SQL

CIS4365: Professor Kirs Slide Number: 1

SQL

Chapter 9:An Introduction to Structured

Query Language (SQL)(With Considerable Modifications)


SQL

Why SQL?? “De facto standard in RDBMS” Can be implemented on all platforms Processes data on a SET Level

Works with groups of data (Tables) Relatively Few Statements

Portability Ease of Learning Ease of use

Developed around concept of Data Definition Language (DDL) Data Manipulation Language (DML) Data Control Language (DCL)


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Database Definition Recall our Physician Table:

PhysID

Name

Specialty

Street

City

State

ZipCode

Physician Table Attributes/Fields

We know the fields we need, and perhaps even what field names we will use, BUT what type of data will we use to store the information ???

What Types of data are there ???


SQLDatabase DefinitionBasic Data Types: (C Data Types used for illustration)Character char/signed 1-byte -128 to + 127

unsigned char 1-byte 0 to + 255

Integer int/signed 2-bytes -32,768 to 32,767

unsigned int 2-bytes 0 to 65,537

long/signed 4-bytes -2,147,483,648 to 2,147,483,647

unsigned long 4-bytes 0 to 4,294,967,295

Real float 4-bytes 7 decs. precisiondouble 8-bytes 10 decs. precisionlong double 16-bytes 10 decs. precision

(Maybe)(OR) int/signed 4-bytes -2,147,483,648 to 2,147,483,647

(Maybe)(OR) char/signed 2-byte -32,768 to 32,767

(Maybe)(OR) unsigned char 2-bytes 0 to 65,537

(Maybe)(OR) unsigned int 4-bytes 0 to 4,294,967,295

(OR) long/signed 8-bytes -9,223,372,036,854,780,000 to …….

(OR) unsigned long 4-bytes 0 to 18,467,440,737,906,000,000


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Database DefinitionOf course, there are additional abstract data structures

Arrays A fixed number of contiguous data elements all of the same type

Strings An array of data type char

Structs A combination of two or more data types• Structured data objects• Records

Others • Date/Time• Graphics• OLE (Object Linking and Embedding)• Hyperlinks


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Database DefinitionOracle Allows for the following Basic data types to be entered into Fields (There are others)

CHAR • A string

Characters

• The length (N) MUST be specified• If less than N characters are entered, N

spaces will STILL be allocated

• Up to 255 characters are allowed• Usage: Fieldname CHAR(N)


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Database Definition

VARCHAR • A string

Characters

• The length (N) MUST be specified• ONLY the number characters are entered

will be allocated space

• Up to 255 characters are allowed• Usage: fieldname VARCHAR(N)

VARCHAR2, LONG VARCHAR


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Database DefinitionNumeric Data Types

INTEGER Typically, up to 10 - 11 digits are allowed• Range (Typically):

-2,147,483,648 through +2,147,483,647

SMALLINT Typically, up to 4 - 5 digits are allowed• Range (Typically):

-32,768 through +32,767

• Usage: fieldname INTEGER

• Usage: fieldname SMALLINT


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Database DefinitionNumeric Data Types

DECIMAL(m,n)

A Real (Floating-Point) Number with m total digits (INCLUDING the sign and decimal point) and n decimals to the right of the decimal point• m may (Typically) be as large as 19

• Usage: fieldname DECIMAL(10,4)

• n may (Typically) be as large as 7 - 8

This allows for a number between99999.9999 through -9999.999 (The sign counts)

But ONLY to 3 decimal point of precision


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Database DefinitionDate and Time Data Types

DATE Date Value• (Typically) Displayed as mm/dd/yy• Usage: fieldname DATE

TIME Time Value• (Typically) Displayed as hh:mm:ss• Useful in Time Stamping• Usage: fieldname TIME


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Database Definition NOW, Returning to our Physician Table:

PhysID

Name

Specialty

Street

City

State

ZipCode


Let’s assume the following Field Names and Data types:

physid CHAR(9)physname CHAR(30)specialty CHAR(15)street CHAR(20)city CHAR(20)

state CHAR(2)

zip CHAR(5)


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Before going on to SQL, Let’s see how other languages might create the record

Database Definition

01 PHYSICIAN05 PHYSID PIC X(9).05 PHYSNAME PIC X(30).05 SPECIALTY PIC X(15).05 STREET PIC X(20).05 CITY PIC X(20).05 STATE PIC X(2).05 ZIP PIC X(5).

