create new ID

2-second

in sqlite3 make a composite primary key according to sqlite doc

CREATE TABLE Pending (
  column1, 
  column2, 
  column3, 
  PRIMARY KEY (column1, column2)
);

Then make sure of uniqueness throw unique(column1, column2)

edited Oct 21, 2016 at 13:01

answered Oct 21, 2016 at 11:22

Hisham Karam

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5 Comments

Mathew Wright Over a year ago

How can i generate a new id, then check if the id is already used?

Mathew Wright Over a year ago

thanks, that is a lot of help! But, can you explain what 'data' is. And, am i right to assume that if len(data)==0

Mathew Wright Over a year ago

If len(data) ==0, then the database search returned no IDs that matched to generated ID?

Hisham Karam Over a year ago

@MathewWright yes exactly data is the queryset if it's length zero the no ids matches generated id

Hisham Karam Over a year ago

@MathewWright you are welcome, mark the answer if it was correct .

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