Baze Podataka Ispit

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In every SELECT query, the SELECT and FROM clauses are mandatory. The SELECT clause specifies the columns that should be included in the result set, while the FROM clause specifies the table or tables from which the data should be retrieved. Therefore, both SELECT and FROM are necessary components of a valid SELECT query. The other options listed (GROUP BY, WHERE, and ORDER BY) are optional clauses that can be included depending on the specific requirements of the query.

The correct answer includes the functions SUM, AVG, MIN, MAX, and COUNT. These functions are commonly used in SQL queries to perform calculations and retrieve specific information from a database. The SUM function calculates the total sum of a column, the AVG function calculates the average value, the MIN function retrieves the minimum value, the MAX function retrieves the maximum value, and the COUNT function counts the number of rows that meet certain criteria. These functions are essential in data analysis and reporting tasks in SQL.

Durability is a characteristic of a transaction that states that once the transaction is completed (confirmed changes), its effects cannot be lost. This means that any changes made by the transaction will persist even in the event of system failures or crashes. The durability property ensures that the changes are permanently stored and can be recovered, providing reliability and data integrity.

The correct answer is "CREATE" because in SQL, the CREATE statement is used to define or create database objects such as tables, views, indexes, and procedures. It is a Data Definition Language (DDL) command that allows users to create new database objects in the database schema. The CREATE statement is essential for setting up the structure and layout of the database before any data can be inserted, selected, updated, or deleted.

When one transaction sets a shared lock (SL) on a resource, it means that other transactions can also set shared locks on the same resource. This allows multiple transactions to read the resource simultaneously without conflicting with each other. Therefore, the second transaction is able to set a shared lock (SL) on the resource.

The given correct answer states that the column is a foreign key in relation to the table ImeTabele. This means that the column in question is used to establish a relationship with another table by referencing its primary key.

The correct answer is that an index can be removed at any time and regardless of the content of its table. This means that the index can be dropped even if the table is not empty or if there are still columns indexed by it. There is no requirement to remove the table before removing the index.

The correct answer is "ALTER". ALTER is the SQL command used to modify the structure or definition of an existing table. It allows you to add, modify, or delete columns, constraints, and other attributes of a table. With the ALTER command, you can also rename a table or change its data type. This command is essential for making changes to an existing table without having to recreate it from scratch.

The correct answer is "Prom1 >= Prom2 AND Prom1". This is because the expression "Prom1 BETWEEN Prom2 AND Prom3" checks if the value of Prom1 is between the values of Prom2 and Prom3, inclusive. In the given answer, "Prom1 >= Prom2" checks if Prom1 is greater than or equal to Prom2, and "Prom1" ensures that Prom1 is not greater than Prom2. Therefore, this expression is equivalent to "Prom1 BETWEEN Prom2 AND Prom3".

The correct answer is "Pristup podacima iz prezentacionog sloja." This means that the type of data access used in Access applications is from the presentation layer. In other words, data is accessed from the user interface or front-end of the application. This could involve retrieving, displaying, and manipulating data that is presented to the user.

After performing the projection operation, the number of tuples in the resulting relation can either be the same or smaller than the number of tuples in the original relation. This is because the projection operation removes duplicate tuples from the original relation. Therefore, if there are duplicates in the original relation, the resulting relation will have fewer tuples. If there are no duplicates, the number of tuples will remain the same.

DB brokeri su klase posrednici preko kojih se razmenjuju podaci između aplikacije i SUBP. Ovo znači da ove klase omogućavaju komunikaciju između aplikacije i sistema za upravljanje bazama podataka, omogućavajući aplikaciji da pristupa, čita i menja podatke u bazi podataka. Ova komunikacija se obično odvija putem odgovarajućih SQL naredbi koje se izvršavaju preko DB brokera.

After performing the projection operation, the number of attributes in the resulting relation will be equal to or smaller than the number of attributes in the original relation. This is because the projection operation eliminates duplicate tuples and selects only the specified attributes, which may result in a reduction in the number of attributes.