In COBOL:


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Database Definition

In Pascal:

type physician = recordphysid: array[1..9] of char;physname: array[1..30] of char;specialty: array[1..15] of char;street: array[1..20] of char;city: array[1..20] of char; state: array[1..2] of char;zip: array[1..5] of char;

end;

In C:struct physician{ char physid[10]; char physname[31]; char specialty[16]; char street[21]; char city[21];

char state[3];char zip[6];

};


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Database Definition The SQL Commands Needed to create the table are

PhysID

Name

Specialty

Street

City

State

ZipCode

Physician Table Attributes/Fields CREATE TABLE physician

( physid CHAR(9), physname CHAR(30), specialty CHAR(15), street CHAR(20), city CHAR(20), state CHAR(2), zip CHAR(5) );

Every SQL Command ends with a semicolon


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Database Definition Let’s Examine the command

CREATE TABLE physician( physid CHAR(9), physname CHAR(30), specialty CHAR(15), street CHAR(20), city CHAR(20), state CHAR(2), zip CHAR(5) );

• We have CREATEd a new table (file) called physician

• Each record we enter will contain 7 fields

• Each record will require 9 + 30 + 15 + 20 + 20 + 2 + 5 = 101 Bytes of Storage

• We encased our field declarations between parentheses ()

• Each field (except for the last) was separated by a comma ( , )


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Database DefinitionBut don’t we know more about the table?? Yes, We Know:

• The Table physician has as its primary key the field physid

• It wouldn’t make sense to leave the physname field blank (although theoretically, we could)

We Could also make some assumptions:• The physician lives in Texas (Code: TX)


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Database Definition Let’s rewrite the command:

Adding these Qualifiers will assure that the fields will NOT be left empty

CREATE TABLE physician( physid CHAR(9) NOT NULL, physname

CHAR(30) NOT NULL,

PhysID

Name

Specialty

Street

City

State

ZipCode


This is Superfluous. WHY ???


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PhysID

Name

Specialty

Street

City

State

ZipCode


( physid CHAR(9) NOT NULL, physname

CHAR(30) NOT NULL,specialty CHAR(15), street CHAR(20), city CHAR(20), state CHAR(2), DEFAULT ‘TX’,

If nothing is entered into the state field, TX will be entered by default


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PhysID

Name

Specialty

Street

City

State

ZipCode


( physid CHAR(9) NOT NULL, physname

CHAR(30) NOT NULL,specialty CHAR(15), street CHAR(20), city CHAR(20), state CHAR(2), DEFAULT ‘TX’,

zip CHAR(5), PRIMARY KEY (physid) );

physid has been identified as the primary key


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Database Definition We Can get also add additional constraints

CREATE TABLE physician( physid CHAR(9) NOT NULL, physname CHAR(30) NOT NULL, specialty CHAR(15) NOT NULL, street CHAR(20), city CHAR(20), state CHAR(2), DEFAULT ‘TX’, zip CHAR(5), PRIMARY KEY (physid) UNIQUE (specialty) );

• Let’s assume that we can only have one (1) specialist in each area:


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Database Definition We need to ‘Back-Track’

The Network Schema

The Network Subschema

The conceptual Organization of the entire database

The conceptual Organization of the database as “seen” by the applications programs accessing it

• Remember that we previously discussed Schemas

We need to Develop our tables with this in mind


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Database Definition A Schema consists of

• Tables (which we previously created)• Views (Or Virtual Table)

A subset of rows and columns Not a physical entity (as are tables) Can be treated as tables

• User Authorization

Created by the DBMS each time they are referenced by the user as a query

Usernames allowed (and how allowed) to access the tables


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Database Definition A more appropriate CREATE might have been:

CREATE SCHEMAATHORIZATION pkirs

CREATE TABLE physician( physid CHAR(9),

physname CHAR(30) NOT NULL, specialty CHAR(15) NOT NULL, street CHAR(20), city CHAR(20), state CHAR(2), DEFAULT ‘TX’, zip CHAR(5), PRIMARY KEY (physid) UNIQUE (specialty) );


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Database Definition Some Basic CREATE TABLE Guidelines

• Choose Numeric data types ONLY if calculations are to be performed on the field

• Make the lengths of the character columns long enough to accommodate future values (Remember the Y2K Problem)

