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Sq lite module9


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Module 9 out of 9; SQLite training slides, databases, SQL, ERD, software design, database

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Sq lite module9

  1. 1. MODULE 9: SQLITE AND PYTHON (A BRIEF INTRODUCTION) SQL and Scripting Training (C) 2020-2021 Highervista, LLC 1
  2. 2. 2 TOPICS Introduction to Python and SQLite Import and Connect The Cursor and Methods within the Cursor 12/12/20 (C) 2020-2021 Highervista, LLC
  3. 3. INTRODUCTION TO PYTHON AND SQLITE SQL and Scripting Training 12/12/20 (C) 2020-2021 Highervista, LLC 3
  4. 4. 4 WORKING WITH SQLITE As you can see from working with SQLite’s CLI or a GUI like DB Browser for SQLite, maintaining a company’s database would take quite a bit of expertise and devoted time Using a programming language like Python (and others) can automate quite a bit of the tasks necessary to maintain the database In addition, with a programming language, you can (optionally) create a user-specific GUI for the company’s database 12/12/20 (C) 2020-2021 Highervista, LLC
  5. 5. 5 A NOTE ABOUT PYTHON Your next course will be about the Python Programming Language We will not be covering Python in any detail in this module Our goal with this module is to introduce general Python concepts, as they relate to SQLite More detail will be presented in the Python course, so please consider this module as a ‘conceptual’ (first pass) overview of Python and SQLite For the SQL assessment, Python will not be a part of the assessment 12/12/20 (C) 2020-2021 Highervista, LLC
  6. 6. 6 USING PYTHON Assuming that you have a database created (as we’ve done in this course), you will need to have the programming language (like Python) connect to the database. This ‘connection’ is the link between an existing database and the Python programming language. 12/12/20 (C) 2020-2021 Highervista, LLC
  7. 7. IMPORT AND CONNECT SQL and Scripting Training 12/12/20 (C) 2020-2021 Highervista, LLC 7
  8. 8. 8 What is Needed In Python, you will need the sqlite3 module (the same one that we used) The sqlite3 package is ‘imported’ into Python by the use of the import command. After sqlite3 is imported, a connection between Python and the specific sqlite3 database must be made so that Python can access the specific database. Python CONNECTING PYTHON TO AN SQLITE DATABASE
  9. 9. 9 ONCE CONNECTED – CURSOR ‘OBJECT’ Once the database is successfully connected to Python, a cursor object is established. A cursor object is a way that Python can perform actions on the database. Within the cursor object, there is an execute() method that allows actions to be performed on the Sqlite3 database. For example, the screen image shows the cursor connection and the ability through the connection to run a SELECT command. We’ve done quite a few SELECT commands in our course. Establish a connection, then use a cursor object. The execution of the SELECT moves the ‘result set’ from the query to a location where the data can be worked on by the Python program. 12/12/20 (C) 2020-2021 Highervista, LLC
  10. 10. 10 USING FETCHONE() Now that a SELECT command was executed (a SELECT *), we can get one specific row by using the fetchone() command. With fetchone(), we can make changes to the one item that we ‘fetched.’ Any changes to the fetched record can be made to the particular record by Python, based on the decisions in the program. fetchone() method call Results of fetchone() method call to example database 12/12/20 (C) 2020-2021 Highervista, LLC
  11. 11. 11 PYTHON Python can ‘seed’ (or set up) the connection and, within the cursor object, can also set up the particular methods that can be used to maintain the database. This avoids an individual who works daily with the company’s database from knowing the specifics about connection objects and methods. We leave this knowledge for the programmer to code, test and turn over to the user. 12/12/20 (C) 2020-2021 Highervista, LLC
  12. 12. THE CURSOR AND METHODS WITHIN THE CURSOR SQL and Scripting Training 12/12/20 (C) 2020-2021 Highervista, LLC 12
  13. 13. 13 USING THE FETCHALL() METHOD The fetchall() methods returns all records that can be worked on (modified) in the Python program. Depending on the database size, this can be a huge amount of data. For our example database, we have a smaller set of data. fetchall() method embedded within print command Result set 12/12/20 (C) 2020-2021 Highervista, LLC
  14. 14. 14 PYTHON, EXAMPLE INSERT OF 1 RECORD Python can be used to insert records into a specific Sqlite3 table. Here’s an example where records are inserted into the consumers table by Python (first line). The second line prints the record. Using the cursor, do an INSERT into a Sqlite3 table on a previously connected database. Results of the INSERT printed out. 12/12/20 (C) 2020-2021 Highervista, LLC
  15. 15. 15 PYTHON, EXAMPLE OF A LIST OF INSERTED RECORDS We can INSERT multiple records into the database using Python. Python used to set up multiple records that are INSERTed Print verification 12/12/20 (C) 2020-2021 Highervista, LLC
  16. 16. 16 COMMIT The cursor that is established between the Python program and Sqlite3 helps facilitate the work between the programming language and the database. The changes are not made until the transactions are committed. The commit() method is part of the connection object that was first setup to connect the database to the programming language. The commit() method of the connection object makes the data ‘persistent’ in the database. 12/12/20 (C) 2020-2021 Highervista, LLC
  17. 17. 17 VERIFYING THE COMMIT Once the Python program selects the data to be changed (modified or inserted), and the commit is completed successfully, you can use a tool like the DB Browser for SQLite to view the data on the database. 12/12/20 (C) 2020-2021 Highervista, LLC
  18. 18. PYTHON/SQLITE SUMMARY SQL and Scripting Training 12/12/20 (C) 2020-2021 Highervista, LLC 18
  19. 19. 19 PYTHON AND SQLITE SUMMARY You can connect an SQLite database to a Python program by using a connection object. The connection object sets up a cursor, where work by Python can be done on the database. The cursor has several ‘methods’ to get data from the database and to place data back into the database, once Python code is executed on the particular database. A commit is required to ensure that the changes are ‘persistent’ on the database. 12/12/20 (C) 2020-2021 Highervista, LLC
  20. 20. 20 REFERENCE McFarland, R. (2020). Published Articles: Ron McFarland. Retrieved December 03, 2020, from 12/12/20 (C) 2020-2021 Highervista, LLC
  21. 21. 21 INTRODUCTION Ron McFarland Technologist, Educator Source: Microsoft Images
  22. 22. 22 ABOUT THIS COURSE This course is distributed free. I use several sources. But importantly, I use the book noted on the next slide. If you are using these PowerPoints, please attribute Highervista, LLC and me (Ron McFarland). IN ADDITION, please attribute the author noted on the next slide, as the author’s textbook provides essential information for this course. Source: Microsoft Images
  23. 23. 23 INTRODUCTION This course is offered to you free. HOWEVER, please purchase the following book, as it is a primary resource for this course. I do not make any $ from this course or this book. So, since a handful of good content is derived from the following text, please support this author! Title: SQL Quickstart Guide Author: Walter Shields Available: Amazon, B&N, and through ClydeBank media website at: tech/sql-quickstart-guide