Midterm in EWEB1

                                                Reporting Aggregated Data

                         Using the Group Functions

Lesson 4

·          I learned in this lesson how to group data from the lowest to the highest.

·         And I also know the 7 group function.

Ø  AVG

Ø  COUNT

Ø  MAX

Ø  MIN

Ø  STDDEV

Ø  SUM

Ø  VARIANCE

I learned also that:

 ü  Where clause cannot use the to restrict the instead of where you can use having clause to restrict the groups.

ü  You can use GROUP BY clause to divide rows in a table to a smaller groups.

ü  You can also use GROUP BY in multiple columns.

Displaying Data

from Multiple TablesDisplaying Data

from Multiple Tables

LESSON 5

            Lesson 5 is all about JOINS I learn in this lesson how to join table from another table using:

                         • Equijoins

                         • Nonequijoins

                         • Outer joins

                         • Self-joins

                         • Cross joins

                         • Natural joins

                          • Full (or two-sided) outer joins

Equijoins - is adding two tables with the same name.

Using - is use to match only one column when more than one column matches.

Self-join - if the two tables have the same output. Like the manager_id from employees and the employee_id from manager table you can use Self-join.

In this lesson I also know how to use Aliases.

·         Aliases is use to simplify queries.

·         You can use any characters for your queries.

·         And it also use to improve our performance

Using Subqueries to Solve Queries

Lesson 6

           

            In this lesson I learned that:

ü  What is subqueries.

ü  A subquery is a SELECT statement that is embedded in clause of another SQL Statement.

ü  I already know how to write single row and multiple row Subqueries

And I learned that this operator is use for single row comparison:

                                       1. = equal to

                                       2. > greater than

                                       3. >= greater than or equal to

                                       4. <= less than or equal to

                                       5. <> not equal

And I also learned the uses of multiple-row comparison operator:

                              1. IN  -  Equal in any member in the list

                              2. ANY  -  Compare value to each value returned by the 

                                                subquery

                              3. ALL  -  Compare value to every value returned by the 

                                                subquery