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Sq lite module5


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Module 5 out of 9; SQLite training slides, databases, SQL, ERD, software design, database

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Sq lite module5

  1. 1. MODULE 5: SQL AND SQLITE SQL and Scripting Training (C) 2020-2021 Highervista, LLC 1
  2. 2. 2 TOPICS Types of RDBMS systems Getting started with a database project (e.g., Capstone) SQL Concepts (DDL and DML starter) DDL Starter DML Starter Introducing SQLite Setting up the SQLite Environment DB Browser for SQLite Simple Commands in the SQLite CLI Preview Day 5 Afternoon Activities
  3. 3. TYPES OF RDBMS SYSTEMS SQL and Scripting Training
  5. 5. 5 GUI, SLI, OTHER Some RDBMSs are primarily graphic by design (GUI) – Think Microsoft Access. Most have a command-line interface too (CLI). SQLite is an RDBMS that has command-line interface (CLI). It also has a browser option (SQLite Browser and other browser-like tools available).
  6. 6. 6 DATABASE MANAGEMENT SYSTEM/SQL RDBMS SQL Engine SQLite SQL – 1 file .db MySQL SQL – complex file system PostgreSQL SQL – complex file system Oracle SQL – complex file system
  7. 7. SQL CONCEPTS (DDL AND DML STARTER) SQL and Scripting Training
  9. 9. 9 DDL, DML, AND DCL Category Description Examples Data definition language (DDL) A series of commands used to change the way data is stored in the database and/or alter its structure. ALTER COMMENT CREATE DROP RENAME TRUNCATE Data manipulation language (DML) A series of commands used to add and/or manipulate data within the existing database schema. INSERT UPDATE DELETE Data control language (DCL) Two commands used to allow or remove access and/or privileges to the database GRANT REVOKE
  10. 10. 10 A NOTE ON DATABASE VIEWS A VIEW is a virtual table displaying the results of an SQL statement. It can contain data from more than one table and runs when it′s accessed, so the data displayed is current. It’s useful if you want a user to be able to see specific data without having access to the entire database.
  11. 11. 11 CLI VS. GUI CLI: All commands (DDL and DML) can be entered into the command line. Tedious. GUI: We’ll use DB Browser for SQLite. As you make selections in the user interface, you can see the DDL/DML be created.
  12. 12. 12 COURSE FOCUS WITH SQLITE DDL (like CREATE database, etc.) DML (like SELECT commands, etc.) Views (restrict user’s view of the database) SQLite ‘.dot’ commands (‘support’ commands in SQLite, similar to other database packages)
  13. 13. DDL—STARTER SQL and Scripting Training
  14. 14. 14 DATA DEFINITION LANGUAGE (DDL) • You can either create DDL ″by hand″ (text) or, for some ER design tools, the DDL can be automatically created from the design. • Keep in mind that a complete Data Dictionary can serve as a basis for creating tables in the database. • There are other DDL commands that will assist you in creating the tables and altering the table structure.
  15. 15. 15 DDL STATEMENTS • CREATE: Used to create the database or its objects (like table, index, function, views, store procedure and triggers). • DROP: Used to delete objects from the database. • ALTER: Used to alter the structure of the database. • TRUNCATE: Used to remove all records from a table, including all spaces allocated for the records are removed. • COMMENT: Used to add comments to the data dictionary. • RENAME: Used to rename an object existing in the database. (Note: Command varies based on RDBMS.)
  16. 16. 16 SQL DDL CREATE
  17. 17. 17 SQL DDL DROP
  19. 19. DML—STARTER SQL and Scripting Training
  20. 20. 20 DATA MANIPULATION LANGUAGE (DML) • SELECT – Look for (query) • INSERT – Insert into a table UPDATE – Update existing info in a table • DELETE – Delete existing info in a table
  21. 21. 21 QUERY, STATEMENT, AND CLAUSE A query is a request (a question) that returns information from the database. An SQL statement is any valid piece of SQL code that is executed by the SQL engine. A clause is a subsection of a query containing at least one keyword and relevant information needed by the query (clause is a portion of a query).
  22. 22. 22 SQL DML SELECT Words in ALL CAPS are SQL keywords. A query can contain multiple clauses, each starting with a keyword.
  23. 23. 23 SQL DML SELECT
  27. 27. 27 SQL DML UPDATE
  30. 30. 30 SQL DML DELETE
  32. 32. 32 REVIEW OF SQL CONCEPTS A table is a two-dimensional grid of rows and columns that contain data. Logical and Physical database terms include ­ table (physical) = entity (logical) ­ field (physical) = attribute (logical) A database record is a row in a table or multiple rows in a table (with a unique primary key). Data can exist as a variety of different data types, such as strings of text, numbers, or special characters. Metadata describes the nature and format of the data, including any minimum/maximum character length or required numbers, letters, or special characters.
