BIM211 – Visual Programming Database Operations 1

Contents Database Structure – Database, Table, Fields, Primary Key, SQL Statements, Select, Insert, Update, Delete Database Operations with C# Data Objects – Designing database, Adding database into solution, Displaying a table, Displaying a single record Database Example 2

Database A database is an integrated collection of logically related records. A database contains tables. The columns of a table is called fields. The rows of a table is called records. The records are accessed by SQL commands. 3

Database Applications A database application is designed using these steps: 1.Determine tables and fields 2.Design database 3.Write a program which reads and manipulates the database In this course, we’ll use Microsoft Access to design databases. 4

Exercise Today, we are going to write a simple database application which displays information about students and courses that students take. 5

1. Determining Tables We need three tables: – Students Contains information about the students, such as ID number, name, birthday, age, etc. – Courses Contains information about the courses, such as course code, course name, instructor, etc. – Enrolment Contains information about which student is enrolled to which course 6

Students Table Students table contains these fields: – ID – First name – Last name – Birthday – Age Notice that these fields are related to a student only (Remember the structs in C) 7

A Sample Students Table IDFirst NameLast NameBirthdayAge 1BaharÇağlar EşrefPazar ErginKaradağ İrfanKarazor SelenDarat

Courses Table Courses table contains these fields: – Course code – Course name – Instructor Adding an ID field will make the database operations simpler: – Course ID 9

A Sample Courses Table Course IDCourse CodeCourse NameInstructor 1BIM111 Introduction to Computer Engineering Muzaffer DOĞAN 2BIM211Visual ProgrammingMuzaffer DOĞAN 3BIM201System SoftwareCüneyt AKINLAR 4BIM309Artificial IntelligenceSedat TELÇEKEN 5BIM213 Data Structures and Algorithms Cüneyt AKINLAR 10

Enrolment Table Enrolment table contains information about the courses taken by each students. It has two fields: – Student ID – Course ID For example, if a record with Student ID = 1 and Course ID = 2, then it means that the student with ID = 1 (Bahar Çağlar) takes the course with ID = 2 (Visual Programming) 11

A Sample Enrolment Table Student IDCourse ID

Primary Key Primary key is the field which uniquely identifies each row in a table A primary key comprises a single column or a set of columns ID field in Students table and Course ID field in Courses table are primary keys Both Student ID and Course ID fields in Enrolment table must be primary keys Always create primary keys for tables. 13

2. Designing Database The database design steps are explained in detail in the next slides The basic steps are – Open Microsoft Access – Create a database file of format Office with the extension *.mdb – Create tables in design view – Enter records – Close MS Access 14

Open MS Access 15

Click Office Button and Select New 16

On the right pane, click Browse button 17

Select a folder, a file name, and Office format with extension *.mdb 18

Click Create Button 19

Right-click Table1 on left-pane and select Design View 20

Give a name to the table and click OK button 21

Write StudentID into the first field 22

Notice the yellow “Primary Key” icon on the left 23

Write “FirstName” into second field and set “Text Size” as 30 24

Write “LastName” into third field and set its “Text Size” as 30 25

Write “BirthDay” to fourth field and set its type as “Date/Time” 26

Write “Age” into fifth field, set its type as “Number” and select “Integer” as its size 27

Close Design View of Students table 28

Click Yes to save the changes 29

Click “Create” tab and select “Table” 30

Right-click Table1 and select Design View 31

Write the name “Courses” and click OK 32

Fill the field names and set their types and sizes. Click Close button. 33

Click Yes to save the changes 34

Give the command Create - Table 35

Right-click Table1 and select Design View 36

Write Enrolment as the table name and click OK 37

“StudentID”, Number, Long Integer 38

“CourseID”, Number, Long Integer 39

Using mouse, select both StudentID and CourseID fields 40

Click “Primary Key” button and notice that both fields become primary keys 41

Close the Design View of Enrolment table 42

Click Yes to save the changes 43

Double-click Students table 44

Fill the records (don’t write anything into StudentID field, it is automatically filled) 45

