Author :Roshan Loyalka.

Company :Torry Harris Business Solutions(www.thbs.com)

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STRUCTURED QUERY LANGUAGE (SQL)

Introduction.
• The Oracle RDBMS is available on many different
operating system platforms including Windows and
UNIX.
• Oracle is a relational DBMS - even the data dictionary is
simply a collection of tables of data along with indexes
and other objects such as sequences and triggers.
• SQL has a basic grammar and syntax.
• The functionally of the SQL language is virtually identical
across these operating system platforms.
• Using SQL does not require programming experience, but
programming experience can help you conceptualize
what a particular SQL command will accomplish.
• The keywords for SQL queries that retrieve data are
SELECT, FROM, WHERE, and ORDER BY. Other
command options also exist, but these are the basic ones.
Connecting to the ORACLE Database.
• Directions for connecting to the ORACLE database are
given in the web handout, Getting Started with Oracle that
is available on the course web site.
Naming Difficulties.
• When building a schema (meaning the definition of the
 tables, indexes, and other objects that comprise a
database), it is important to name objects like tables,
columns, indexes with meaningful names. A failure to
follow this naming rule can result in difficulties for users
when they are creating queries.
• Oracle allows object names to be up to 30 characters
long. Make use of this capability.
• Here are some rules to follow.
• Don't abbreviate unless it is necessary. Example, it

is better to name a column WorkerName than

Wname.
• Be consistent when abbreviating. Don't use EmpNo in
one table and Eno in another table and EmpNumber in still
another table.
• The Purpose or Meaning of a column or table must be
apparent from the name. What would be the meaning of
a table named Scde (Storage Code)? A better name
would be STORAGECODE.
• If you use Underscores as part of a naming convention,
then be consistent. If you are not consistent, then no one
can remember when to use them and when not to use
them.
• Be consistent in using Plurals. Is the name of that table
"EMP" or "EMPS"? Is it "NOTE" or "NOTES"?
 SQL BASIC INFORMATION
SQL and UNIX Syntax.
• The SQL syntax used in these notes complies with
Oracle’s SQL*PLUS product.
• UNIX syntax used in these notes complies with most
UNIX operating systems.
• The American National Standards Institute (ANSI) first
published ANSI SQL standards in 1986.
• Oracle Corporation - provides SQL*PLUS (an enhanced
version of SQL) as part of the Oracle RDBMS product.
This means that SQL*PLUS has some non-ANSI
standard SQL commands that will not run on other
RDBMS platforms.
• Microsoft Corporation - provides the SQL Server RDBMS
software -- a competitor with Oracle Corporation.
SQL Standards - Their Characteristics and Benefits.
• The ANSI SQL Standard provides:
• Specific syntax and semantics of SQL data

definition and datamanipulation languages.

• Basic data structures and operations for designing,
assessing, maintaining, controlling, and protecting an
SQL database.
• Portability of applications and database definition. Easy
to move applications from one machine to another.
• Minimal standards for adoption among products claiming
to be SQL compatible.
• Reduced training costs - IS professionals share a

common language.
• Productivity - IS professionals can become proficient in
 its use.
• Application longevity - A language tends to remain
standard for a long time.
• Reduced dependence on a single vendor.
SQL Data Types.
• Data stored in a relational database can be stored using a
variety of data types. The primary ORACLE data types
are NUMBER, VARCHAR, and CHAR for storing
numbers anda text data; however, there are additional
data types that are supported to support backward
compatability with products.given below:

KEY DATA TYPES

Fixed-length character data, size characters long.
CHAR(size) Maximum size=255; default=1 byte. Padded on right
with blanks to full length of size.
DATE Valid dates range from Jan 1, 4712 B.C. to Dec 31,
4712 A.D.
For NUMBER column with space for 40 digits, plus
space for a decimal point and sign. Numbers may be
expressed in two ways: first, with numbers 0 to 9,
NUMBER the signs + and -, and a decimal point(.); second, in
scientific notation, e.g. 1.85E3 for 1850. Valid values
are 0 and positive and negative numbers from 1.0E-
130 to 9.99…E125.
Variable length character string, maximum size up to
VARCHAR2(size)
2000 bytes.
MISCELLANEOUS
DATA TYPES AND
VARIATIONS
DECIMAL Same as NUMBER.
FLOAT Same as NUMBER.
INTEGER Same as NUMBER.
INTEGER(size) Integer of specified size digits wide; same as
NUMBER(size) of specific size digits wide.
LONG Character data of variable size up to 2Gb in length.
Only one LONG column may be defined per
table. LONG columns may not be used in
subqueries, functions, expressions, where clauses,
or indexes. A table containing LONG data may not
be clustered.
LONG RAW Raw binary data; otherwise the same as LONG
(used for images).
LONG VARCHAR Same as LONG
NUMBER(size) For NUMBER column of specified size in digits.
NUMBER(size,d) For NUMBER column of specified size with d digits
after the decimal point, e.g. NUMBER(5,2) could
contain nothing larger than 999.99 without an error
being generated.
NUMBER(*) Same as NUMBER.
SMALLINT Same as NUMBER.
RAW(size) Raw binary data, size bytes long, maximum
size=255 bytes.
ROWID A value that uniquely identifies a row in an Oracle
database - it is returned by the pseudo-column
ROWID. Table columns may not be assigned this
type.
VARCHAR(size) Same as VARCHAR2. Always use VARCHAR2.

