Does the table contain any information. Database

This article contains brief information about databases: what they are, how they can be useful, what are their functions individual elements. The terminology used here is specific to Microsoft Access, but the concepts described are applicable to any database.

In this article:

What is a database?

Databases are a tool for collecting and structuring information. The database can store data about people, products, orders, and much more. Many databases start out as a small list in a text editor or spreadsheet. As the amount of data in the list increases, inconsistencies and redundant information gradually appear. Information displayed as a list becomes incomprehensible. In addition, the ways in which subsets of data can be searched and displayed are limited. As soon as these problems start to appear, we recommend that you move all your information to a database created in a database management system (DBMS) such as Access.

A computer database is a repository of objects. There can be more than one table in one database. For example, an inventory tracking system that uses three tables is not three databases, but one. In an Access database (unless specifically configured to work with data or code from a different source), all tables are stored in a single file along with other objects such as forms, reports, macros, and modules. Database files created in the Access 2007 format (which is also used by Access 2016, Access 2013, and Access 2010) use the .accdb file extension, while database files created in earlier versions of Access use the .mdb file extension. With Access 2016, Access 2013, Access 2010, and Access 2007, you can create files in the formats of earlier versions of the application (such as Access 2000 and Access 2002-2003).

Using Access allows you to:

add new information to the database, such as a new inventory item;

change the information already in the database, for example, move the article;

delete information, for example, if the article has been sold or disposed of;

organize and view data different ways;

share data with other people using reports, e-mail messages, an intranet, or the Internet.

Access database elements

Below are short descriptions elements of a standard Access database.

tables

A database table is similar to a spreadsheet - both there and there information is located in rows and columns. Therefore, importing a spreadsheet into a database table is usually quite easy. The main difference is how the data is structured.

In order for the database to be as flexible as possible and to avoid redundant information appearing in it, the data should be structured in the form of tables. For example, if we are talking about a table with information about company employees, you do not need to enter data about the same employee more than once. Product data should be stored in a separate table, as well as data on company branches. This process is called normalization.

Rows in a table are called records. The record contains blocks of information. Each entry consists of at least one field. The fields correspond to the columns in the table. For example, in a table called "Employees", each record contains information about one employee, and each field contains a separate category of information, such as first name, last name, address, etc. Fields are allocated to certain types of data, such as text, numbers, or other data.

Records and fields can be described differently. Imagine an old library card catalog. Each card in the cabinet corresponds to entry in the database. Information blocks on the card (author, book title, etc.) correspond to fields in the database.

For more information about tables, see Tables overview.

Forms

Forms provide a user interface for entering and editing data. Forms often contain command buttons and other controls that perform various functions. You can create a database without using forms by simply editing existing information in Access tables. However, most users prefer to use forms to view, enter, and edit information in tables.

Command buttons specify the data that should appear in the form, open other forms and reports, and perform a number of other tasks. For example, there is a "Customer Form" in which you work with customer data. And there may be a button in it, by pressing which an order form opens, with the help of which you enter information about an order made by a specific client.

Forms also provide the ability to control how users interact with database information. For example, you can create a form that displays only certain fields and can only perform a limited number of operations. This ensures the security and correct entry of data.

For more information about forms, see the Forms article.

Reports

Reports are used to format, summarize, and display data. Typically, the report allows you to find the answer to a specific question, such as "How much profit did our customers bring us this year?" or "What cities do our clients live in?" Reports can be formatted to display information in the most readable way.

The report can be generated at any time and will always display the current database information. Reports are usually formatted so that they can be printed, but they can also be viewed on screen, exported to other programs, or attached to email messages.

Requests

Queries can perform many functions in a database. One of their main functions is to find information in tables. The required information is usually contained in several tables, but if you use queries, it can be viewed in one. In addition, queries make it possible to filter data (for this, search criteria are set) so that only the necessary records are displayed.

So-called "updatable" queries are also used, which make it possible to edit the data found in the main tables. When working with an updatable query, keep in mind that edits are made to the main tables, not just the query table.

