Difference between revisions of "DD Class11"
(→Sub Query) |
(→Sub Query) |
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| Line 105: | Line 105: | ||
</sql> | </sql> | ||
| + | This query has two parts | ||
| + | |||
| + | SELECT CourseID FROM StudentsCourses_vw WHERE StudentID = 1 | ||
| + | |||
| + | returns | ||
| + | {| | ||
| + | !CourseID | ||
| + | |- | ||
| + | |9 | ||
| + | |- | ||
| + | |10 | ||
| + | |} | ||
| + | |||
| + | then | ||
| + | |||
| + | <sql> | ||
| + | SELECT CourseID, CourseName, CourseNumber | ||
| + | FROM Course | ||
| + | WHERE | ||
| + | ( | ||
| + | CourseID NOT IN | ||
| + | ( | ||
| + | SELECT CourseID FROM StudentsCourses_vw WHERE StudentID = 1 | ||
| + | ) | ||
| + | ) | ||
| + | </sql> | ||
| + | |||
| + | returns | ||
| + | {| | ||
| + | ! CourseID !! CousreName !!CourseNumber | ||
| + | |- | ||
| + | |11 || Data Design || 36-2601 | ||
| + | |- | ||
| + | |168 || Application Design || 36-4601 | ||
| + | |- | ||
| + | |169 OOP 36-2001 | ||
| + | |} | ||
Course adder example | Course adder example | ||
Revision as of 03:22, 12 April 2007
Contents
Review Data Diagram for final
- are they normal?
- can the design acomplish your goals?
- are they over engineered?
Sql Aggregate Functions
They perform a calculation on a set to values and return a single value. Aggregate functions are determinate. They will return the same value given the same dataset.
- AVG
- MIN
- CHECKSUM
- SUM
- CHECKSUM_AGG
- STDEV
- COUNT
- STDEVP
- COUNT_BIG
- VAR
- GROUPING
- VARP
- MAX
<sql> SELECT MAX(PricePerPound) as MaxPrice from CheesePrice
SELECT AVG(PricePerPound) as AvgPrice from CheesePrice
SELECT COUNT(CheeseID) as Count from CheesePrice </sql>
Sub Query
A query may be a part of another query. This allows
IN vs EXSISTS
Remember the Many to Many relation ship in the Student Registration System
Here a student has many course and a course has many student. Imagine in the registration system the student will be presented with a list of classes that they can add. That list of classes should not include the courses that they are already taking. Course
| CourseID | CourseName | CourseNumber |
|---|---|---|
| 9 | Science | 66-0002 |
| 10 | Math | 66-0001 |
| 11 | Data Design | 36-2601 |
| 168 | Application Design | 36-4601 |
| 169 | OOP | 36-2001 |
Student
| StudentID | PeopleID | OasisID |
|---|---|---|
| 1 | 1 | 666666 |
| 2 | 2 | 777777 |
StudentCourses
| StudentID | CourseID | SemesterID |
|---|---|---|
| 1 | 9 | 1 |
| 2 | 9 | 1 |
| 1 | 10 | 1 |
StudentsCourses_vw <sql> SELECT dbo.Student.PeopleID, dbo.Student.OasisID, dbo.StudentCourses.SemesterID, dbo.Course.CourseName,
dbo.Course.CourseNumber, dbo.Student.StudentID, dbo.Course.CourseID
FROM dbo.StudentCourses INNER JOIN
dbo.Student ON dbo.StudentCourses.StudentID = dbo.Student.StudentID INNER JOIN dbo.Course ON dbo.StudentCourses.CourseID = dbo.Course.CourseID
</sql>
<sql> SELECT CourseID, CourseName, CourseNumber FROM Course WHERE (
CourseID not in
(
SELECT CourseID FROM StudentsCourses_vw WHERE StudentID = @StudentID
)
) </sql>
This query has two parts
SELECT CourseID FROM StudentsCourses_vw WHERE StudentID = 1
returns
| CourseID |
|---|
| 9 |
| 10 |
then
<sql> SELECT CourseID, CourseName, CourseNumber FROM Course WHERE (
CourseID NOT IN
(
SELECT CourseID FROM StudentsCourses_vw WHERE StudentID = 1
)
) </sql>
returns
| CourseID | CousreName | CourseNumber |
|---|---|---|
| 11 | Data Design | 36-2601 |
| 168 | Application Design | 36-4601 |
| 169 OOP 36-2001 |
Course adder example
http://iam.colum.edu/dd/classsource/class8/student.aspx
SQL Subquery
Uploader/Email
Mappath
Server.Mappath
upload permissions
HomeWork
Web Skeleton of your site
Demostate one feature
