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Results After Creating Foreign Key Constraints and Foreign Keys


Figure 3.31. Select Delete and Update mode

Results after creating primary key and foreign key constraints

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Figure 3.32. The result after creating foreign key and foreign key constraints

- Delete foreign key constraint: Select foreign key constraint name/Select Delete/Select OK.

3) Unique constraints

- Create unique constraint:

Step 1: Select table name/Select Indexes/Select New Index.

Figure 3.33. Create unique constraint

Step 2: Enter the constraint name in the Index Name section/Select the Index type in the Index Type section/Check the Unique selection box/Select the Add button.


Figure 3.34. Enter a name for the unique constraint

Step 3: Select the check box in the field that needs to create a constraint/select OK/Select OK.

Figure 3.35. Select the field for which you want to create a unique constraint

Result after creating unique constraint

Figure 3.36. Unique constraint creation result

- Delete unique constraint: Select unique constraint name/Select Delete/Select OK.

4) Check constraints

- Create check constraint:


Step 1: Select table name/Select Constraints/Right click/Select New Constraints.

Figure 3.37. Create a check constraint

Step 2: Enter a name for the constraint in the Name section/ Select the … button in the Expression section.

Figure 3.38. Enter a name for the check constraint

Step 3: Enter constraint conditions/Select OK

Figure 3.39. Enter conditions for check constraints

Result after creating check constraint


Figure 3.40. Result of creating check constraint

- Delete check constraint: Select check constraint name/Select Delete/Select OK.

5) Default constraints

Select the field name for which you want to create a default constraint/Enter the default value in the Default Value or Binding section.

Figure 3.41. Create default constraints

Result after creating default constraint

Figure 3.42. Default constraint creation result

- Delete default constraint: Select default constraint name/Select Delete/Select OK.


3.2.3. Working with data tables

1) Connect the data tables

After successfully designing the data tables, we can create connections between the data tables.

Step 1: Select database/Select Database Diagrams/Select New Database Diagrams.

Figure 3.43. Creating connections between tables

Step 2: Select table/Select Add button. When you have selected the tables to create a connection, select Close button.

Figure 3.44. Select data tables

Step 3: Select the connection field of the first table and drag and drop it into the connection field of the second table.


Figure 3.45. Creating a connection

Step 4: Check the connection field/ Select OK.

Figure 3.46. Check connection field

Step 5: Confirm the connection/ Select OK. The connection between the tables is then created (Figure 3.30).

Figure 3.47. Confirming the connection


Figure 3.48. The connection is created.

Step 5: Save the connection. Select the Save button/Enter the connection name/OK.

Figure 3.49. Save connection

2) Change table structure

- Use MS tools

Step 1: Select database name/Select table name/Right click/Select Design.

Figure 3.50. Changing the structure of the data table

Step 2: Edit the table structure.

Figure 3.51. Redesigning the data table

Step 3: Select the Save button on the toolbar to save the changes. Select the Yes button to confirm the structure modification.


Figure 3.52. Confirming the data table redesign

- Use T-SQL statement

Step 1: Select the New Query button , the New Query window appears. Step 2: Declare the statement to change the data table structure (Alter Table). Step 3: Select the button to check the T-SQL statement.

Step 4: Select the button to execute the command to change the data table structure.

3) Clear table

- Use MS tools

Step 1: Select database name/Select table name/Right click/Select Delete.

Figure 3.53. Delete data table

Step 2: Select the OK button.

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