There are two main types of requests: select and change requests. The select query only finds data and provides access to it. The results of such a query can be viewed on the screen, printed or copied to the clipboard, or used as a record source for a form or report.

With the help of a change request, as the name implies, you can perform certain operations on the found data: create tables, add information to existing tables, and update or delete data.

For more information about queries, see Introduction to queries.

Macros

Macros in Access are like a simplified programming language that can be used to make a database more functional. For example, if you add a macro to a command button on a form, it will run every time the button is clicked. Macros consist of commands that perform specific tasks: open reports, run queries, close a database, etc. Using macros, you can automate most of the operations that you do manually in the database, and thus save a lot of time .

For more information about macros, see Access Programming Overview.

Modules

Like macros, modules are objects that can be used to make a database more functional. However, if you compose macros in Access by selecting from a list of macros, modules are created in Visual Basic for Applications (VBA). Modules are collections of descriptions, instructions, and procedures. There are class modules and standard modules. Class modules are associated with specific forms or reports and typically include procedures that work only with those forms or reports. The standard modules contain general procedures, not associated with any object. Standard modules, unlike class modules, are listed Modules in the navigation area.

1. Database is:

a set of data organized according to certain rules;

a set of programs for storing and processing large amounts of information;

an interface that supports filling and manipulating data;

certain set of information.

2. The most common in practice are:

distributed databases;

hierarchical databases;

network databases;

relational databases.

3. Tables in databases are intended:

for storing database data;

to perform complex programming actions.

4. What requests are for:

for storing database data;

for selection and processing of database data;

to enter database data and view them;

for automatic execution of a group of commands;

to perform complex program actions;

to output the processed database data to the printer?

5. What forms are for:

for storing database data;

for selection and processing of database data;

to enter database data and view them;

for automatic execution of a group of commands;

to perform complex programming actions?

6. In what mode does the user work with the database:

in the design;

in amateur;

in the given;

in operationalm?

7. In which dialog box are links created between fields of database tables :

link table;

link diagram;

data schema;

data table?

8. Without which objects a database cannot exist:

without modules;

without reports;

without tables;

without forms;

without macros;

no requests?

9. Which elements of the table store the database data:

in the fields;

in lines;

in columns;

in records;

in cells?

10. Does a table contain any information in which there is not a single record?

an empty table does not contain any information;

an empty table contains information about the structure of the database;

an empty table contains information about future entries;

A table without records cannot exist.

11. Does a table with no fields contain any information?

contains information about the structure of the database;

does not contain any information;

a table without fields cannot exist;

contains information about future entries.

12. Search keys in database management systems (DBMS) are called :

the range of records in the database file in which the search is performed;

logical expressions that define search conditions;

fields by the value of which the search is carried out;

numbers of records that meet the search conditions;

the number of the first record in order that satisfies the search criteria?

What elements of the table store database data?

Without which objects can a database not exist?

In which dialog box are links created between fields of database tables?

What are macros for?

What are the reports for?

What are forms for?

What are requests for?

Which of the following is not an Access object?

a) modules;

b) tables;

c) macros;

D) keys;

f) reports;

g) requests.

a) to store database data;

f) to output the processed database data to the printer.

a) to store database data;

b) for the selection and processing of database data;

C) to enter database data and view them;

d) for automatic execution of a group of commands;

e) to perform complex program actions;

a) to store database data;

b) for the selection and processing of database data;

c) to enter database data and view them;

d) for automatic execution of a group of commands;

D) to output data to a printing device;

a) to store database data;

b) for the selection and processing of database data;

c) to enter database data and view them;

D) for automatic execution of a group of commands;

e) to perform complex program actions.

a) link table;

b) link diagram;

C) data schema;

d) data table.

a) without modules;

b) no reports;

C) without tables;

d) without forms;

e) without macros;

e) no requests.

a) in the fields;

b) in the lines;

c) in columns;

D) in cells.

The development of the design of the switchgear begins after they have completely decided on the scheme electrical connections, selected electrical devices (including instrument transformers, arresters (discharge switch), grounding, etc.) and connecting conductors, the accepted layout of the main and auxiliary structures at the station (substation) site.