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The correct answer is Access and MS Jet DB engine. These are both examples of integrated development environments (IDEs) commonly used for database management. Access is a Microsoft product that provides a user-friendly interface for creating and managing databases, while MS Jet DB engine is the underlying technology that powers Access and allows for efficient storage and retrieval of data. Together, Access and MS Jet DB engine form a comprehensive solution for database development and management.

The correct answer states that there are tags within standard HTML tags that can contain programming code, including SQL commands. This suggests that accessing a database directly from an ASP or JSP page can be done by embedding SQL commands within these specific tags.

JSTL stands for JSP Standard Tag Library, which is a library of tags used in JSP pages. These tags provide a convenient way to perform common tasks, such as looping through a collection, formatting data, and manipulating strings. By using JSTL, developers can simplify their JSP code and make it more readable and maintainable.

The correct answer states that the difference operation in relational algebra forms a new relation by including all tuples from the first relation that are not present in the second relation. This means that the resulting relation will only contain the tuples that are unique to the first relation and do not appear in the second relation.

Normalization of a relational schema involves decomposing a poorly structured schema into two or more schemas that comply with the desired "normal form". This process helps eliminate redundancy, improve data integrity, and ensure efficient data management. By breaking down the schema into smaller, more organized parts, it becomes easier to maintain and update the database.

The correct answer states that it is not possible to enter a value for one attribute without also entering a value for at least one other attribute. This means that when entering data, all relevant attributes must be filled in, and leaving any attribute blank is not allowed.

The correct answer is "Njegovo izvršavanje ne zavisi od izvršavanja spoljnog upita; Izvršava se na početku." This means that the execution of the subquery is independent of the execution of the outer query and it is executed at the beginning.

The correct answer states that a relation is in BCNF if it is in the third normal form and any additional transitive dependencies between non-key attributes are eliminated. This means that the relation has been properly normalized and all non-key attributes are functionally dependent on the key attributes. By eliminating transitive dependencies, the relation avoids redundancy and ensures data integrity.

The correct answer states that consistency is the property of a transaction that states that it should transform the database from one consistent state to another. This means that the transaction should ensure that the changes made to the database maintain its integrity and adhere to any constraints or rules defined for the database. In other words, the transaction should not leave the database in an inconsistent or invalid state after it is executed.

In case of a computer system failure where transactions are being processed, the correct answer suggests that the correct state of the database can be reconstructed based on the last correct backup copy of the database and by repeating the transactions that occurred after the backup was made. This approach ensures that the database is restored to a consistent and accurate state by using the most recent backup and replaying the transactions that were made since then.

Relational algebra is a set of operators used to work with relations, and the results of these operations are also relations.

After the selection operation, the number of tuples in the resulting relation can be equal to or less than the number of tuples in the original relation. This is because the selection operation filters out certain tuples based on a specified condition, so it is possible that some tuples are removed from the original relation, resulting in a smaller number of tuples in the resulting relation.

By removing the value of one attribute, it is possible to remove the values for unwanted attributes.

The correct answer means that "opšte pravo" includes all the specific rights assigned to tables, as well as the ability to create views on those tables and the rights to create basic tables.

The correct answer is "neograničena prava nad BP, koja ima korisnik koji je administrator BP." This means that DBA Opšte pravo refers to unlimited rights over the database, which are held by a user who is the administrator of the database. This option states that the user has unrestricted privileges and control over the entire database.

The correct answer is "kriterijuma za valjanost (kvalitet) šeme relacije" because normalna forma refers to the criteria for the validity (quality) of a relation schema. It is a set of rules that determine the structure and organization of the data in a relational database. The normal form ensures that the data is organized efficiently, eliminates redundancy and anomalies, and allows for easier data manipulation and retrieval.

