1. SQL – Basic Queries By: Ranmale.V.A

2. SQL Introduction Structured Query Language
Originally called SEQUEL from Structured English QUEry Language
SQL has a standard
SQL provides both
Data Definition Language (DDL)
Data Manipulation Language (DML)
DBMS may provide higher level approach, but SQL is important for tougher queries, using host programming or web programming.

3. SQL - Basic Queries
Basic form of SQL query: SELECT <attribute list> FROM <table list> [WHERE <condition>]
<attribute list> would be a list of columns separated by commas, etc.
[ ] enclose optional clauses
SQL is not case sensitive

4. SQL - Basic Queries -Conceptually
SELECT <attribute list> FROM <table list> [WHERE <condition>]
Step 1: Make “long” rows by combining rows from the various tables in FROM clause in every possible way – each row in first table with each row in second table with each row in third table, etc.
Step 2: Keep the long rows that satisfy WHERE condition.
Step 3: Keep only columns specified in SELECT.

5. SQL - Basic Queries
Example: Pose a query to get the names of all students: SELECT LastName, FirstName FROM Students

6. SQL - Basic Queries (cont.)
Names of freshmen students

7. SQL - Basic Queries (cont.)
Names of students from Fredericksburg

8. SQL - Basic Queries (cont.)
Names of students from Fredericksburg

9. SQL - Basic Queries (cont.)
Names of students from Fredericksburg

10. SQL - Basic Queries (cont.)
Dump the Students table: SELECT * FROM Students
Get names of departments having majors in our database
SELECT Department FROM Majors
SELECT DISTINCT Department FROM Majors

11. SQL - Basic Queries –Joining tables based on foreign key
Connecting students with their advisors: we need to have AdvisorID = FacultyID
Students(StudentID,FirstName, LastName, ClassYear, City, State, Zip, BirthDate, AdvisorID, Term)
Faculty (FacultyID, FirstName, LastName, Phone, )

12. SQL - Basic Queries –Joining tables based on foreign key
Connecting majors with their department chairs: we need to have ChairID = FacultyID
Majors(MajorID, MajorName, Department, ChairID)
Faculty (FacultyID, FirstName, LastName, Phone, )

13. SQL - Basic Queries – Joining tables
Student last name, advisor last name
OR (aliasing)

14. SQL - Basic Queries – Joining tables

15. SQL - Basic Queries –Joining tables based on intermediate table
Connecting students with their interests: we need to have Students.StudentID = StudentInterest.StudentID AND StudentInterest.InterestID = Interests.InterestID
Students(StudentID,FirstName, LastName, ClassYear, City, State, Zip, BirthDate, AdvisorID, Term)
StudentInterest(StudentID, InterestID)
Interests(InterestID, InterestName, Category, URL)

16. SQL - Basic Queries –Joining tables based on intermediate table
Connecting students with majors: we need to have Students.StudentID = StudentMajor.StudentID AND StudentMajor.MajorID = Majors.MajorID
Students(StudentID,FirstName, LastName, ClassYear, City, State, Zip, BirthDate, AdvisorID, Term)
StudentMajor(StudentID, MajorID)
Majors(MajorID, MajorName, Department, ChairID)

17. SQL - Basic Queries – Joining tables (cont.)
Student last name, first name, name of NFL team student is interested in.

18. SQL - Basic Queries – Joining tables (cont.)