The scope of the design development of the reactor plant includes: selection of the reactor design type; selection of the type of internal layout of the electrical equipment of the switchgear; sketch of the switchgear layout - folding the sketches of the switchgear cells, the filling scheme and the plan of the switchgear; compilation of working drawings.

AT modern conditions there is no need to approach the development of the design of each RP as the design of an original new facility in all its details. Leading design organizations have developed typical reactor plant designs with respect to the main electrical circuits, which are used today in power plants and substations. Over time, they are replaced by new, more advanced designs.

Typical Constructive decisions are the basis for the development of switchgear designs when designing a specific power plant (substation). Only for hydroelectric power plants, where the dimensions of the room that is allocated in the engine room for electrical equipment, are very dependent on the type and power of the hydroelectric power station, it is difficult to use typical switchgear designs. Therefore, for each HPP, an individual design development of generator voltage switchgear is carried out.

In the general case, the final decision regarding the design of the reactor plant is made on the basis of a technical and economic comparison of a number of layout options that have been sketched out.

Switchgears must meet a number of requirements fixed in the PUE. The main ones are reliability, efficiency, convenience and safety in maintenance, safety for persons who are behind the switchgear, fire safety, and the possibility of expansion.

Reliability in operation means a low probability of occurrence of equipment damage and short circuit in the switchgear and localization of damage, if it does occur. Phenomena accompanying the normal operation of the switchgear, such as electrodynamic forces, heating, gas emissions during short circuit disconnection, etc., should not lead to damage to the equipment and the occurrence of a short circuit in the switchgear.

Requirement economy provides, if possible, smaller switchgear dimensions (area, volume of the building), capital costs and construction time.

Only maintenance personnel - operational and repair personnel (if there is an appropriate permit to repair work). There must be an excluded possibility of accidental penetration of unauthorized persons into the territory of the reactor facility, as well as their dangerous approach to the output electrical communications.

For operating personnel, it is necessary to provide safety and convenience review of equipment, performing switching and work from eliminating minor problems, for maintenance personnel - the safety and convenience of repairing and replacing equipment when power is removed only from the connection to which the equipment being repaired belongs. To replace the equipment, it must be possible to conveniently transport it within the territory (premises) of the reactor facility.

Fire safety lies in the low probability of a fire in the reactor facility and the prevention of its spread in the event of a fire.

Requirement expandability means the possibility of connecting new connections to the switchgear.

Test on the topic "Databases"

^ 1. Database is:

1. 
   a set of data organized according to certain rules;
2. 
   a set of programs for storing and processing large amounts of information;
3. 
   an interface that supports filling and manipulating data;
4. 
   certain set of information.

^ 2. The most common in practice are:

1. 
   distributed databases;
2. 
   hierarchical databases;
3. 
   network databases;
4. 
   relational databases.

^ 3. The most accurate analogue of a relational database can be:

1. 
   unordered set of data;
2. 
   vector;
3. 
   genealogical tree;
4. 
   two-dimensional table.

^ 4. Tables in databases are intended:

1. 
   for storing database data;
2. 
   
3. 
   
4. 
   
5. 
   to perform complex programming actions.

^ 5. Which of the following is not an Access object:

1. 
   modules;
2. 
   tables;
3. 
   macros;
4. 
   keys;
5. 
   forms;
6. 
   reports;
7. 
   requests?

^ 6. What requests are for:

1. 
   for storing database data;
2. 
   for selection and processing of database data;
3. 
   to enter database data and view them;
4. 
   for automatic execution of a group of commands;
5. 
   to perform complex program actions;
6. 
   to output the processed database data to the printer?

^ 7. What forms are for:

1. 
   for storing database data;
2. 
   for selection and processing of database data;
3. 
   to enter database data and view them;
4. 
   for automatic execution of a group of commands;
5. 
   

^ 8. What are the modules for:

1. 
   for storing database data;
2. 
   for selection and processing of database data;
3. 
   to enter database data and view them;
4. 
   for automatic execution of a group of commands;
5. 
   to perform complex programming actions?

