3. Deleting rows in a table

   1. Syntax

2. Purpose

To remove rows from a table.

3. Prerequisites

For you to delete rows from a table, the table must be in your own schema or you must have DELETE privilege on the table.

The DELETE ANY TABLE system privilege also allows you to delete rows from any table.

4. Keywords and Parameters

   schema	is the schema containing the table. If you omit schema, Oracle assumes the table or view is in your own schema.
   table	is the name of a table from which the rows are to be deleted.
   where_clause	deletes only rows that satisfy the condition. The condition can reference the table and can contain a subquery..   If you omit the where_clause, Oracle deletes all rows of the table or view.
   t_alias	provides a correlation name for the table to be referenced elsewhere in the statement. Table aliases are generally used in DELETE statements with correlated queries.

5. Examples

Basic Examples

The following statement deletes all rows from a table named DEPARTMENT.

DELETE FROM DEPARTMENT;

The following statement deletes from the TEACHER table all professors who have less than 100 Commission:

DELETE FROM TEACHER

WHERE post = 'professor' AND Commission < 100;

3. Lab tasks

   1. Inserting rows in tables

Insert the following rows in tables.

FACULTY	FacNo	Name	Dean	Building	Fund
	1	informatics	Sidorov	5	57398.00
	2	economy	Petrov	3	NULL
	3	linguistics	Popov	4	NULL

DEPARTMENT	DepNo	FacNo	Name	Head	Building	Fund
	1	1	SE	Sidorov	5	14378.00
	2	1	CAD	Perov	5	15000.00
	3	1	DBMS	Ivanov	4	22000.00
	4	2	Accounts	John	3	NULL

TEACHER	TchNo	DepNo	Name	Post	Tel	Hiredate	Salary	Commission
	1	1	Andrew	assistant	2281319	01.02.2001	250	80
	2	1	John	professor	2281550	01.07.2001	400	150
	3	2	Bill	assistant	NULL	17.11.2002	240	80
	4	2	Albert	assistant	NULL	11.11.2001	260	100

SGROUP	GrpNo	DepNo	Course	Num	Quantity	Curator	Rating
	1	1	1	101	33	4	20
	2	1	1	102	35	4	22
	3	3	2	205	20	1	15
	4	3	3	305	25	NULL	40
	5	3	4	405	25	2	37

SUBJECT	SbjNo	Name
	1	pascal
	2	C
	3	OS
	4	inernet
	5	dbms

ROOM	RomNo	Num	Seate	Floor	Building
	1	101	20	1	5
	2	316	150	3	5
	3	201	150	2	2
	4	202	30	2	5

LECTURE	TchNo	GrpNo	SbjNo	RomNo	Type	Day	Week	Lesson
	1	1	1	1	lecture	mon	1	1
	1	2	2	1	lab	mon	1	1
	2	3	3	1	lecture	tue	1	3
	2	4	4	2	practice	wed	1	3
	4	4	5	2	practice	thu	2	4
	4	4	5	3	lab	fri	2	1

Insert in the FACULTY table information about your faculty/ Because of at that time information about teachers dies not exists, use NULL as a value of foreign key that references to the dean of the faculty.

Insert into DEPARTMENT table information about your department and all departments of teachers that teach you. Because of at that time information about teachers dies not exists, use NULL as a value of foreign key that references to the head of the department

Insert into TEACHER table information about all teaches that teach you, including dean of the faculty and head of the departments. . Teacher subordination is set in such a way:

- Dean of the faculty does not subordinate anybody

- Chief of the department subordinates to the dean

- Teachers that has lectures subordinates to the head of the department

- Teachers that has labs subordinates to the teacher that has lectures in the same subject.

Update FACULTY table by changing NULL in DeanFK column to the references to corresponding teacher

Update DEPARTMENT table by changing NULL in HeadFK column to the references to corresponding teacher.

Insert into SGROUP table information about your group.

Insert into SUBJECT table all disciplines that you study.

Insert into ROOM table information about all room where you have lectures.

Insert into LECTURE table information about all lectures that you have.