• Apply the same guidelines for DECIMAL data• Don’t automatically choose VARCHAR over CHAR• Use EXACTLY the same data types for columns which

will be compared often or used in calculations together • Use NOT NULL when a column MUST contain a value• PRIMARY KEYS ARE ALWAYS NOT NULL


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Database Definition Let’s Consider the relationship between our

Physician and Patient tables

Physician PatientTreats

Remember what this means:• A Patient MUST have one (and ONLY one)

Physician• A Physician MAY have more than 1 (one)

Patient


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Database Definition We Previously defined our Patient fields:

Patient Table Attributes/Fields

PatID

Name

Address

PhysID

And how Patient relates to our Physician table:

PhysID

Name

Specialty

Street

City

State

ZipCode


physid has in Patient is a foreign key


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Database Definition We now need to define our Patient fields:

Patient Table Attributes/Fields

PatID

Name

……..

PhysID

Let’s Pretend that field Address doesn’t Exist

CREATE TABLE patient( patid CHAR(9) NOT NULL, nameCHAR(30) NOT NULL,physid CHAR(9) NOT NULL, PRIMARY KEY (patid) FOREIGN KEY (physid)

REFERENCES physician (physid));

We have established our relationship between patient and physician


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Database Definition Again, Let’s Examine the command

• We have CREATEd a new table (file) called patient

• Each record we enter will contain 3 fields

• Each record will require 9 + 30 + 9 = 48 Bytes of Storage

• We encased our field declarations between parentheses ()

• Each field (except for the last) was separated by a comma ( , )

CREATE TABLE patient( patid CHAR(9) NOT NULL, name CHAR(30) NOT NULL,

physid CHAR(9) NOT NULL, PRIMARY KEY (patid), FOREIGN KEY (physid)

REFERENCES physician (physid) );

• We have linked two (2) tables together


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Database Definition We are on the way to building a Script (Program)

• A text file that contains SQL commands So far, our Script would appear as:


CREATE TABLE physician( physid CHAR(9) NOT NULL,

physname CHAR(30)NOT NULL,

specialty CHAR(15) NOT NULL, street CHAR(20), city CHAR(20), state CHAR(2), DEFAULT ‘TX’, zip CHAR(5), PRIMARY KEY (physid) UNIQUE (specialty) );



CREATE TABLE patient( patid CHAR(9) NOT NULL, name CHAR(30) NOT NULL,


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Database Definition

Patient IllnessSuffer

Finally, Let’s create two more tables

Remember, this is a Many-to-Many Relationship

M1

M

1Patient Table

PatID

Name

……..

PhysID

IllCode

Name

Others

Illness TableSuffers Table

Date/Time

Others

PatID

IllCode


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Database Definition First, let’s create our illness table:

Let’s Pretend that field Others doesn’t Exist

CREATE TABLE illness( illcode CHAR(10), name CHAR(20) NOT NULL,

PRIMARY KEY (illcode) UNIQUE (name) );

IllCode

Name

. . . . . .

Illness Table


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Database Definition We now need to define our Suffers fields:

Let’s Pretend that field Others doesn’t Exist

CREATE TABLE suffers( patid CHAR(9) NOT NULL, illcodeCHAR(10) NOT NULL,sdate DATE NOT NULL, stime TIME NOT NULL, PRIMARY KEY (patid, illcode), FOREIGN KEY patid

REFERENCES patient (patid), FOREIGN KEY illcode

REFERENCES illness (illcode) );

Suffers Table

Date/Time

. . . . . . .

PatID

IllCode


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Database Definition Our Script would appear as:


CREATE TABLE physician( physid CHAR(9) NOT NULL,

physname CHAR(30) NOT NULL, specialty CHAR(15) NOT NULL, street CHAR(20), city CHAR(20), state CHAR(2), DEFAULT ‘TX’, zip CHAR(5), PRIMARY KEY (physid) UNIQUE (specialty) );



CREATE TABLE patient( patid CHAR(9) NOT NULL,

name CHAR(30) NOT NULL,

CREATE TABLE illness( illcode CHAR(10) NOT NULL, name CHAR(20)NOT NULL,PRIMARY KEY (illcode) UNIQUE (name) );CREATE TABLE suffers( patid CHAR(9),

illcode CHAR(10) NOT NULL, sdate DATE NOT NULL, stime TIME NOT NULL, PRIMARY KEY (patid, illcode), FOREIGN KEY (patid)

