Chapter 4 Intermediate SQL Joins Chapter 4 Intermediate
- Slides: 16
Chapter 4: Intermediate SQL Joins
Chapter 4: Intermediate SQL n Join Expressions n Views n Transactions n Integrity Constraints n SQL Data Types and Schemas n Authorization
JOINS
Job Interview Question
Joined Relations n Join operations take two relations and return as a result another relation. n A join operation is a Cartesian product which requires that tuples in the two relations match (under some condition). It also specifies the attributes that are present in the result of the join n The join operations are typically used as subquery expressions in the from clause
Types of Joins n [Inner] Join n [Natural] Outer Joins l [Natural] Left Outer Join l [Natural] Right Outer Join l [Natural] Full Outer Join
A Picture is Worth…
Recall Join - Using n select name, title from (instructor natural join teaches) join course using(course_id);
Join operations – Example n Relation course n Relation prereq n Observe that prereq information is missing for CS-315 and course information is missing for CS-347
Outer Join n An extension of the join operation that avoids loss of information. n Computes the join and then adds tuples form one relation that does not match tuples in the other relation to the result of the join. n Uses null values. n Example query l Find all courses without a prerequisite.
Left Outer Join n select * course natural left outer join prereq n select * from course natural left outer join prereq
Right Outer Join n select * course natural right outer join prereq
Joined Relations n Join operations take two relations and return as a result another relation. n These additional operations are typically used as subquery expressions in the from clause n Join condition – defines which tuples in the two relations match, and what attributes are present in the result of the join. n Join type – defines how tuples in each relation that do not match any tuple in the other relation (based on the join condition) are treated.
Full Outer Join n course natural full outer join prereq
Joined Relations – Examples n course inner join prereq on course_id = prereq. course_id n What is the difference between the above, and a natural join? n course left outer join prereq on course_id = prereq. course_id
Joined Relations – Examples n course natural right outer join prereq n course full outer join prereq using (course_id)
- Inner join
- Joins two words together
- Adjective b
- Random sampling over joins revisited
- Joins words or groups of words
- Joins words or word groups
- Joins
- Dna ligase joins ends and repairs nicks
- Monhum
- A _________bond joins amino acids together.
- A _________bond joins amino acids together.
- Set serveroutput on
- Sql developer unit testing
- Cost of retained earnings
- Kieso chapter 17
- Amortization expense formula
- Chapter 13 intermediate accounting