  33. 33. 33 REVIEW OF SQL CONCEPTS Relational databases can contain many tables. Each table in a relational database should have a primary key that serves as a unique identifier for a row in a given table. A foreign key is any column in a table that exists as a primary key in another table. The relationship between tables and their primary and foreign keys is called a database schema. A database schema can be shown visually by an ERD (Entity Relationship Diagram), which serves as a blueprint for a database.
  34. 34. 34 REVIEW OF SQL CONCEPTS There are a variety of relational database (RDBMS) products, including the Oracle database, Microsoft SQL Server, MySQL, IBM DB2, and SQLite. While they may differ somewhat in their interface, the fundamental SQL engine is essentially the same (not including extensions). The SELECT keyword is the most common SQL command used in SQL queries. SQL statements can contain multiple clauses that use different SQL keywords.
  35. 35. INTRODUCING SQLITE SQL and Scripting Training
  36. 36. 36 SQLITE INTRODUCTION SQLite is the most popular SQL engine in the world. This section of the course includes hands- on, real-world problem solving using ­ SQLite (the CLI portion) ­ SQLite (the GUI portion)
  37. 37. 37 USE CASE OF SQLITE DATABASE SQLite is likely used more than all other database engines combined. It is found in •Every Android device •Every iPhone and iOS device •Every Mac •Every Windows10 machine •Every Firefox, Chrome, and Safari web browser •Every instance of Skype
  38. 38. 38 FEATURES OF SQLITE •SQLite does not require a separate server process or system (serverless). •SQLite comes with zero-configuration, so no setup or administration are needed. •A complete SQLite database is stored in a single cross-platform disk file. •SQLite is self-contained, which means no external dependencies.
  39. 39. SETTING UP THE SQLITE ENVIRONMENT SQL and Scripting Training
  41. 41. 41 GAINING ACCESS TO SQLITE Using SQLite, users can create file-based databases that can be transported across machines, platforms, etc. The only thing needed to view or edit these databases is the SQLite command line program (downloads from SQLite website), or another tool capable of communicating with SQLite (SQLite browser)
  42. 42. DB BROWSER FOR SQLITE SQL and Scripting Training
  44. 44. 44 OPEN Once downloaded, open the DB Browser for SQLite. (Consider a shortcut for easy access.)
  45. 45. 45 CREATE A DATABASE USING DB BROWSER With the DB Browser, create a new database. Create a database for the Capstone, with your initials. For example, I’ve created a database named RM_AWS_CAPSTONE.
  46. 46. 46 CREATE A DATABASE USING DB BROWSER Since SQLite is one database file, it requires at least 1 table. Add TestTable (Table). Add a field Test_id, INTEGER, PK (Primary Key). Add a field Test_Desc, TEXT. Notice the SQL commands populated in the bottom pane.
  48. 48. COMMANDS IN THE SQLITE CLI: INTERACTIVE SQL and Scripting Training
  50. 50. 50 TASK: CREATE A DATABASE WITH 2 TABLES Follow along.
  51. 51. 51 CREATE A DATABASE Open terminal window and enter sqlite3 college.db This starts SQLite and opens college.db SQLite creates college.db, if not found
  52. 52. 52 CREATE A TABLE: STUDENT Note: Commands are not case sensitive. I will use UPPER CASE for commands/reserved words and lower case for fields. Note: commands are separated by commas and a line ends with ;
  53. 53. 53 CREATE A TABLE: STUDENT When there isn’t an error, sqlite prompts for another line. For this table, four field names are identified (in lower case), as well as the data type for each field. Commas separate the commands for each field. The entire SQL command ends with a ;
  55. 55. 55 SQLITE DOT OR SHELL COMMANDS: .TABLES SQLite comes with a handful of ′dot′ commands (aka shell commands) Dot or shell commands allow you to control the SQLite dbms environment (more on these later) Our first dot or shell command: .tables The .tables command identifies the tables within the database. The example includes two tables: ­ course ­ student
  56. 56. 56 INSERTING VALUES INTO TABLES: STUDENT AND INSTRUCTOR The student and course tables do not have any data. To insert data into both student and course tables:
  57. 57. 57 NOTES ON INSERTING Remember that text can be anything. You need to identify the text by enclosing it in single or double quotes. Note: End a SQL command with a semicolon. Any dot commands are NOT SQL commands, so they do not need a semicolon.