^ 9. What macros are for:

1. 
   for storing database data;
2. 
   for selection and processing of database data;
3. 
   to enter database data and view them;
4. 
   for automatic execution of a group of commands;
5. 
   to perform complex programming actions?

^ 10. In what mode does the user work with the database:

1. 
   in the design;
2. 
   in amateur;
3. 
   in the given;
4. 
   in operational?

^ 11. In which dialog box are links created between fields of database tables:

1. 
   link table;
2. 
   link diagram;
3. 
   data schema;
4. 
   data table?

^ 12. Why, when closing a table, Access does not offer to save the entered data:

1. 
   program flaw;
2. 
   because the data is stored immediately after being entered into the table;
3. 
   because the data is only saved after closing the entire database?

^ 13. Without which objects a database cannot exist:

1. 
   without modules;
2. 
   without reports;
3. 
   without tables;
4. 
   without forms;
5. 
   without macros;
6. 
   no requests?

^ 14. Which elements of the table store the database data:

1. 
   in the fields;

1. 
   in lines;
2. 
   in columns;
3. 
   in records;
4. 
   in cells?

15. Does a table contain any information in which there is not a single record?

1. 
   an empty table does not contain any information;
2. 
   an empty table contains information about the structure of the database;
3. 
   an empty table contains information about future entries;
4. 
   A table without records cannot exist.

16. Does a table with no fields contain any information?

1. 
   contains information about the structure of the database;
2. 
   does not contain any information;
3. 
   a table without fields cannot exist;
4. 
   contains information about future entries.

^ 17. What is the peculiarity of the "counter" field?

1. 
   
2. 
   
3. 
   the data is stored not in the field, but in another place, and only a pointer to where the text is located is stored in the field;
4. 
   has a limited size;
5. 
   has the property of automatic growth.

^ 18. What is the peculiarity of the MEMO field?

1. 
   serves to enter numerical data;
2. 
   serves to enter real numbers;
3. 
   the data is stored not in the field, but in another place, and only a pointer to where the text is located is stored in the field;
4. 
   has a limited size;
5. 
   has the property of automatic growth.

^ 19. What field can be considered unique?

1. 
   a field whose values ​​cannot be repeated;
2. 
   a field that has a unique name;
3. 
   the field whose value has the increment property.

20. Search keys in database management systems (DBMS) are:

1. 
   the range of records in the database file in which the search is performed;
2. 
   logical expressions that define search conditions;
3. 
   fields by the value of which the search is carried out;
4. 
   numbers of records that meet the search conditions;
5. 
   the number of the first record in order that satisfies the search criteria?

Test on the subject of DBMS

^ 1. From the given definitions, select a definition:

1. What is a database?

2. What is a DBMS?

1. A program with which data is entered and any actions are performed on this data: viewing, sorting, searching, etc.

2. A file that stores data in a special format.

^ 2. From the proposed definitions of DBMS data models, select the definitions that correspond to:

1. Hierarchical.

2. Network.

3. Relational.

1. The data model is based on the principle of interconnected tables.

2. One type of object is the main one, all underlying ones are subordinate.

3. Any type of data can be master and slave at the same time.

^ 3. Which of the following DBMS is included in the popular Microsoft Office package?

1 Lotus Approach.

2.Microsoft Access.

3. Visual FoxPro.

4 Borland Paradox.

5 Borland dBase.

4. The database contains information about school students: last name, grade, test score, practical task score, total score. What type should the TOTAL POINTS field be?

1. text 2. boolean 3. numeric 4. any type 5. date

5 - 6 The relational database is defined by the table:

(club = "Sparta" OR club = "Rotor") and NOT (gender = "female")?

1. 3,5 2. 1,3,5 3. 2,3,4,5 4. 2,4 5. there are no such records

6. Which records will be selected by the condition:

Sport = "skiing" OR gender = "female" AND age
1. 2,3,4,5,6 2. 3,5,6 3. 1,3,5,6

4. no such records 5. 2,3,5,6

^ 7. The database contains information about dogs from the kennel club: name, breed, date of birth, gender, number of medals. what type should the fields be?

