lec 3

Question 1

table level of an sql search

Answer 1

get all data in a table

ex. Select * from Employees

Question 2

record level of an sql search

Answer 2

get a particular record from a table

select * from Employees where EmployeeNO = 977

Question 3

slice and dice

Answer 3

get selected records from a table
get selected attributes for all records from a table
get selected attributes from all records from a table

Question 4

Problems with Select *

Answer 4

gives all attributes in whatever order their stored internally
- might not be order your expecting
- might include attributes your not expecting
If someone adds that attribute you would also get that attribute

Question 5

Format of a query

Answer 5

SELECT (DETERMINES OUTPUT)
FROM (LIST OF TABLES(source of data))
WHERE (CONDITIONS (determine records selected))
- results in a table

Question 6

Renaming headings

Answer 6

add AS to each attribute in select clause

ex. SELECT XXXX AS XXX

Question 7

In Modifying results….

Answer 7

You should be able to use any properly formed expression that evaluates to a single value as one of the attributes in a select

Question 8

Some SQL operations

Answer 8

determines the first position, if any, at which one string, S1, occurs within another, S2.
returns the length of a given character string.

(truncate)

Question 9

Data typing in a select

Answer 9

is based on the most appropriate data type available for the individual attribute

• data type of an individual attribute is based on its data definition
• data type of a computed value is established implicitly based on the data types involved in the computation

Question 10

implicit type conversions can occur in

Answer 10

expressions, fetch operations, single row select operations, inserts, deletes and updates

Question 11

CAST operator

Answer 11

SPECIFIES EXPLICIT TYPE CONVERSIONS

- allows you to change between reals and integers when presenting data

Question 12

Sorting results

Answer 12

Add order by

Add Desc for reverse order

Question 13

summarizing results

Answer 13

use distinct and correct

• distinct will give you a short listing of which types are in there (getting a set of different values of an attribute)
• adding distinct forces sql processor to add unique rows

Question 14

Group by clause

Answer 14

creates a seperate group for each distinct value of some attribute

Question 15

having clause

Answer 15

restricts members in a group based on some conditions