CA Endevor/DB™ for CA IDMS™ (CA Endevor/DB) Example. The example below defines a basic database name table that is suitable if all. Using the IDMS Database Automatic System Facility (ASF) · Using Common Facilities · Command Facility Basics of Using TCF. Last update July 29, + Idms (integrated Database Management System) Interview Questions and Answers, Question1: What does a store statement do? Question2: What is.
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This is free Mainframe tutorials. I will keep updating and adding more contents as and when possible. Table of Contents 1. Application Development Bwsics 1. Different Database Architectures 1. Logical Database Structure 2. Entity, Logical and Physical Structure 2. Attributes, Relationships — Training Database 2. Executable and Compiler Directive 3.
Virtual Storage Layout 3. DML Databass Steps 4. Physical Database Structure 4. Record occurrence — Prefix, Data 5. Bachman Diagram For Record Type 6. Bachman Diagram For Set 7. Access By Walking Sets i.
Access Through Set Relationship 7. Retrieval By Sort-Key Value 7. Generic Key Retrieval 7. Retrieval Using Indexed Set 7. Retrieval By Sweeping Areas 8.
Find and Get 8. Types of Set Relationships 9. Multiple Set Membership 9. Nested Structure — Bill Of Material Set Membership Options Bachman Diagram and Examples Recovery and Restart Journal Files, Checkpoints Recovering From Failures Area Usage Modes Record Locks — Implicit, Explicit Employee Database Appendix B: A DBMS is a software subsystem that manages a collection basisc interrelated data elements, stored in a database, that can be accessed in a shared manner by a collection of application programs.
Database Approach There are many advantages to maintaining all an organization data in a central pool or reservoir, so that it can be shared by a number of application programs. We can place the advantages of the database approach dztabase two categories: Data integrity and Application development productivity.
Each piece of information is stored only once in the central pool and application programs access it via the database management system. Multiple copies of same data do not exist in different stages of updating. Application Development Productivity Simplified Programming: This results in application programs that are less complex than those that work with conventional files.
If a record format changes, all programs that access the record must also be modified.
With a DBMS, since programs do not access data directly, changes can be made to the structure of the database without requiring that applications programs be modified.
Data and programs are independent. These two things increase programmer productivity. Supplier l l Order l l Line Item 1. The term network in this context has nothing to do with a communications network! It refers rather to the kinds of data structures and operators e. Supplier Part l l l l l l l l l Order l l l l l l l l l l l l Line Item l l l l l l l Quotation l Dependent records Line-Item and Quotation have dataabse than one parent.
Relational In a relational DBMS, data is represented in the form of tables in which all associations are expressed using values in the stored data and no embedded pointers are required to represent relationships between records. In the relational model, the data and the relationships among data are represented by a collection of datxbase.
The network model differs from the relational model in that data are represented by collection of records, and relationships among data are represented by links.
Relational model supports one-to-many and many-to-many links. But, Network model supports only one-to-many links and it does not support many-to-many links. Links are implemented in the Network model by adding pointer fields to records that are associated via a link.
To illustrate the implementation of the Network model, suppose the Dept-Employee relationship is one-to-many from Dept to Employee. An Employee record occurrence can be associated with basiccs one Dept record occurrence.
IBM MAINFRAME: Need info about the basics of IDMS Database
Thus, we need only one pointer in the Employee record occurrence to represent the Dept-Employee relationship. However, a Dept record occurrence can be associated with many Employee record occurrences. Rather than using multiple pointers in Dept record, we can use a ring structure or chain pointers to represent all employees in the given department. Chain pointers form a circular list.
Consider another example given below about chain pointers. In the Training department, many courses are conducted for different subjects. There are two record types, namely Subject and Course, which are linked. C and so on. It is clear from the preceding discussion that the Network model is closely tied to the implementation. Querying is simple in the relational model, while it is significantly more complicated in the network model.
The programmer is forced to think in term of links, and how to traverse them to get at needed information. Data manipulation in the network model is hence said to be navigational. Network structured databases can be used to handle high volume transaction processing applications which have demanding performance requirements. Relational databases can be used to accommodate user-generated applications. Combining both network and relational capabilities in one system provides the installation with a versatile tool for meeting both production requirements and the ease-of-use requirements of end users.
This means that data stored in the form of network structures can be accessed by conventional application programs, but can also be accessed by the relational facilities for those applications that require a relational view of the network structured data. In turn, data entered through the relational facility can be used to update the production, network-structured database.
The heart of any database product is the software component that manages access to the database. This component is most commonly called the DBMS. A major purpose of a DBMS is to isolate application programs from the details concerning how data elements are physically stored. The DDL is used by database designers to describe the logical and physical structure of the database to DBMS software and to application programs. Application programs use DML to specify how the database is accessed.
Application programs make requests for access to the database by executing DML statements; the DBMS intercepts these requests and performs the required accesses to the database to satisfy these requests.
ASF is menu oriented and relatively easy to use. At the highest level is the application environment, where we discuss the nature of the entities that we are representing in the database.
Entities consist of those objects, people, or ideas about which we are storing data. On a lower level we are concerned with software, where we describe the logical structure of the database that we are using to represent information about entities in the database. On a still lower level is the hardware, where we describe the physical structure of the database and the way in which logical records are implemented in computer storage. Attributes, Relationships — Training Database We will be using a hypothetical Training Department database that might be used to maintain information about courses conducted and faculties.
Please consider the following scenario for the Training Department. At any given point of time, multiple courses can be in progress. A faculty can teach multiple subjects. A subject can be taught by multiple faculties. The database will store information about the following entities. An attribute is a particular piece of information that is associated with an entity. We can identify a number of relationships between the entities about which we are storing information.
Each course is conducted by one faculty, but each faculty conducts many courses. The Course and Participant entities form another one-to-many relationship. Each participant attends one course, and each course has many participants. The Participant and Performance entities also form one-to-many relationship. The Faculty and Subject entities form a many-with-many relationship. One faculty can teach many subjects, and a subject can be taught by many faculties.