The explanation for the given correct answer is that in order for a relation to be in 1NF (First Normal Form), each attribute must have a scalar type, meaning that the value of each attribute is single-valued and indivisible. This means that each attribute should only contain a single value and cannot be further divided into smaller components. This ensures that the relation does not have any repeating groups or multi-valued attributes, which is a violation of 1NF.

A Recordset (CRecordset) in C++ or a ResultSet in Java is a DB broker class that accepts a set of records obtained from an SQL query on a database.

In object-oriented programming, application development involves building objects that are grouped based on their functionality. These groups are also referred to as layers. This approach allows for better organization and separation of concerns within the application. Each layer can have its own set of objects and responsibilities, making the application more modular and easier to maintain.

The correct answer is that the possible consequences of redundancy in a relationship are multiple insertions, multiple changes, and multiple deletions. This means that when redundancy occurs, there can be duplicate entries, repeated modifications, and multiple deletions of the same data.

If the transaction is interrupted during the execution of the COMMIT command, the values of the after-image can be read from the log file and the database can be brought to a consistent state. This means that any changes that were made to the database before the interruption can be applied, ensuring that the database remains consistent. Therefore, it is possible to recover the transaction and bring the database back to a consistent state.

A relation has a good structure when there are no drawbacks or issues that can be observed through queries and the relational database structure itself. In other words, it means that the relation is well-designed and efficient, and there are no apparent problems or limitations when working with it. This suggests that the relation is optimized and can be easily queried and manipulated without any noticeable drawbacks.

The correct answer is the repetition of "Anomalija unošenja". This suggests that the given set of anomalies includes the same anomaly multiple times.

The basic application model in object-oriented programming consists of the presentation layer, business logic layer, and data layer. The presentation layer is responsible for the user interface and displaying information to the user. The business logic layer contains the code that implements the application's rules and processes. The data layer is responsible for storing and retrieving data from a database or other data source. These three layers work together to create a functional and efficient application.

The correct answer states that the operation of Presek in relational algebra forms a new relation by combining two input relations and including only the tuples from the first relation that are also present in the second relation. This means that the resulting relation will contain only the tuples that have a matching value in both relations.

The correct answer is that the union operation in relational algebra forms a new relation that contains all tuples from both input relations. This means that the resulting relation will include all tuples from both input relations without any duplicates.

The correct answer is the list of functions that ensure access control. These functions include creating and removing user accounts, assigning and removing general privileges for working with a database, assigning and removing specific privileges, creating database tables, and deleting desired records from the tables. These functions collectively help in controlling access to the system and its resources.

The correct answer is "postoji deo (podskup) atributa koji na isti način određuje drugi atribut". This means that there is a subset of attributes that determine another attribute in the same way. This is a characteristic of a partial functional dependency, where a part of the attributes can determine another attribute, but not all of them.

When dealing with nested transactions, a COMMIT is required at all transaction levels, up to the deepest nested level. This means that each nested transaction must be committed individually before the changes are accepted.

The three basic ways of accessing a database from applications are through the presentation layer, the business logic layer, and the data layer. The presentation layer is responsible for displaying information to the user and receiving user input. The business logic layer handles the processing and manipulation of data according to the business rules and logic. The data layer is responsible for storing and retrieving data from the database. These three layers work together to provide a seamless interaction between the application and the database.

This answer suggests that "pristup podacima iz prezentacionog sloja" refers to when the functions for reading, updating, and adding data from/to the database are defined directly in the user interface code. This means that the data access is controlled by the user and provides privacy to the user. It implies that the user interface code handles the data operations without involving any separate data access layer.

The correct answer is "ne postoji ni jedan deo (podskup) atributa koji na isti način određuje drugi atribut" which translates to "there is no subset of attributes that determines another attribute in the same way." This means that in a total (complete) functional dependency, there are no redundant or unnecessary attributes that can determine another attribute. Every attribute is uniquely determining the other attribute.