  58. 58. 58 SEE WHAT’S IN EACH TABLE: SELECT • Select is a query (question) you ask SQL. • Provide a table name after FROM. • * means ″ALL″ • Two selects (with select *) reveal data in the student and course table
  60. 60. 60 SECOND SHELL COMMAND: .HEADERS ON OR .HEADERS OFF The shell command .headers allows you to turn headers on or off. The headers are the column (or field) names in the table.
  61. 61. 61 INSERTING DATA INTO KNOWN FIELDS In the previous insertion, there were values for each column in the table. What if you don’t have values for each field? (Example: no address for student_id 77) Solution:
  62. 62. 62 OTHER SHELL COMMANDS At the end of the session .quit or .q Help list .help Restarting ­ sqlite3 test.db. << start sqlite and include the college.db name ­ Use .tables to confirm that you have the tables in your database
  63. 63. 63 BACKING UP A DATABASE: .BACKUP AND .RESTORE When in sqlite and your active database, use .backup to create a backup of your database Create a backup, drop the tables from the active database, and restore the database from the backup using .restore
  64. 64. 64 INSTEAD OF A PIPE, USE CSV By default, the pipe is used to separate fields You can use comma-separated values (csv) to separate fields HINT: The csv format is a common Excel format, so data can be input from Excel (as a csv file) into your existing tables.
  66. 66. 66 WAITING FOR MORE INPUT … If you get …> after entering a Sequel command … ­ You did not enter ; ­ The SQLite software is waiting for more input.
  67. 67. 67 WAITING FOR MORE INPUT … Make sure you type a semicolon at the end of each SQL command! The sqlite3 program looks for a semicolon to know when your SQL command is complete. If you omit the semicolon, sqlite3 will give you a continuation prompt and wait for you to enter more text. This feature allows you to enter SQL commands that span multiple lines.
  68. 68. 68 TASK Use .schema to examine how each table was constructed. 1. What are the problems with each table? 2. How are these tables associated (linked)?
  69. 69. 69 RE-EXAMINING THE ERD • What needs to be done with student, course? o Normalize the relationship. o Ensure no repeating groups. o Create an intersection entity (table). o Document items in your data dictionary. o Craft queries to include all elements.
  70. 70. SQLITE PRIMARY KEY SQL and Scripting Training
  71. 71. 71 PRIMARY KEY A primary key is a column or group of columns that identifies the uniqueness of rows in a table. Each table has one, and only one, primary key. SQLite allows you to define primary key in two ways…
  72. 72. 72 PRIMARY KEY: OPTION ONE If the primary key has only one column, use the PRIMARY KEY column constraint to define the primary key as follows: CREATE TABLE table_name( column_1 INTEGER NOT NULL PRIMARY KEY, ... );
  73. 73. 73 PRIMARY KEY: OPTION TWO Second, in case primary key consists of two or more columns, you use the PRIMARY KEY table constraint to define the primary as shown in the following statement. CREATE TABLE table_name( column_1 INTEGER NOT NULL, column_2 INTEGER NOT NULL, ... PRIMARY KEY(column_1,column_2,...) );
  74. 74. 74 PRIMARY KEY–NOT NULL In SQL standard, the primary key column must not contain NULL values. It means that the primary key column has an implicit NOT NULL constraint. However, to make the current version of SQLite compatible with the earlier version, SQLite allows the primary key column to contain NULL values.
  75. 75. 75 PRIMARY KEY EXAMPLE CREATE TABLE course ( course_id INTEGER PRIMARY KEY, course_name TEXT NOT NULL, course_number INTEGER NOT NULL);
  76. 76. 76 PRIMARY KEY EXAMPLE For tables in which the primary keys consist of more than one column, you must use the PRIMARY KEY table constraint to define primary keys. The following slides show how to create the student_course intersection table whose primary key consists of two columns.
  77. 77. RESOLVING M:N RELATIONSHIPS SQL and Scripting Training
  78. 78. 78 RESOLVING M:N RELATIONSHIPS Many-to-many M:N relationships add complexity and confusion to your model and the application development process. To resolve M:N relationships, separate the two entities and create two one-to-many 1:M relationships between them with a third intersection entity. The intersection entity usually contains attributes from both connecting entities.
  79. 79. 79 THE OVERALL MODEL AND SPECIFIC FOCUS Note: The model shows the derivation of composite key on COURSE and STUDENT. For this example, the composite key is collapsed into one field.