1. text, text, numeric, text, numeric

2. text, text, date, text, numeric

3. textual, textual, date, boolean, numeric

4. text, text, numeric, boolean, numeric

5. text, text, date, boolean, text

8 - 9 The relational database is defined by the table:

^ 8. Select the main key for the table (assuming that there is one room in the cinema)

2. cinema + start of the session

3. title + session start

4. cinema

5. start a session

^ 9. In what order will the records go if they are sorted by two keys:

name + cinema in ascending order?

1. 
   1,5,3,4,7,2,6
2. 
   5,1,3,7,4,2,6
3. 
   6,2,4,7,3,1,5
4. 
   6,2,7,4,3,1,5
5. 
   2,5,4,7,1,3,6

^ Test on the topic “Databases. DBMS"

1. 
   An example of a factual database (DB) is:

1. 
   ^ An example of a document database is:

1. 
   ^ The search keys in the DBMS are called:

B) logical expressions that define the search conditions;

C) fields by the value of which the search is carried out;

D) numbers of records that meet the search conditions;

E) the number of the first record in order that satisfies the search conditions.

1. 
   ^ Sorting is called:

B) the process of partial ordering of a certain set;

C) any process of permutation of elements of some set;

D) the process of linear ordering of some set;

E) the process of selecting elements of a set that satisfy a given condition.

1. 
   ^ The database is:

B) a set of programs for storing and processing large amounts of information;

C) an interface that supports filling and manipulating data;

D) a certain set of information.

1. 
   ^ An example of a hierarchical database is:

B) a directory of files stored on disk;

B) train schedule;

D) spreadsheet.

1. 
   ^ In a hierarchical database, a set of data and relationships between them is described by:

B) network diagram;

B) tree structure;

D) a set of tables.

1. 
   ^ A network database assumes such an organization of data in which:

B) relationships between data are described in the form of a tree;

C) in addition to vertical hierarchical relationships (between data), there are also horizontal ones;

D) relationships between data are reflected in the form of a set of several tables.

1. 
   ^ The most common in practice are:

B) hierarchical databases;

C) network databases;

D) relational databases.

1. 
   ^ The most accurate analogue of a relational database can be:

B) vector;

B) a family tree;

D) two-dimensional table.

1. 
   ^ Relational database fields:

B) automatically numbered;

C) are named according to the rules specific to each particular DBMS;

D) are numbered according to the rules specific to each particular DBMS.

1. 
   ^ The structure of a relational database (DB) file is completely defined by:

B) a list of field names indicating their width and types;

C) the number of records in the database;

1. 
   ^ The structure of a relational database (DB) file changes when:

B) deleting one record;

C) deleting several records;

D) deleting all records.

1. 
   ^ A relational database (DB) file record may contain:

B) exclusively homogeneous information (data of only one type);

C) only textual information;

D) exclusively numerical information.

1. 
   ^ In the file field of a relational database (DB) can be written:

B) both numerical and textual data at the same time;

C) data of only one type;

D) only the time of creation of records.

1. 
   ^ What data type is the value of the expression 0.7–3>2

B) logical;

B) string;

D) whole.

1. 
   ^ The database management system is:

B) a set of programs that ensures the operation of all hardware devices of a computer and user access to them;

C) an application program for processing texts and various documents;

D) shell operating system, which allows you to more comfortably work with files.

1. 
   ^ The main functions of the DBMS do not include:

B) creating the structure of the database file;

C) initial input, replenishment, editing of data;

D) search and sorting of data.

1. 
   Suppose some database contains the fields SURNAME, YEAR OF BIRTH, INCOME. When searching by condition:

A) those with an income of less than 3500 and those born in 1958 and later;

B) having an income of less than 3500 and older than those who were born in 1958;

C) those with an income of less than 3,500 or those born in 1958 or later;

D) having an income of less than 3500 and born in 1959 and later.

