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This is a hands-on technical course session focused on configuring Oracle SQL Developer, establishing database connections, and modifying table structures using SQL commands. The instructor guides participants through troubleshooting connection issues, editing configuration files (e.g., listener.ora), restarting services, and altering the employees table by adding first_name and salary columns. The session emphasizes practical execution, real-time debugging, and use of SQL*Plus and SQL Developer interfaces.

Topic (Timeline)

1. SQL Developer Setup and Connection Troubleshooting [00:00:00 - 00:01:56]

Instructor guides participants to open SQL Developer and navigate to the “Local” connection folder.
Participant (Sir Ray) encounters connection failure due to incorrect hostname in configuration.
Instructor directs Sir Ray to open command prompt/terminal and run hostname to verify system hostname.
Participant is instructed to edit the listener.ora file (line 19) to match the correct hostname (ray-f3lz).
Participants are advised to reference Google Docs for correct configuration values.
Instructor confirms file edits and instructs restart of computer to apply changes.

2. Database Debugging and Table Inspection Using SQL*Plus [00:01:56 - 00:03:17]

Instructor shifts focus to debugging using SQL*Plus to inspect the employees table.
Participants attempt to query the table and receive an error indicating missing first_name column.
Instructor demonstrates use of DESCRIBE employees to inspect table structure.
Confirms that employees table lacks first_name and salary columns.
Instructor advises removing prior test code to avoid interference and prepares for table modification.

3. Altering the Employees Table: Adding Columns [00:03:17 - 00:05:03]

Instructor demonstrates filtering tables in SQL Developer by typing “employees” in the filter box for quick access.
Introduces SQL ALTER TABLE syntax to add two new columns: first_name (VARCHAR) and salary (DECIMAL).
Code example is provided via Google Docs; participants instructed to execute in SQL Developer or terminal.
Multiple participants (Sir Joseph, Sir Miguel) attempt the command but encounter syntax errors.
Instructor identifies common error: incorrect column name (first employees instead of first_name) and misplaced commas.

4. Correcting Syntax and Verifying Table Alteration [00:05:03 - 00:06:19]

Instructor corrects syntax: instructs Sir Jerry to place ADD on a new line and remove trailing comma.
Participants re-run: ALTER TABLE employees ADD first_name VARCHAR2(50), ADD salary DECIMAL;
Confirmed successful execution via DESCRIBE employees — now shows first_name and salary columns.
Instructor emphasizes need to select/refresh view to see updated structure.
Participants are instructed to remove prior test code to prepare for next step (SELECT queries).

5. System Restart and Final Validation [00:06:19 - 00:06:53]

Instructor notes that Sir Ray and Mame Christine are restarting their systems to ensure configuration persistence.
Instructor checks Sir Joseph’s screen to confirm successful table alteration.
Final check: participants confirm no errors after restart and refresh.
Session ends with instructor preparing to proceed to next step (SELECT queries), though not fully executed in transcript.

Appendix

Key SQL Commands

DESCRIBE employees — inspect table structure
ALTER TABLE employees ADD first_name VARCHAR2(50), ADD salary DECIMAL; — add columns (correct syntax)
hostname — verify system hostname for connection configuration

Tools Used

Oracle SQL Developer
SQL*Plus
Command Prompt / Terminal
Text editor (e.g., Code) for editing listener.ora

Common Pitfalls

Incorrect hostname in listener.ora → connection failure
Syntax errors in ALTER TABLE: using first employees instead of first_name, or trailing commas
Not restarting system after config changes → changes not applied
Not refreshing table list in SQL Developer after alteration → column not visible

Action Items for Learners

Verify hostname matches listener.ora configuration
Always use DESCRIBE to confirm table structure after DDL changes
Restart services or system after modifying Oracle network config files
Use Google Docs as reference for correct SQL syntax and file paths

ORACLE PL/SQL Fundamentals - rey-njhi-20241210-131824

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Summary

Overview