  80. 80. 80 START WITH A LOGICAL M:N Student ID Student Name Student Address Course ID Course Description 1111 Priya 123 Hilltop Ave CIS111 Introduction to Computers ENG201 Research Writing MAT211 Calculus I 2222 Tom 234 Carpentaria Way CIS111 Introduction to Computers ENG102 English Composition II MAT101 College Algebra
  81. 81. 81 M:N RESOLUTION AND IMPLEMENTATION INTO SQLITE • Read relationship both ways to ensure that it meets the business rules. • For example: One to Many STUDENTs have One to Many COURSEs, and inversely One to Many COURSEs have One to Many STUDENTs. • The problem is that a M:N cannot be implemented physically. (It makes sense logically!) • Add FK to each entity, which points to back to its associated primary entity. • ″Normalize″ to remove repeating groups. • Add any fields to ensure data is ″atomic.″
  82. 82. 82 M:N RESOLUTION AND IMPLEMENTATION INTO SQLITE • In this version, fields are added to the address to provide more discrete parts of the address (atomic values), which make it easier to maintain. • FK is added in each entity to ″tie together″ each entity pair. • There is still a repeating group of values if a student registers for more than one course. • Note: Document everything you do in the data dictionary.
  83. 83. 83 REPEATING GROUPS OF INFORMATION REMAIN Student ID Student Name Student Address Course ID Course Description 1111 Priya 123 Hilltop Ave CIS111 Introduction to Computers ENG201 Research Writing MAT211 Calculus I 2222 Tom 234 Carpenteria Way CIS111 Introduction to Computers ENG102 English Composition II MAT101 College Algebra
  84. 84. 84 M:N RESOLUTION AND IMPLEMENTATION INTO SQLITE To resolve the M:N relationship, add an intersection entity between STUDENT and COURSE. • The intersect entity between STUDENT and COURSE entities, titled STUDENTCOURSE, contains the PK attributes from STUDENT and COURSE. • The relationship between STUDENT and STUDENTCOURSE is 1:M. • The relationship between COURSE and STUDENTCOURSE is 1:M.
  86. 86. 86 FOREIGN KEYS AND FK CONSTRAINT (ENFORCEMENT) • Keep in mind that FKs are an association from an entity to another PRIMARY entity. • The decomposition of M:N uses FKs to ensure that the data between entities are correctly implemented. • As such, foreign keys must be implemented with constraints. • Constraints enforce that a foreign key in a given entity refers to a PRIMARY entity in an associated entity.
  87. 87. IMPLEMENTING FOREIGN KEYS IN SQLITE SQL and Scripting Training
  88. 88. 88 ENFORCING FOREIGN KEYS SQLite foreign key constraint enforces the relationships between related tables.
  89. 89. 89 SQLITE FOREIGN KEY CONSTRAINT SUPPORT SQLite has supported foreign key constraint since version 3.6.19. To check whether your current version of SQLite supports foreign key constraints, use: PRAGMA foreign_keys; The commands returns 1: enable, 0: disable
  90. 90. 90 SQLITE FOREIGN KEY CONSTRAINT SUPPORT To enable/disable foreign key constraint: PRAGMA foreign_keys = OFF; PRAGMA foreign_keys – ON: Note: Ensure that you have foreign key constraint support turned on.
  91. 91. 91 START WITH TWO TABLES: STUDENT AND STUDENTCOURSE DROP TABLE student; CREATE TABLE student ( student_id text PRIMARY KEY, student_name text NOT NULL, student_address text NOT NULL, student_address_city text NOT NULL, student_address_state_code text NOT NULL, student_address_zip_code text NOT NULL, studentcourse_id text NOT NULL, FOREIGN KEY (studentcourse_id) REFERENCES studentcourse (studentcourse_id) );
  92. 92. 92 CREATE STUDENT DROP TABLE student; CREATE TABLE student ( student_id integer PRIMARY KEY, student_name text NOT NULL, student_address text, course_id text, FOREIGN KEY (course_id) REFERENCES studentcourse (course_id) );
  93. 93. 93 SUMMARY ON PK AND FK Keep in mind that a ″logical″ model that contains M:N relationships will need to be decomposed. Taking a relationship pair that is indicated by M:N will result in 3 entities. The two original entities plus one association (intersection) entity. Note that the association entity now has the many side of the relationship (see diagram). You will work on an exercise that will solidify many SQL concepts including PK/FK and the intersection entity.
  94. 94. 94 REFERENCES (2020). - free flowchart maker and diagrams online. Retrieved November 23, 2020, from SQLite Browser. (2020, November 09). DB Browser for SQLite. Retrieved November 23, 2020, from SQLite. (2020). SQLite Main Website. Retrieved November 23, 2020, from Tutorialspoint. (2020). SQLite Tutorial. Retrieved November 23, 2020, from
  95. 95. 95 INTRODUCTION Ron McFarland Technologist, Educator Source: Microsoft Images
  96. 96. 96 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
  97. 97. 97 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