Writing Basic SQL Queries¶ As part of this section we will primarily focus on writing basic queries. Standard Transformations Overview of Data Model Define Problem Statement – Daily Product Revenue Preparing Tables Selecting or Projecting Data Filtering Data Joining Tables – Inner Joining Tables – Outer Performing Aggregations Sorting Data Solution – Daily Product Revenue …
Exercises – Database Operations¶ Let’s create a table and perform database operations using direct SQL. Exercise 1 – Create Table¶ Create table – courses course_id – sequence generated integer and primary key course_name – which holds alpha numeric or string values up to 60 characters course_author – which holds the name of the author up …
Overview of Transactions¶ Let us go through the details related to Transactions.* We typically perform operations such as COMMIT and ROLLBACK via the applications. COMMIT will persist the changes in the database. ROLLBACK will revert the uncommitted changes in the database. We typically rollback the uncommitted changes in a transaction if there is any exception …
Deleting Data¶ Let us understand how to delete the data from a table. Typical Syntax – DELETE FROM <table> WHERE <condition>. If we do not specify condition, it will delete all the data from the table. It is not recommended to use delete with out where condition to delete all the data (instead we should …
Updating Data¶ Let us see how we can update data in the table. Typical syntax UPDATE <table_name> SET col1 = val1, col2 = val2 WHERE <condition> If WHERE condition is not specified all rows in the table will be updated. For now we will see basic examples for update. One need to have good knowledge …
Inserting Data¶ Let us see how to insert the data into the table. We need to use INSERT clause to insert the data. Here is the sample syntax. INSERT INTO <table_name> (col1, col2, col3) VALUES (val1, val2, val3) If we don’t pass columns after table name then we need to specify values for all the …