REFERENCES patient (patid), FOREIGN KEY (illcode)

REFERENCES illness (illcode) );


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Database Definition Additional options in CREATE

CHECK• Suppose ALL of our physicians could ONLY live in

Arlington, Dallas, or Fort Worth• Our physician table could be rewritten as:

CREATE TABLE physician( physid CHAR(9) ,

physname CHAR(30) NOT NULL,specialty CHAR(15),

street CHAR(20), city CHAR(20), state CHAR(2), DEFAULT ‘TX’,

zip CHAR(5), PRIMARY KEY (physid), CHECK (city in ‘Arlington’, ‘Dallas’, Ft. Worth’) );


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Database Definition Additional CHECK options

• If we had an integer field called salary, and salary HAD to be greater than 50000:

CREATE SCHEMA( ººººº CHECK (salary > 50000) );

• If we had an integer field called salary, and salary HAD to be greater than 50000 BUT less than 100000:

CREATE SCHEMA( ºººººCHECK (salary BETWEEN 50000 AND 100000) );


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Database Definition Security/Privilege Options

• The owner (AUTHORIZATION pkirs) has full access

• If we wished to allow user clinton (which MUST be a registered username) full access to table physician:

CREATE SCHEMAATHORIZATION pkirsCREATE TABLE physician( ººººº )GRANT ALL ON physician TO clinton;


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Database Definition• If we wished to allow user clinton to insert new records into

to table physician:

GRANT INSERT ON physicianTO clinton;

• If we wished to allow user clinton ONLY to edit tables physician and patient:

GRANT UPDATE ON physician, patient TO clinton;

• If we allow user clinton ONLY to view physician and patient data:

GRANT SELECT ON physician, patient TO clinton;

• If we allow everyone to view and update table physician:

GRANT SELECT, UPDATE ON physician TO PUBLIC


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Database Modification Inserting records

INSERT INTO physician VALUES (‘123456789’, ‘Smith, John’, ‘Surgery’, ‘123Main’, ‘El Paso’, ‘TX’, ‘76019’)

• Note that this corresponds to our physician table structure:

( physid CHAR(9), physname CHAR(30), specialty CHAR(15), street CHAR(20), city CHAR(20), state CHAR(2), zip CHAR(5) );


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Database Modification

• Any new records added (or changes made to records) will not be permanent until we enter the command:

Saving records

COMMIT;

Changing our minds

• If we decide we shouldn’t have entered the record (or made the changes), we can enter the command:

ROLLBACK;

• Which will restore the database back to how it was before the last COMMIT was entered


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Database Modification Updating Records

• Right now, our physician table appears as:

123456789 Smith, John Surgery 123 Main El Paso TX 76019

physid physname specialty street city state zip

• If we wished to change John Smith’s specialty from surgery to OB/GYN we would enter the command:

UPDATE physician SET specialty = ‘OB/GYN’WHERE physid = ‘123456789’;

• NOTE: The changes would be applied only AFTER we COMMIT


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Database Modification Updating Records

• Notice also that the command

UPDATE physician SET specialty = ‘OB/GYN’WHERE physid = ‘123456789’;

• Requires us to find for a specific record using the search condition:

WHERE physid = ‘123456789’;

(a TRUE/FALSE condition)


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Database Modification Deleting Records

• To delete a record from a database, we must once again find it and issue the command:

DELETE FROM physician WHERE physid = ‘123456789’;

• Once Again, The changes would be applied only AFTER we COMMIT


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Database Modification Deleting Records

• We could also delete multiple records:

DELETE FROM patient WHERE physid NOT IN (‘123456789’, ‘234567890’);

• This would delete all records who did not have these two physicians as their primary providers

(We can get much fancier here)


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Database Modification Deleting Tables

• To delete a table from a database, we need only issue the command:

DROP TABLE physician;

• A DROP DOES NOT require an explicit COMMIT statement (although a ROLLBACK will undo the command)


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Database Structure Modification Altering the database (FOR MOST RDBMS)

• Unrestricted Alterations• Adding a new column to a table• Deleting a primary key

(Foreign Key references are automatically removed)• Deleting a foreign key

• Restricted Alterations

• Changing a columns data type, size, and default value is allowed ONLY if there are NO DATA in the column being modified


