Using sub query

Sub query A query inside another query

Examples of Subqueries

Example 1 Retrieve the name of all employees who have dependents

Example 1(continued) In this example: the sub query is used in the where clause. The example goal: to retrieve the ssn for the employees who have at least one dependent.

Example 2 Retrieve the name of all employees who works on two projects

Example 2 In this example: the sub query is used in the having clause The example goal: to retrieve the number of projects for each employee who works on at least one project in the works_on table.

Example 3 Retrieve the name of all employees with the department name each employee works on.

Example 3 In this example: the sub query is used in the select clause. The example goal: to retrieve the name of the department that each employee works on.

Example 4 Retrieve all employees who works on all projects

Example 5 Update the location of all projects controlled by Headquarter department to be in New york Before updateAfter update

Example 6 Delete all employees in works_on table who works on all the projects located in Belliare After delete Before delete

Backup and restore a database

Backup a database Step 1

Backup a database Step 2: click ok to backup The location for the backed up database

Restore a database Step 1:

Restore a database Step 2: choose from device

Restore a database Step 3: add the database backup you want to restore

Restore a database Step 4: choose the location of the database backup you want to restore.

Restore a database Step 5: Now press OK for the last two interfaces Check the check box Choose your database

Restore a database Step 6: add the red colored text before the database location to correct the location of the database C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\Data\clinic.mdf C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\Data\clinic_1.LDF

Restore a database Step 7: Now your database created successfully The restored database