Basic Logic, SQL Statements AND/OR You

A quick tour of basic logic and how to evaluate logical expressions and

implement simple SQL queries.

Statement of Truth (Not!)

The statement is the foundational basis for logic. Is the statement TRUE or FALSE?

Cat = Black

Bike = Red

TRUE

FALSE

Statement of Truth (Not!)

Evaluations can also be based on numerical values:

NumCat = 1

NumBike < 1

TRUE

FALSE

We know its value, now what?

Statement can be combined using the following conjunctions:

• AND• OR• NOT• Others…

AND Truth Table

X Y X AND Y

False False

True False

False True

True True

FALSE

FALSE

FALSE

TRUE

OR Truth Table

X Y X OR Y

False False

True False

False True

True True

FALSE

TRUE

TRUE

TRUE

NOT Truth Table

X NOT X

False

True

TRUE

FALSE

Other Truths

• NAND = NOT AND: (Inverts AND result)

• NOR = NOT OR: (Inverts OR result)

• XOR: True if only one operator is true

Conditionals

How to compare to values.

Conditional Statements

• Equal• Not Equal• Greater Than• Less Than• Greater Than or Equal To• Lesser Than or Equal To• Like

=< > “≠”><>= “≥”<= “≤”Like

=< >><>=<=Like

X = 4X < > 9Y > 2X < 1 BazillionX >= 4Y <= 7Z Like “Do%”

Conditional Statements

Set Values:X=4Y=5Z=“Dog”

Examples

Example 1:

(Cat = Black) AND (Bike = Red)

FALSE

Example 2:

(Cat = Yellow) OR (NumBike > 1)

FALSE

Example 3:

(Cat <> Grey) OR (Bike = Green)

TRUE

Example 4:

(NumCat <= 2) AND (Bike = Blue)

TRUE

Example 5:

NOT (Cat Like “Ca%”)

FALSE

Example 6:

NOT ((NumCat < 10) AND (Bike Like “Blu%))OR ((NumCat <= NumDog) OR (Bike = Blue))

TRUE

Basic SQL Statement

Bare Minimums

SELECT fieldname 1, fieldname 2, ...fieldname n

FROM tablename

Adding Conditionals

SELECT fieldname 1, fieldname 2, ...fieldname n

FROM tablenameWHERE (fieldname conditional value)

logic_operand (fieldname conditional value) ...

Adding Sort Values

SELECT fieldname 1, fieldname 2, ...fieldname n

FROM tablenameWHERE (fieldname conditional value)

logic_operand (fieldname conditional value) ...

ORDER BY fieldname

SQL Statement Examples

Generic Report 2

SELECT RequestNumber, ResourceName AS Name, Agency, KindCode AS Kind, Trainee as T, UnitID, CheckinDate, CheckinTime

FROM vBasicRptsWHERE kindcode like 'hc%' or kindcode =

'cc'ORDER BY RequestNumber

Crew Query

SELECT RequestNumber, ResourceName AS Crew

FROM vBasicRpts WHERE Status <> 'D' AND Agency = 'BIA'

and KindCode in ('HC1', 'HC2')

Personnel Count by Agency

SELECT Agency, COUNT(*) AS [Agency Count], SUM(NumberPersonnel) AS NumberPersonnel

FROM vBasicRpts GROUP By Agency

DIVS Checkin

SELECT ResourceName, CheckinDate FROM vBasicRpts

WHERE KindCode = 'DIVS' and CheckinDate between '05/15/07' and '05/20/07'

ORDER BY ResourceName

Just For Grins…

The following query is an example of how to perform a selection statement from multiple tables as well as a method of minimizing the amount of typing needed when specifying those tables.

The query itself is designed to produce a list of records that has Accounting Codes that are set incorrectly. Note: Make sure you understand all components of this query before using on an active database. You must accept all responsibility for it’s use.

Just For Grins…SELECT C.RequestNumber, C.ResourceName, C.AgencyCode,

C.HomeUnit, C.SectionDesc, C.KindCode, C.ActivityDate, C.AccountingCode, C.AccrualCode, B.Status

FROM vCost C ,VBasicRpts BWHERE (C.RequestNumber = B.RequestNumber ) and (B.Status like 'C')

and (C.RequestNumber like 'c%' or C.RequestNumber like 'o%') and not ((C.AccountingCode like 'paxy99' and C.AccrualCode like 'STO') or (C.AgencyCode like 'BIA' and C.AccountingCode like 'xy99') or (C.AgencyCode like 'BLM' and C.AccountingCode like 'xy99') or (C.AgencyCode like 'NPS' and C.AccountingCode like 'xy99') or (C.AgencyCode like 'FWS' and C.AccountingCode like 'xy99')or (C.AgencyCode like 'FS' and C.AccountingCode like 'paxy99')or ((C.AgencyCode like 'PVT' or C.AgencyCode like ‘CA') and

( C.AccountingCode like ‘99999') or (C.AccountingCode like ‘99998')))

ORDER BY AgencyCode

Questions?