Imagine your Oracle database like a school, and you’re Teacher decides to remove a student (row) from the classroom(table).

Let’s see how the journey works step by step:

1)Classroom = Oracle Table

2)Students = Rows (Records)

3)Class Teacher = Oracle Server Process

4)Attendance Register = Data Dictionary

User fires DELETE statement:

DELETE FROM students WHERE grade = 'D';

Internal Processing Steps:

Client Process Sends DELETE Statement to Server Process
The teacher receives a request to remove a student from the classroom.

Syntax Check (Parsing)
The teacher checks if the request is grammatically correct — proper command, keywords, and a semicolon.

Semantic Check
Teacher verifies if the classroom exists and whether the condition (like grade = 'D') makes sense.

Object Resolution
Teacher confirms that the ‘students’ classroom (table) exists in the school records (data dictionary).

Optimization
Decides the fastest way to find those students — by roll number, grade, or alphabetical order.

Row Source Generation
Finds the exact students matching grade = 'D' to be removed.

Server Process Accesses the Data Block
The teacher goes to the attendance sheet (data block) and locates the students.

Undo Data (Before Image) Created
Teacher writes the removed student's name on a temporary sticky note — in case Principal says "wait, don’t remove".

Rows Marked as Deleted in Data Block
Crosses the student’s name in the attendance sheet (not physically removed yet).

Redo Log Entry Generated
The school office makes a note in their official register about this action.

Waits for COMMIT / ROLLBACK
If the Principal signs the removal order (COMMIT), students officially leave. If not (ROLLBACK), they stay.

After COMMIT — Rows Permanently Removed from Table
Once signed, students’ names are erased from the attendance sheet permanently.


Flow chart:



Simple Analogy:

DELETE → Teacher goes through the attendance sheet, crosses names one by one, keeps a sticky note for each, and waits for the Principal’s approval to finalize.

TRUNCATE → Principal enters the classroom and tells everyone to leave immediately, locks the classroom, and clears the attendance register without sticky notes.

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