1. 
   Suppose some database contains the fields SURNAME, YEAR OF BIRTH, INCOME. Which of the following records of this database will be found when searching by the condition YEAR OF BIRTH>^ 1958 OR INCOME

B) Ivanov, 1956, 2400;

C) Sidorov, 1957, 5300;

D) Kozlov, 1952, 1200.

1. 
   ^

2 Sidorov, 1957, 5300;

3 Petrov, 1956, 3600;

4 Kozlov, 1952, 1200;

^ Which of the records will change places when sorting in ascending order of this database, if it is carried out by the first field:

D) 2 and 3.

1. 
   ^ Suppose some database is described by the following list of records:

2 Sidorov, 1957, 5300;

3 Petrov, 1956, 3600;

4 Kozlov, 1952, 1200;

^ In what order will these records be placed after sorting in ascending order, if it is carried out by the second field:

B) 2, 1, 3, 4;

» [Teacher][Tests][Databases]

DATABASE

TEST

1. Database is:

1. a set of data organized according to certain rules;
2. a set of programs for storing and processing large amounts of information;
3. an interface that supports filling and manipulating data;
4. certain set of information.

2. The most common in practice are:

1. distributed databases;
2. hierarchical databases;
3. network databases;
4. relational databases.

3. The most accurate analogue of a relational database can be:

1. unordered set of data;
2. vector;
3. genealogical tree;
4. two-dimensional table.

4. Tables in databases are intended:

1. for storing database data;
2. to perform complex programming actions.

5. Which of the following is not an Access object:

1. modules;
2. tables;
3. macros;
4. keys;
5. forms;
6. reports;
7. requests?

6. What requests are for:

1. for storing database data;
2. for selection and processing of database data;
3. to enter database data and view them;
4. for automatic execution of a group of commands;
5. to perform complex program actions;
6. to output the processed database data to the printer?

7. What forms are for:

1. for storing database data;
2. for selection and processing of database data;
3. to enter database data and view them;
4. for automatic execution of a group of commands;

1. for storing database data;
2. for selection and processing of database data;
3. to enter database data and view them;
4. for automatic execution of a group of commands;
5. to perform complex programming actions?

9. What macros are for:

1. for storing database data;
2. for selection and processing of database data;
3. to enter database data and view them;
4. for automatic execution of a group of commands;
5. to perform complex programming actions?

10. In what mode does the user work with the database:

1. in the design;
2. in amateur;
3. in the given;
4. in operational?

11. In which dialog box are links created between fields of database tables:

1. link table;
2. link diagram;
3. data schema;
4. data table?

12. Why, when closing a table, Access does not offer to save the entered data:

1. program flaw;
2. because the data is stored immediately after being entered into the table;
3. because the data is only saved after closing the entire database?

13. Without which objects a database cannot exist:

1. without modules;
2. without reports;
3. without tables;
4. without forms;
5. without macros;
6. no requests?

14. Which elements of the table store the database data:

1. in the fields;
2. in lines;
3. in columns;
4. in records;
5. in cells?

15. Does a table contain any information in which there is not a single record?

1. an empty table does not contain any information;
2. an empty table contains information about the structure of the database;
3. an empty table contains information about future records;
4. A table without records cannot exist.

16. Does a table with no fields contain any information?

1. contains information about the structure of the database;
2. does not contain any information;
3. a table without fields cannot exist;
4. contains information about future entries.

17. What is the peculiarity of the "counter" field?

1. has a limited size;

18. What is the peculiarity of the "memo" field?

1. serves to enter numerical data;
2. serves to enter real numbers;
3. the data is stored not in the field, but in another place, and only a pointer to where the text is located is stored in the field;
4. has a limited size;
5. has the property of automatic growth.

1. a field whose values ​​cannot be repeated;
2. a field that has a unique name;
3. the field whose value has the increment property.

20. Search keys in database management systems (DBMS) are:

1. the range of records in the database file in which the search is performed;
2. logical expressions that define search conditions;
3. fields by the value of which the search is carried out;
4. numbers of records that meet the search conditions;
5. the number of the first record in order that satisfies the search criteria?

KEY