Appendix D Network Model Hayes Main Harrison A-102400 Lindsay Park Pittsfield A-222700 Turner Putnam Stamford A-305 350 Figure D.5 Sample database corresponding to diagram of Figure D.3b If a relationship includes descriptive attributes,the transformation from an E-R diagram to a data-structure diagram is more complicated.A link cannot contain any data value,so a new record type needs to be created and links need to be established. Consider the E-R diagram of Figure D.2a.Suppose that we add the attribute access date to the relationship depositor,to denote the most recent time that a customer accessed the account.This newly derived E-R diagram appears in Fig- ure D.6a.To transform this diagram to a data-structure diagram,we must 1.Replace entities customer and account with record types customer and account, respectively. 2.Create a new record type access date with a single field to represent the date. 3.Create the following many-to-one links: access_date customer account cusfonter_name depositor account number customer_street balance customer city (a)E-R diagram customer_name customer_sfreet customer_cify account number balance customer account customer_date account date access date access date (b)Network diagram Figure D.6 E-R diagram and its corresponding network diagram.4 Appendix D Network Model Figure D.5 Sample database corresponding to diagram of Figure D.3b. If a relationship includes descriptive attributes, the transformation from an E-R diagram to a data-structure diagram is more complicated. A link cannot contain any data value, so a new record type needs to be created and links need to be established. Consider the E-R diagram of Figure D.2a. Suppose that we add the attribute access date to the relationship depositor, to denote the most recent time that a customer accessed the account. This newly derived E-R diagram appears in Fig￾ure D.6a. To transform this diagram to a data-structure diagram, we must 1. Replace entities customer and account with record types customer and account, respectively. 2. Create a new record type access date with a single field to represent the date. 3. Create the following many-to-one links: Figure D.6 E-R diagram and its corresponding network diagram