The correct answer states that in a relation to be in 2NF, all attributes of the entity that are not primary keys must depend on the entire primary key. This means that the values of these attributes are determined solely by the primary key and not by any other non-key attributes. This ensures that there are no partial dependencies in the relation, where an attribute depends on only a part of the primary key.

The given answer states that a relation is in 3NF if there is no functional dependency where a non-key attribute transitively depends on any candidate key. This means that all non-key attributes should depend only on the candidate keys and not on other non-key attributes. This condition ensures that there are no unnecessary dependencies between non-key attributes, leading to a more efficient and well-structured database design.

The correct answer is "Otkaz sistema u toku izvršenja programa" and "Više korisnika pristupa istim podacima (čitanje i izmena)". These options highlight the potential dangers that can occur during transaction execution. System failure during program execution can lead to data loss or corruption. Additionally, when multiple users access the same data for reading and modification simultaneously, it can result in data inconsistency or conflicts. These risks need to be identified and addressed to ensure the integrity and reliability of transactions.

The correct answer is "nasilno ostvarivanje serijabilnosti kod konkurentnog izvršavanja transakcija" which means "forceful enforcement of serializability in concurrent transaction execution". This refers to the mechanism of ensuring that concurrent transactions are executed in a way that maintains the illusion of serial execution, even though they may be executed concurrently. This mechanism involves techniques such as locking and conflict resolution to prevent conflicts and ensure the consistency of the database.

The correct answer includes the basic elements of the client-server paradigm. These elements are:
1. Uspostava konekcije po zahetvu klijenta (Establishing a connection upon client's request)
2. Klijent šalje zahtev za servisom (Client sends a request for a service)
3. Server pruža usluge (servise) iskljucivo po zahtevu klijenta (Server provides services exclusively upon client's request)
4. Raskid konekcije vrsi klijent (Client terminates the connection)

These elements represent the fundamental interactions between the client and server in a client-server architecture.

The correct answer is "ne mogu se pojaviti novi atributi" which means "new attributes cannot appear" in English. This means that during the decomposition of a relation scheme with poor structure, it is not possible to introduce new attributes.

The correct answer states that it is sufficient for the ROLLBACK command to appear only once in order to undo the changes made in all nested transactions. This means that if the ROLLBACK command is executed at the highest level transaction (the one that contains all the nested transactions), it will automatically roll back all the changes made in the nested transactions as well. Therefore, the changes made in the nested transactions will be cancelled.

The correct answer is "sva dodeljena posebna prava nad tabelama, plus kreiranja pogleda nad tim tabelama". This means that CONNECT Privilege includes all the assigned special privileges on tables, as well as the ability to create views on those tables.

The correct answer is that a correlated subquery is executed for each row of the table being processed by the outer query. This means that the execution of the subquery is dependent on the execution of the outer query and is performed for each row individually.

The correct answer states that in order for decomposition to be reversible, the common attribute or set of attributes in the newly created relations should be a candidate key in at least one of the resulting relations. This means that the common attribute(s) uniquely identify the tuples in at least one of the new relations, ensuring that the original relation can be reconstructed from the decomposed relations.

The correct answer is "if it produces the same result as serial execution of transactions." This means that concurrent execution of transactions should not lead to any inconsistencies or conflicts that would change the overall outcome of the transactions compared to executing them one after another in a serial manner. In other words, concurrent execution should not introduce any anomalies or errors in the results.

It is possible to perform locking at various levels during transaction execution, including the complete database, tables, multiple tables, columns, and rows. Locking helps in maintaining data integrity and concurrency control in a multi-user environment.

The two rules of good application design are high cohesion within the same layer and weak coupling between objects in different layers. These rules emphasize the importance of organizing objects within a layer so that they are closely related and work together effectively, while also ensuring that objects in different layers are loosely connected to promote flexibility and maintainability. This approach helps to improve the overall structure and maintainability of the application.

