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Integrity Constraints
- 1. Integrity constraints Presented by MadhavBansal Roll no. - 1336710027 Presented by Varsha Divakar Roll no.- 1336710026
- 2. Data base managementsystem DBMS is a collection of interrelated data and a set of program to Access those data. Management of data involve both defining structure for storage of information & providing mechanism for manipulation of information. Data base system ensure the safety of information stored ,despite system or an unauthorized access in attempted on data base.
- 3. . Integrity meanssomething like 'be right' and consistent. The data in a database must be right and in good condition.
- 4. Need of integrityconstraint Many user enter data item in data base becomes very important that the data item &association among them destroy . Therefore Data insertion ,updating& other processes have to be perform in such a way that data integrity is not affected . For this integrity checks are made at data level by checking the value to certain specify rule.
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- 7. Domain integritymeans the definition of a valid set of values for an attribute. You define - data type, - length or size - is null value allowed - is the value unique or not for an attribute. The range (values in between) and/or specific values for the attribute. Some DBMS allow you to define the output format and/or input mask for the attributes.
- 8. Emp_ID ADD PhoneNo. Age Name X1 VBN 111 21 A X2 MTR 123 23 E X3 MUB 432 22 D (Age>=18) Varchar Integer Character
- 9. The entityintegrity constraint states that primary keys can't be null. On the other hand, there can be null values other than primary key fields. Null value is different from zero value or space. The entity integrity constraints assure that a specific row in a table can be identified.
- 10. REG.NO MODEL_id RATE ABC-1121 45,00$ ACC-223 6 65,00$ BAA-441 2 57,00$ NULL 5 35,00$ CCE-325 3 45,00$ CCE-326 4 61,00$ Null value not allowed
- 11. The referential integrityconstraint is specified between two tables and it is used to maintain the consistency among rows between the two tables. The rules are: 1. You can't delete a record from a primary table if matching records exist in a related table. 2. You can't change a primary key value in the primary table if that record has related records. 3. You can't enter a value in the foreign key field of the related table that doesn't exist in the primary key of the primary table. 4. However, you can enter a Null value in the foreign key, specifying that the records are unrelated.
- 12. Primary table Related table Model_idMark Model 1. ford focus 2. ford mondeo 3. Peugeot 307 4. Peugeot 407 REG.NO MODEL_id RATE ABC-112 1 45,00$ ACC-223 6 65,00$ BAA-441 2 57,00$ BSA-224 5 35,00$ CCE-325 3 45,00$ CCE-326 4 61,00$ Example of referential
- 13. S.No Emp_ID ADD 1X1 VBN 2 X2 MTR 3 X2 JHS 3 X2 JHS Same tuple doesn’t allow
- 14. S.No. Emp_ID ADD 1X1 VBN 2 X2 MTR 3 x3 JHS 3 X4 KNP
- 15. Foreign Key IntegrityConstraint There are two type foreign key integrity constraints: • cascade update related fields • cascade delete related rows. These constraints affect the referential integrity constraint.
- 16. I. CascadeUpdate RelatedFields Anytime you change the primary key of a row in the primary table, the foreign key values are updated in the matching rows in the related table. This constraint overrules rule 2 in the referential integrity constraints.
- 17. Primary table REG.NO Model_i d MarkModel ABC-112 1. ford focus ACC-223 2. ford mondeo BAA-441 3. Peugeot 307 BSA-224 4. Peugeot 407 REG.NO MODEL_i d RATE ABC-112 1 45,00$ ACC-223 2 65,00$ BAA-441 3 57,00$ BSA-224 4 35,00$ CCE-325 5 45,00$ CCE-326 6 61,00$ Related table 7. 7. Example of Cascade Update Related Fields
- 18. II. CascadeDelete RelatedRows Any time you delete a row in the primary table, the matching rows are automatically deleted in the related table. This constraint overrules rule 1 in the referential integrity
- 19. Primary table REG.NO Model_i d MarkModel ABC-112 1. ford focus ACC-223 2. ford mondeo BAA-441 3. Peugeot 307 BSA-224 4. Peugeot 407 REG.NO MODEL_i d RATE ABC-112 1 45,00$ ACC-223 2 65,00$ BAA-441 3 57,00$ BSA-224 4 35,00$ CCE-325 5 45,00$ CCE-326 6 61,00$ Related table Example of Cascade Delete Related Rows
- 20. S.No. Name Agecourse Ph No. Roll no. Enroll no. 1 Amit 21 B.Tech 542312 432876 234567 2 Anju 20 B.Tech 543122 432873 234890 3 Vijay 18 MBA 543114 432098 456789 4 Tarun 20 B.Tech 765432 432876 456789 5 Sita 19 BBA 987654 432098 987543 6 Rita 19 BCA 123456 432878 123456 7 Dinesh 20 B.Tech 765434 NUL3 456789 7. Dinesh 20 B.tech. 765434 547894 456789 547894 567483 (Age => 18) Domain Constraint