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Database Structure Modification Altering the database (FOR MOST RDBMS)

• Restricted Alterations• Adding a Primary Key, BUT only if there are no

duplicate values• Adding UNIQUE and CHECK condition ONLY if

the field matches the added condition • Adding a foreign key allowed ONLY if the values are

NOT NULL or exist in the referenced Table • Changing a column name is Not Allowed

(Continued)

• Deleting a column is NOT allowed


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Database Structure Modification Altering the database

• To add a field to a database

ALTER TABLE physician ADD (malpracticefees DECIMAL(7,2));

• We can also specify WHERE to add it and add constraints:

ALTER TABLE physician ADD (malpracticefees DECIMAL(8,2))BEFORE streetINIT = 10000.00;


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• Suppose that we find out that we need more space for our specialty field, presently:

ALTER TABLE physician, MODIFY (specialty CHAR(20));

• which would accept up to 20 characters for a physician specialty

• We might enter the command:

specialty CHAR(15),


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• If, for some reason, we decided to change physid from a character to a numeric field, we might enter the command:

ALTER TABLE physician MODIFY (physid INTEGER);

• NOTE: This assumes that the field CAN be converted into a numeric Field

• If physid contained the data: 4B7876D

It could not be converted


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• To remove a primary or foreign key, we might issue the command:

DROP CONSTRAINT ……. ;

• NOTE: If this sounds like a cop-out, it is because there are a number of variations


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• IF we have designated a primary of foreign key (or we have removed them as above), we could now add them as:

ALTER TABLE physician ADD PRIMARY KEY (physname);

• AND

ALTER TABLE patient ADD FOREIGN KEY (physname)REFERENCES (physician);


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Importing Data from another Database

NOTE:

• Data imported from other tables MUST be of the same data type

• IF we had a table physinfo which was IDENTICAL to our table physician, we could enter the command:

INSERT INTO physician SELECT *

FROM physinfo;


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Importing Data from another Database• IF the table physinfo had some fields which matched

our table physician (and some which perhaps didn’t), we might enter the command:

INSERT INTO physician, (street, city, state, zip) SELECT (streetname, cityname, statename, zipcode)

FROM physinfoWHERE NOT (physid = idnum);

• NOTE: Fields in table physician had which were NOT imported from table physinfo will remain empty.


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Database Queries Extracting information from a database Performed using high-level Query Languages Very similar across SQL platforms

(Although differences DO exist) Use of standard English commands:

• SELECT *

• FROM• WHERE

• SELECT

• GROUP BY• HAVING• ORDER BY


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Would result in the (approximate) display:

physid physname specialty street city state zip------------- --------------------- ------------- ------------- -------- ------- --------123456789 Smith, John OB/GYN 123 Main El Paso TX 76019

Database Queries The Command:

SELECT * FROM physinfo ;

The Command:SELECT physid, physname, specialty FROM physician;

physid physname specialty ------------- -------------------- ---------------123456789 Smith, John OB/GYN



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Database Queries In SQL, We also have the choice of listing ALL (using

SELECT *, OR SELECT ALL) records or DISTINCT records:SELECT DISTINCT specialty FROM physician;

Might result in the (approximate) display:

specialty-------------SurgeryDermatologyOB/GYNOpthamologyENTPediatrics


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SELECT physid, physname FROM physician WHERE (specialty = ‘Surgery’ OR specialty = ‘Dermatology’);


physid physname------------- -------------------- 123456789 Smith, John 234567890 Jones, Mary345678901 Houston, Sam456789012 Bush, G.W.567890123 Clinton, Hillary

NOTE: Because we are using the OR operator, ALL records meeting the condition will be shown


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SELECT physid, physname FROM physician WHERE (specialty = ‘Surgery’ AND specialty = ‘Dermatology’);


physid physname------------- -------------------- NOTE: With the AND

operator, ONLY those records meeting BOTH conditions will be shown (in this case, None)


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Database Queries SQL has the following built-in Operators:

Operator(s) Description* / Multiplication Division+ - Addition Subtraction

Suppose we had a table called inventory:

100 2.56 3.89 45

partnum cost price onhand

101 0.89 1.45 122102 1.76 2.99 82103 12.83 17.99 8104 4.88 7.22 28105 7.16 12.99 53