Double-click Courses table and enter the records 46

Double-click Enrolment table and enter the records 47

Close the MS Access window 48

3. Writing the Program a)Adding database file into solution b)Displaying students c)Adding new student d)Changing student info e)Deleting a student f)Displaying all courses a student take 49

a) Adding Database File into Solution 50

Summary of the Steps Create a new project Copy the database file into the solution folder Add the database file into the solution in Visual Studio

Copy database file into solution folder 52

Right-click project name, click Add, click Existing Item… 53

Filter Data Files, Select the database file and click Add 54

Select all tables and click Finish 55

Database file and automatically generated files are displayed in Solution Explorer 56

After you build your program, you’ll see some additional project-related objects at the top of the toolbox 57

b) Displaying Students 58

The data-related objects are located under the “Data” menu of the toolbox: 59

Drag & Drop a DataGridView object 60

Choose Students as the Data Source 61

Execute the Program 62

What to Notice? Notice that... – We didn’t write any code! – When we select Data Source, some controls are added to the form automatically by Visual Studio! – Some codes are added into Load event handler of the form automatically by Visual Studio! 63

Which controls are added? 64

Which code is added? 65

Controls studentsTableAdapter – The interface between program and database schoolDataSet – All data is written into this dataset studentsBindingSource – Binds data to the controls (e.g. DataGridView) on the form 66

Controls 67 Database Table Adapter Data Set Binding SourceForm

The Code this.studentsTableAdapter.Fill(this.schoolDataSet.Students); 68 Controls added into solution automatically by Visual Studio The method which acquires data from database The table which is used to store query results from Students table of the database

Acquiring Data of One Student All data acquirement operations are done by TableAdapter object Fill method is the method which brings all data from the table If you want to get only one student’s data, you need to create a new query in the TableAdapter object 69

Click on the triangle on table adapter object and select Add Query command 70

Write FillByStudentID as query name and click Query Builder button 71

Go to the Filter column of StudentID row and write “=?” and click OK 72

Query Builder All data are acquired from database via SQL commands Query builder makes writing SQL commands easier By clicking Execute button, you can display the result of your query Notice that the SQL command is changed after you write “=?” into the Filter column Here, “?” represents a parameter for the query 73

Click OK to return to Visual Studio 74

A ToolStrip is automatically added into the form 75

A new code which uses the new FillByStudentID method is added into the codes 76

Run the program, write a number into StudentID box, and click FillByStudentID button 77 Only the student with the selected ID is displayed

About the ToolStrip Generally, the ToolStrip which is added by Visual Studio is not wanted You can simply delete the ToolStrip and write your own code Click on the ToolStrip icon below the form (near other automatically added controls) and press Delete button from the keyboard 78

Displaying One Student’s Info by Code Place a button on the form and write the following code in its Click event handler: 79 this.studentsTableAdapter.FillByStudentID( this.schoolDataSet.Students, 3); In the code above, the Students table in the data set is filled by the FillByStudentID method of the table adapter with the data of the student with ID 3.

Execution of the Program: 80

When “One Student” button is clicked: 81

Is it displayed automatically? Notice that we only filled the data set and we didn’t write any code to display new data in DataGridView object So, how was data displayed in DataGridView? This task is accomplished by the Binding Source object. So, you just need to bring and write data into the data set and it is automatically displayed in the controls on the form 82

Other Methods in Table Adapter Object The studentsTableAdapter control has some useful methods: – Fill() : Get data from database – Insert() : Add a new record to the database – Update() : Change an existing record – Delete() : Delete an existing record These methods correspond to the SQL commands of types Select, Insert, Update, and Delete respectively 83

SQL Command Types and Corresponding Methods SQL Command TypeTable Adapter Method SELECTFill() FillByStudentID() FillByStudentName() etc. INSERTInsert() UPDATEUpdate() DELETEDelete() 84

c) Adding New Student (will be covered in next week) 85

d) Changing Student Info (will be covered in next week) 86

e) Deleting a Student (will be covered in next week) 87

f) Displaying All Courses a Student Take (will be covered in next week) 88