Several Relationships (Cont.) branch-city customer-street account-number branch-name assets balance customer-name customer-cify account- branch account depositor customer branch (a)E-R diagram branch branch-name branch-city assets customer-name customer-street customer-city account-number balance account (b)transformation of E-R diagram Database System Concepts,5th Ed. B.16 @Silberschatz,Korth and Sudarshan
Database System Concepts, 5 B.16 ©Silberschatz, Korth and Sudarshan th Ed. Several Relationships (Cont.)
Several Relationships(Cont.) Corresponding diagrams in the form of rooted trees. branch-name branch-city assets customer-name customer-street customer-city branch customer account-number balance account-number balance account account Database System Concepts,5th Ed. B.17 ©Silberschat乜，Korth and Sudarshan
Database System Concepts, 5 B.17 ©Silberschatz, Korth and Sudarshan th Ed. Several Relationships (Cont.) Corresponding diagrams in the form of rooted trees
Several Relationships(2nd Example) A B A B (a) (b) Diagram(b)contains a cycle. Replicate all three record types,and create two separate diagrams. Database System Concepts,5th Ed. B.18 ©Silberschat乜，Korth and Sudarshan
Database System Concepts, 5 B.18 ©Silberschatz, Korth and Sudarshan th Ed. Several Relationships (2nd Example) Diagram (b) contains a cycle. Replicate all three record types, and create two separate diagrams
Several Relationships (2nd Example) Each diagram is now a rooted tree. A A B C B Database System Concepts,5th Ed. B.19 @Silberschatz,Korth and Sudarshan
Database System Concepts, 5 B.19 ©Silberschatz, Korth and Sudarshan th Ed. Several Relationships (2nd Example) Each diagram is now a rooted tree
Data Retrieval Facility We present querying of hierarchical databases via a simplified version of DL/I,the data-manipulation language of IMS Example schema:customer-account-branch A branch can have several customers,each of which can have several accounts. An account may belong to only one customer,and a customer can belong to only one branch. Database System Concepts,5th Ed. B.20 ©Silberschat乜，Korth and Sudarshan
Database System Concepts, 5 B.20 ©Silberschatz, Korth and Sudarshan th Ed. Data Retrieval Facility We present querying of hierarchical databases via a simplified version of DL/I, the data-manipulation language of IMS. Example schema: customer-account-branch A branch can have several customers, each of which can have several accounts. An account may belong to only one customer, and a customer can belong to only one branch