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Database Queries Suppose we wanted to find the items where our

profit margin was 60% or more

In this case our profit is defined as:price

cost - 1

For our table inventory, our profit margins are:

100 2.56 3.89 45

partnum cost price onhand

101 0.89 1.45 122102 1.76 2.99 82103 12.83 17.99 8104 4.88 7.22 28105 7.16 12.99 53

* 100

Margin51.9562.9269.8940.2247.9581.42


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Database Queries

SELECT partnum, price - cost FROM inventory WHERE ((price / cost - 1) * 100 => 0.60);

The Command:


partnum price - cost------------- --------------- 101 1.33 102 1.23105 5.83

Notice we didn’t do a very good job labeling our fields


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Database Queries

SELECT partnum AS ‘Part’, cost AS ‘Cost’, price AS ‘Price’,price - cost AS ‘Profit’, (price / cost - 1) * 100 AS ‘Margin’

FROM inventory WHERE ((price / cost - 1) * 100 => 0.60) ORDER BY ((price / cost - 1) * 100) DESC;

The Command:


Part Cost Price Profit Margin------ -------- ------- --------- ----------105 7.19 12.99 5.83 81.42102 1.76 2.99 1.23 69.89101 0.89 1.45 1.33 62.95


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Database Queries

SQL has a number of built-in numeric functions:

Function OutputCOUNT The number of rows containing the attributeMIN The minimum attribute encounteredMAX The maximum attribute encounteredSUM The total of all values for a selected attributeAVG The arithmetic mean for a selected attribute


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Database Queries

SELECT COUNT (DISTINCT partnum) AS ‘No. Parts’, MIN (price) AS ‘Cheapest’, MAX(price) AS ‘Costliest’,SUM (cost * onhand) AS ‘Inv. Cost’, SUM (price * onhand) AS ‘Inv. Potential’, AVG ((price / cost - 1) * 100) AS ‘Ave. Margin’,SUM ((price * onhand) - (cost * onhand)) AS ‘Pot. Profit’,

FROM inventory;

The Command:


No. Parts Cheapest Costliest Inv. Cost Inv. Potential Ave. Margin Pot. Profit ------------ ------------ ----------- ------------ ------------------ ----------------- ------------- 6 1.45 17.99 986.86 1631.68 59.06 644.82


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Database Queries SQL also has a number of built-in special

functions:Function OutputBETWEEN Used to define Range LimitsIS NULL Used to check if an attribute contains

NULL ValuesLIKE Used to check similar Character

StringsIN Used to check if an attribute is

contained IN a set of ValuesEXISTS Used to check if an attribute value

exists (The opposite of IS NULL)


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Database Queries

SELECT partnum, cost, priceFROM inventoryWHERE

partnum BETWEEN 102 AND 104;

The Command:


partnum cost price------------- ---------- ---------102 1.76 2.99 103 12.83 17.99104 4.88 7.22


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Database Queries

SELECT physid, physnameFROM physicianWHERE physname LIKE ‘Smi%’;

The Command:


Physid physname------------- -------------123456789 Smithers 234567890 Smith456789012 Smickman678901234 Smiley

Where: % is a wildcard


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Database Queries The LIKE command can take on a few forms:

Search String Pattern MatchedSm% Finds Any string starting with Sm%Sm% Finds Any string containing Sm %Sm Finds Any string ending with SmS_m Finds any 3 letter string beginning

with S and ending in m%S_m% Finds any string containing the letter S

followed by any character, followed by the character m

NOT LIKE The opposite of LIKE


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Database Queries Often, it is necessary to JOIN tables together on

common keys (E.g., a foreign key) We Might enter the command:

SELECT physid, physname, patid, nameFROM physician, patientWHERE physician.physid = patient.physid;

This might result in the (approximate) display:Physid physname patid name------------- ------------- ------------- --------------123456789 Smith 987654321 Gore 123456789 Smith 876543210 Bradley456789012 Jones 765432109 Richardson678901234 Bush 654321098 Sanders

NOTE: If two tables have the same field names, we need to indicate which is which using DOT NOTATION


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Database Queries We can also JOIN multiple tables together Remember our expanded relationship:

Physician PatientTreats Treatment Illness

Prescription Where we had a ternary

relationship between patient, illness, and prescription


In Tabular Form, this appeared as:

Patient Table

PatID

Name

Address

PhysID

Illness Table

Treatment Table

Prescription Table

IllCode

Name

Others

DrugCode

Others

Others

PatID

DrugCode

IllCode

Date/Time

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Database Queries


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Database Queries One command we might enter is:

SELECT physname, patient.name, illness.name, prescription.drugcode

FROM physician, patient, treatment, illness, prescriptionWHERE physician.physid = patient.physidAND patient.patid = treatment.patidAND treatment.illcode = illness.illcodeAND treatment.drugcode = prescription.drugcodeORDER BY physname;

(It CAN get involved)


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Database Queries This command might yield the outcome:

physname patient.name illness.name prescription.drugcode------------- ----------------- ---------------- -----------------------------Bush Iman Beauty S228C99 Clinton Lewinski Sore throat L001H98Clinton Flowers Humiliation J897T11 Guilianni Clinton Humiliation A345B23Jones Richardson Depression J897T11Jones Vonnegut Writersblk K980F66Smith Gore Dullness A345B23 Smith Bradley Tallness S228C99Smith Beethoven Deafness A345B23Smith Aikman Sore Arm A345B23Smith Bradley Tallness A345B23Smith Gore Euphoria S228C99 Smith Astaire Brk Leg A345B23


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Database Queries

The head administrator wants a list of all of Dr. Smith’s patients, their illnesses, and what prescriptions were given to those people.

NOWNOW, remember our original Concern:

Let’s assume that we had a field in our prescription table called drugname (for the name of the drug).

Our command might be:SELECT physname, patient.name, illness.name,

prescription.drugnameFROM physician, patient, treatment, illness, prescriptionWHERE physician.physid = patient.physidAND patient.patid = treatment.patidAND treatment.illcode = illness.illcodeAND treatment.drugcode = prescription.drugcodeAND physid = ‘123456789’;


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physname patient.name illness.name prescription.drugname------------- ----------------- ---------------- ------------------------------Smith Gore Dullness Thorazine Smith Bradley Tallness AspirinSmith Beethoven Deafness ThorazineSmith Aikman Sore Arm Thorazine Smith Bradley Tallness ThorazineSmith Gore Euphoria Aspirin Smith Astaire Brk Leg Thorazine

And Maybe the Administrator DOESDOES have a valid concern


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Database Queries If we wanted to get fancier, we might issue the

command:

SELECT physname, patient.name, illness.name, prescription.drugname

FROM physician, patient, treatment, illness, prescriptionWHERE physician.physid = patient.physidAND patient.patid = treatment.patidAND treatment.illcode = illness.illcodeAND treatment.drugcode = prescription.drugcodeAND physid = ‘123456789’ORDER BY COUNT (prescription.drugname, patient.name);


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physname patient.name illness.name prescription.drugname------------- ----------------- ---------------- ------------------------------Smith Aikman Sore Arm Thorazine Smith Astaire Brk Leg Thorazine Smith Beethoven Deafness Thorazine Smith Bradley Tallness ThorazineSmith Gore Dullness Thorazine Smith Bradley Tallness AspirinSmith Gore Euphoria Aspirin


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Database Queries Notice that our queries can become complex, and that

reentering the command each time becomes tedious

We can create permanent VIEWS• A VIEW is a logical table (NOT physical) which

contains a query

• A VIEW holds the query commands and is run each time it is called

• A VIEW must be CREATEd and selected when to be run


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Database Queries To create our view:

CREATE VIEW drugs_given ASSELECT physname, patient.name, illness.name,

prescription.drugcodeFROM physician, patient, treatment, illness, prescriptionWHERE physician.physid = patient.physidAND patient.patid = treatment.patidAND treatment.illcode = illness.illcodeAND treatment.drugcode = prescription.drugcodeORDER BY physname;


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Database Queries To run our view:

SELECT *FROM drugs_given WHERE physid = ‘123456789’ORDER BY COUNT (prescription.drugname), patient.name;

physname patient.name illness.name prescription.drugname------------- ----------------- ---------------- ------------------------------Smith Aikman Sore Arm Thorazine Smith Astaire Brk Leg Thorazine Smith Beethoven Deafness Thorazine Smith Bradley Tallness ThorazineSmith Gore Dullness Thorazine Smith Bradley Tallness AspirinSmith Gore Euphoria Aspirin

This might again result in the (approximate) display:


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Documents

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