reading-notes

Intro to SQL

Download the free e-book, Learn SQL, which is an excellent introduction to SQL and relational databases.

Practice running common SQL commands using the following SQL Bolt tutorials.

• Lessons 1 through 6 - SQL Queries
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• Lessons 13 through 18 - Database Management
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Summarizing your understanding of relational databases and SQL:

1. What is SQL?

   SQL (Structured Query Language) is a programming language used for managing and manipulating relational databases. It provides a standardized way to interact with databases and perform operations like querying, updating, and managing data.

2. How is it used in software development?

   SQL is commonly used in software development for tasks such as:

   • Retrieving data from databases
   • Storing and retrieving data for applications
   • Implementing data persistence in applications
   • Creating and modifying database schemas
   • Enforcing data integrity and constraints
   • Generating reports and analyzing data

3. Select queries

   Select queries retrieve data from a database table. Example:

   SELECT column1, column2
   FROM table_name;
   

4. Queries with constraints

   Queries with constraints allow you to filter data based on specific conditions. Example:

    SELECT column1, column2
    FROM table_name
    WHERE condition;
   

5. Filtering and sorting query results

   Filtering and sorting query results enable you to refine and order the retrieved data. Example:

    SELECT column1, column2
    FROM table_name
    WHERE condition
    ORDER BY column1 ASC;
   

6. Simple select queries

   Simple select queries retrieve all columns from a table. Example:

    SELECT *
    FROM table_name;
   

7. Multi-table queries with JOINs

   Multi-table queries with JOINs combine data from multiple tables using common columns. Example:

    SELECT column1, column2
    FROM table1
    JOIN table2 ON table1.column = table2.column;
   

8. Inserting rows

   Inserting rows allows you to add new records to a table. Example:

    INSERT INTO table_name (column1, column2)
    VALUES (value1, value2);
   

9. Updating rows

   Updating rows modifies existing records in a table. Example:

    UPDATE table_name
    SET column1 = value1
    WHERE condition;
   

10. Deleting rows

    Deleting rows removes specific records from a table. Example:

    DELETE FROM table_name
    WHERE condition;
    

11. Creating tables

    Creating tables defines a new table in the database. Example:

    CREATE TABLE table_name (
        column1 datatype,
        column2 datatype,
        ...
    );
    

12. Altering tables

    Altering tables allows you to modify the structure of an existing table. Example:

    ALTER TABLE table_name
    ADD column_name datatype;
    

13. Dropping tables

    Dropping tables deletes a table from the database. Example:

    DROP TABLE table_name;
    

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