The correct answer states that there is a multiple repetition of individual values of non-key attributes. This means that in the relation, there are non-key attributes that have multiple occurrences of the same value. This can lead to data redundancy and inconsistency, as the same value is repeated unnecessarily, wasting storage space and making it difficult to maintain data integrity.

The explanation for the given correct answer is that a decomposition is considered lossless if the original relation can be obtained by natural join of the newly created relations. This means that when the decomposed relations are combined using the natural join operation, the resulting relation will be exactly the same as the original relation.

The advantages of using a view include simplifying queries, ensuring data confidentiality through access control mechanisms, and the ability to reuse the view in subqueries. Views make it easier to write and execute queries by abstracting complex logic and calculations into a single, simplified view. They also provide a layer of security by allowing access control to be applied to the view, ensuring that only authorized users can access certain data. Additionally, views can be used in subqueries, allowing for more efficient and organized database design.

In a poorly structured relationship, there can be dependencies between attributes of a relation that restrict the values of attributes in tuples. This means that the values of certain attributes are dependent on the values of other attributes within the same relation.

The correct answer states that projection is an operation in relational algebra that forms a new relation by selecting a subset of tuples from the source relation based on a given set of attributes. This means that the projection operation extracts specific attributes from the source relation and creates a new relation with only those attributes. The resulting relation will consist of tuples that contain values only for the selected attributes.

The correct answer states that a restriction operation in relational algebra selects a subset of tuples from the source relation based on a given criterion. This means that the operation filters out tuples that do not meet the specified condition, resulting in a new relation with a subset of tuples.

The correct answer includes all the essential elements of an SQL command for creating tables. It mentions the name of the table, the name of each column, the data type of each column, the constraints for the columns, and the assignment of privileges to users. It also includes the query for obtaining information.

After performing a selection operation, the number of attributes in the resulting relation remains the same as the number of attributes in the original relation. This means that the selection operation does not affect the number of attributes in the relation, and all the attributes from the original relation are retained in the resulting relation.

The correct answer states that accessing data in a database is done by defining nested procedures in the database and calling them from the business logic layer (class). This suggests that the data access is performed through a structured and organized approach, where the database procedures are utilized and called upon by the business logic layer. This approach allows for efficient and controlled access to the data stored in the database.

The introduction of object-oriented programming enabled the complete separation of data from the interface towards data users. It also allowed for the complete separation of data from the logic of their processing. This means that data can be managed and manipulated independently of how they are presented to users or how they are processed. This separation enhances modularity, flexibility, and reusability in software development.

The purpose of the presentation layer in a three-tier application model is to handle the display and user interface aspects of the application. It is responsible for receiving user input, such as data entry, and displaying information to the user, such as data viewing. Additionally, it handles tasks like data deletion and modification. The presentation layer also facilitates querying and creating objects within the application.

Integrated environments have several advantages. They allow for fast development of databases and applications, as they provide all the necessary tools and resources in one place. This saves time and effort in searching for and configuring different software components. Additionally, having everything in one file simplifies the development process and makes it easier to manage and distribute applications. Integrated environments are particularly suitable for building simple applications, as they provide a user-friendly interface and seamless communication with the environment. They also allow for easy modification of applications, enabling developers to quickly make changes and improvements.

The advantages of accessing data in a database from the presentation layer include convenience for simple applications where everything is in one place, such as testing and experimentation applications, suitability for executing simple SQL commands, and ease and speed of implementation. Additionally, it is convenient in case of change or installation of a new version of the database management system (DBMS) as no modifications are required.

Integrated environments have several disadvantages. Firstly, they have a strong coupling with development environments and tools, which means that they are tightly integrated and dependent on specific tools and technologies. This can limit flexibility and make it difficult to switch to different tools or environments. Secondly, communication with the environment can be challenging, leading to difficulties in integrating with external systems or collaborating with other teams. Additionally, maintaining the application can be complicated, especially when it comes to making modifications or expanding its functionality. Finally, integrated environments may suffer from slow and inefficient build processes for databases and applications.