Introduction

Lessons in this tutorial

• Lesson 1: Set up the database connection
  
  The first step in accessing the database is to set up the connection. From that connection, EGL will create a starting set of data parts and logic parts, and you will write a simple data access program to test the connection.
• Lesson 2: Basic SQL operations in EGL
  
  If you went through the tutorial Introducing EGL (a quick-start guide), you learned about the EGL parts necessary to access a relational database and the commands with which you can read and write data in a database. This lesson covers these concepts in more detail.
• Lesson 3: Managing a cursor with open and forEach
  
  Cursors are SQL constructs that behave like a bookmark, pointing to a row and allowing you to step through a series of search results (that is, table rows) one at a time. EGL can manage cursors for you, but it also provides the open and forEach statements to take advantage of cursors.
• Lesson 4: Constructing queries dynamically with prepare
  
  The EGL prepare statement lets you construct SQL statements dynamically.
• Lesson 5: Retrieving more complex data with table joins
  
  Up to this point, each data access function has retrieved rows from only one table. In this lesson, you learn to use SQL table joins with EGL to work with multiple tables at once.
• Lesson 6: Executing arbitrary SQL code
  
  In this lesson, you learn more flexible ways of working with SQL code in EGL.
• Lesson 7: Exception handling and rollbacks
  
  It's especially important to properly handle errors in applications that access data sources in order to avoid retrieving incorrect data, inserting incorrect data, or otherwise creating inconsistencies between the application and the data source. In this lesson, you will learn about a few tools that you can use to respond to errors when accessing relational databases.
• Troubleshooting
  
  This section lists possible problems in working with the tutorial application. If you are not getting the results that you expect, here are some things you can try to fix the problem.
• Completed CRUDTest.egl file after lesson 2
  
  This code is the completed version of the CRUDTest.egl file. If you see any errors marked by red X symbols in the file, make sure your code matches this code:
• Completed selectItems.egl file after lesson 3
  
  This code is the completed version of the selectItems.egl file after lesson 3. If you see any errors marked by red X symbols in the file, make sure your code matches this code:
• Completed selectItems.egl file after lesson 4A
  
  This code is the completed version of the selectItems.egl file after lesson 4A. If you see any errors marked by red X symbols in the file, make sure your code matches this code:
• Completed selectItems.egl file after lesson 4B
  
  This code is the completed version of the selectItems.egl file after lesson 4B. If you see any errors marked by red X symbols in the file, make sure your code matches this code:
• Completed printCustomerOrders.egl and records.egl files after lesson 5
  
  This code is the completed version of the printCustomerOrders.egl and records.egl files after lesson 5. If you see any errors marked by red X symbols in either file, make sure your code matches this code:
• Completed CustomerTableOperations.egl and duplicateTable.egl files after lesson 6
  
  This code is the completed version of the CustomerTableOperations.egl and duplicateTable.egl files after lesson 6. If you see any errors marked by red X symbols in either file, make sure your code matches this code:
• Completed exceptionHandlingTest.egl file after lesson 7
  
  This code is the completed version of the exceptionHandlingTest.egl file after lesson 7. If you see any errors marked by red X symbols in the file, make sure your code matches this code: