join_database.py joins two database table created in python using sqlite3 module. For eg. if first database has columns (Id, Data, Time, col1, col2, col3) and second database has columns (Id, Data, Time, col4, col5, col6) then the output of join_database() will be database table containing columns (Id, Data, Time, col1, col2, col3, col4, col5, c…

join_database.py

import sqlite3 as lite
import sys

def join_database(database1Name, database2Name, database3Name):
  ''' Join two database 'database1Name' and 'database2Name' into database 'database3Name' '''
  
  con1 = lite.connect(database1Name)           # Connect to Database1
  con2 = lite.connect(database2Name)           # Connect to Database2
  con3 = lite.connect(database3Name)           # Connect to Database3

  con1.row_factory = lite.Row                  # For reading column names from Database1
  con2.row_factory = lite.Row                  # For reading column names from Database2

  con1_new = lite.connect(database1Name)       # Create new connection with Database1 for reading data
  con2_new = lite.connect(database2Name)       # Create new connection with Database2 for reading data

  with con1, con2, con3, con1_new, con2_new:
    cur1 = con1.cursor()                       # Get cursor from connection 1 (con1)
    cur2 = con2.cursor()                       # Get cursor from connection 2 (con2)
    cur3 = con3.cursor()                       # Get cursor from connection 3 (con2)
  
    cur1_new = con1_new.cursor()               # Get connection from connection 1_new (con1_new)
    cur2_new = con2_new.cursor()               # Get connection from connection 2_new (con2_new)
   
    cur1.execute("SELECT * FROM your_table_name")    # Select all column names from table your_table_name in Database1 (Why column names see line no. 11)
    cur2.execute("SELECT * FROM your_table_name")    # Select all column names from table your_table_name in Database2 (Why column names see line no. 12)
  
    row_1 = cur1.fetchone()           # Fetch column names from database1 table
    row_2 = cur2.fetchone()           # Fetch column names from database2 table
  
    columnNames = row_1.keys()        # Read column names from Database1
    
    for item in row_2.keys():         # Append column names from Database1 with Database2, including duplicate column names only once (See description)
      if item not in row_1.keys():
        columnNames.append(item)
  
    cur3.execute("CREATE TABLE IF NOT EXISTS your_table_name(Id INTEGER PRIMARY KEY, Date TEXT(10), Time TEXT(8))")    # You can change this line according to your needs
    
    for col in columnNames[3:]:
      cur3.execute("ALTER TABLE your_table_name ADD {} DOUBLE".format(col))  # You can change the data type(here it is DOUBLE) according to your needs
  
    cur1_new.execute("SELECT * FROM your_table_name")   # Select complete data at once from table your_table_name in database1
    cur2_new.execute("SELECT * FROM your_table_name")   # Select complete data at once from table your_table_name in database2
  
    rows1 = cur1_new.fetchall()      # Read all rows from Database1
    rows2 = cur2_new.fetchall()      # Read all rows from Database2
  
    rows1 = [r[1:] for r in rows1]   # Except first row in rows1 read all rows
    rows2 = [r[3:] for r in rows2]   # Except first three rows in rows2 read all rows
  
    rows = [r1 + r2 for r1, r2 in zip(rows1, rows2)]  #Combine each rows in rows1 and rows2 element wise
  
    ques = []                        # Use by sqlite for inserting into table
    
    ques = ["?"]*len(columnNames[1:])    # Generate list [?, ?, ?, ?,........till length equals length of columnNames[1:]
    ques = ",".join(ques)                # Generate string "?,?,?,?,?........"
    
    columnNames = ",".join(columnNames[1:])  # Generate string "col1, col2, col3............"
      
    for item in rows:                # Insert combined data into new Database3
      cur3.execute("INSERT INTO your_table_name({0}) VALUES ({1})".format(columnNames, ques), item)
      
if __name__ == '__main__':
  pass

what if the database is not created using the sqlite3 module?.Can you provide the code for the same.