Quiz 4: Relational Databases and Enterprise Systems
Relational database (RDB) is a group of several sets of data organized by records, columns and tables. It defines a relationship between tables of databases. It uses structured query language. Difference between hierarchial network model and relational data model is given below: The above table explain the difference bewteen hierarchial network and relational data models. Relational data model is the most popular model used today. It requires the users to enter the data only once. It does not require multiple record changes. This minimizes the size of the database. Any details can be easily modified or deleted under this model. All the records or data which is linked to the modified data will also show changes. Thus, the aforementioned points explain the reasons for the popularity of the relational data model. .
Hierarchical data model It is the model that supports the flow of data in a tree structure which means data should flow like a branch of tree, i.e. one-to-many form. It uses defined relationships of parent and child to organize the data. To select the option from the following options which shows how relationships are shown through hierarchal model, all the options are considered as follows: a. In one-to-one form data is flowed from one node to only single other node, data is not flowed in this way in hierarchical data model. Hence this option is not an appropriate option. Hence, Option a is incorrect. c. Many-to-many form of data flow denotes that data flows from many senders to many receivers. It is not followed in the hierarchical data model, this relationship is shown in network data model. Hence, Option c is also incorrect. d. Many-to-one data flow is used where many senders requires to send data only to a single receiver it is not the way in which the data flows in a hierarchical data model. Hence, Option d is also incorrect. b. One-to-many refers to the flow of data from one node to many nodes. This is the same form in which data flows in hierarchical data model, this is like a tree structure. Hence it is correct answer. Hence, Option b is the correct option.
SQL is a programming language which used for retrieving data from master data and by making queries it can used for getting answers after applying calculations in master data and it also used for running reports in application. In the given question the output required from using SQL is accounts having balance below than 50,000. The following output will be received after giving given command in problem: This output shows in whole data only these three accounts having balance lower than 50,000. In getting these outputs SQL uses its retrieval function which helps in retrieving the data having specific attribute.