Lesson 1 Practice — Airport Reader and Runner

In the lesson, you created:

Runner
  ↓
Carrier Reader
  ↓
/DMO/CARRIER

For this assignment, build the same structure for airports:

Runner
  ↓
Airport Reader
  ↓
/DMO/AIRPORT

This assignment does not include the complete solution.

Replace ###

Use your own student/group suffix in all object names.

Objects to create

ZCL_AIRPORT_READER_###
ZCL_SQL_L01_PRACTICE_###

Part 1 — Inspect /DMO/AIRPORT

Open /DMO/AIRPORT with ADT and use Data Preview.

Identify:

airport_id
name
city
country

Record:

Key field:
One existing airport ID:
One existing country:

Use values that actually exist in your system.

Part 2 — Test the query in SQL Console

Open the ADT SQL Console from /DMO/AIRPORT, Data Preview, or your ABAP project.

Write and run a query that returns:

airport_id
name
city
country

Requirements:

• select from /DMO/AIRPORT;
• use an explicit FIELDS list;
• use ORDER BY airport_id;
• verify that the result contains airport records.

The SQL Console query does not need INTO TABLE because SQL Console displays its own result.

Keep the query available. The same selection logic will be placed in the Airport Reader.

Part 3 — Create the Airport Reader

Create:

ZCL_AIRPORT_READER_###

The Reader should be:

PUBLIC
FINAL
CREATE PUBLIC

It should not implement IF_OO_ADT_CLASSRUN.

Why? Because it is not the executable console class.

Part 4 — Define Reader result types

In the public section, define a structure type for one airport containing:

airport_id
name
city
country

Use the corresponding component types from /DMO/AIRPORT.

Then define a standard internal-table type for multiple airports using:

WITH EMPTY KEY

Suggested names:

TY_AIRPORT
TT_AIRPORTS

Part 5 — Implement GET_ALL

Add a Reader method:

GET_ALL

Requirements:

• return your airport table type;
• select from /DMO/AIRPORT;
• use an explicit FIELDS list;
• return airport_id, name, city, and country;
• use ORDER BY airport_id;
• write the SQL result into the returning table.

Do not use SELECT *.

Part 6 — Create the Runner

Create:

ZCL_SQL_L01_PRACTICE_###

This class does implement:

IF_OO_ADT_CLASSRUN

In main:

1. create an Airport Reader object;
2. call GET_ALL;
3. store the returned internal table;
4. display it with out->write( ).

Your structure should be:

Runner
  │
  │ GET_ALL
  ▼
Reader
  │
  │ SELECT
  ▼
/DMO/AIRPORT

Part 7 — Implement GET_BY_COUNTRY

Add:

GET_BY_COUNTRY

Requirements:

• importing country parameter;
• returning airport table;
• WHERE country = @...;
• ORDER BY airport_id.

Call the method from the Runner using the country you recorded in Part 1.

Part 8 — Process returned data

In the Runner, loop over the result of GET_BY_COUNTRY.

Display:

AirportId - City - Name

The Reader reads data. The Runner decides how to display it.

Part 9 — Implement GET_BY_ID

Add:

GET_BY_ID

It should receive:

airport_id

and provide:

airport
found

Requirements:

• importing airport_id;
• exporting airport using your row type;
• exporting found as abap_bool;
• use SELECT SINGLE;
• use the complete key in the WHERE condition;
• check sy-subrc immediately after the SQL;
• set found = abap_true when the row exists.

Part 10 — Call GET_BY_ID

From the Runner:

1. use the valid airport ID you recorded earlier;
2. call GET_BY_ID;
3. display the airport when found = abap_true;
4. otherwise display Airport not found;
5. test a non-existing airport ID too.

Part 11 — Architecture questions

1. What is the difference between running the airport query in SQL Console and putting the query in the Airport Reader? Answer in your own words.

2. Why does the Runner not contain the airport SELECT statements?

3. What is the responsibility of the Reader?

4. What is the responsibility of the Runner?

5. Is ZCL_AIRPORT_READER_### a RAP business service? Explain.

6. Why does ordinary ABAP SQL in this lesson not need a JDBC/ODBC-style connection string?

7. Why does the Reader return typed ABAP data instead of writing directly to the console?

8. Why is WHERE inside GET_BY_COUNTRY preferable to reading every airport and filtering in the Runner?

9. Why is SELECT SINGLE appropriate for GET_BY_ID?

10. Why is sy-subrc checked inside the Reader method rather than in the Runner?

Optional challenge

Add:

GET_BY_CITY

Requirements:

• importing city parameter;
• returning airport table;
• WHERE city = @city;
• ORDER BY airport_id.

Call it from the Runner.

Submission checklist

• You ran the basic /DMO/AIRPORT query successfully in ADT SQL Console.
• ZCL_AIRPORT_READER_### exists in your package.
• ZCL_SQL_L01_PRACTICE_### exists in your package.
• Only the Runner implements IF_OO_ADT_CLASSRUN.
• The Reader defines TY_AIRPORT.
• The Reader defines TT_AIRPORTS.
• GET_ALL contains the SQL for all airports.
• GET_BY_COUNTRY contains the filtered SQL.
• GET_BY_ID contains the SELECT SINGLE.
• The Runner contains no direct SELECT FROM /dmo/airport.
• SQL host variables use @.
• Ordered results use ORDER BY.
• You tested both found and not-found cases.
• You answered the architecture questions.

Useful ADT shortcuts

Action	Shortcut
Open ABAP Development Object	Ctrl + Shift + A
Syntax check	Ctrl + F2
Activate current object	Ctrl + F3
Run console class	F9
Code completion	Ctrl + Space

SQL Console can be opened from the ABAP project, Data Preview, or the table's Open With menu. | Format source | Shift + F1 |