SQL and SQLPLUS Basics and Error Messages.

• We have already seen that SQL can be used to select
data.
• SQL is used for data manipulation in terms of adding,
updating, or deleting data.
• The primary verbs for data manipulation are insert,
update, or delete data.
• Taken together, these are the four primary verbs you use
in SQL.
 • We will start learning to write SQL commands by
connecting through a telnet session to connect to the
ORACLE database, and then by using the SQLPLUS
command to enter the SQLPLUS environment.
• Start using SQLPLUS by typing the command at the
prompt SQLPLUS (or by using the appropriate graphical
user interface if it is provided). The typical prompt you
receive is: SQL >
• Sometimes your connection will fail and you will receive
an error message.
• If you get the following errors, it may be that access

to the ORACLE binary files is not available because

the PATH command for your account is incorrectly
established - see your instructor to correct this.
• The problem could also be that the database has been
shutdown and so ORACLE is not running.
• ERROR: ORA-1017: invalid username/password; logon
denied. Unable to CONNECT to ORACLE after 3
attempts, exiting SQL*Plus
• When you are finished with your work, you quit SQLPLUS
with the QUIT or EXIT command.
Case in Names and Data.
• Oracle ignores case (upper versus lower case letters)
when you type table and column names. It converts table
and column names to uppercase when you type a query
and checks the query's validity in the data dictionary.
Data, however, may be stored as a combination of upper
and lower case. You can use Oracle functions to convert
data between upper and lower case if that becomes
necessary as part of a programming application.
• Case matters only if SQLPLUS is checking a value for
 equality in the database. For example, the following
conditions are not identical.
• Where Section = 'f'

• Where Section = 'F'

• Here the values "f" and "F" inside quotes are called
literals, meaning literal values.

SELECT QUERIES
SQL Query Suntax.
• This section teaches you to write a number of different
types of SQL queries.
• SQL is based on the data transform language first named
SEQUEL.
• This is a relational calculus type of language which
provides three capabilities in a very simple syntax.
• The basic syntax as we have already seen is:
SELECT (column list)
FROM (table list)
WHERE (condition clause)

A Sample Query.
• This result comes from the ORACLE database which is in
use at SIUE. This database contains all tables given in
the Oracle Press: The Complete Reference, but you do
not need to have this book in order to use this set of
notes.
SQL> Select City, Temperature, Humidity from
WEATHER
2 where Temperature > 80 and Humidity <
90
3 order by Temperature ;
CITY TEMPERATURE HUMIDITY
----------- ----------- ----------
PARIS 81 62
ATHENS 97 89

Describing a Table.
• Often it is useful to be able to describe the structure of a
table because you may not be familiar with a particular
table.
• The Describe command is used to accomplish this. This
example gives the description of the WEATHER and
LOCATION tables in the ORACLE database.

SQL> describe weather;

Name Null? Type
--------------- -------- ----
CITY VARCHAR2(11)
TEMPERATURE NUMBER
HUMIDITY NUMBER
CONDITION VARCHAR2(9)
SQL> describe location;
Name Null? Type
--------------- -------- ----
CITY VARCHAR2(25)
COUNTRY VARCHAR2(25)
CONTINENT VARCHAR2(25)
LATITUDE NUMBER
NORTHSOUTH CHAR(1)
LONGITUDE NUMBER
EASTWEST CHAR(1)

Result of a SELECT Command.

• The SELECT command produces a "virtual table" -- this
is a combination of columns and rows from one or more
selected tables given in the query. This normally
produces a subset of the columns and rows that comprise
the tables in the query.
• The virtual table produced by a query is stored on disk in
a Temporary tablespace area or in RAM that is
sometimes called a "scratch" space because it is used
over and over. The actual location of the virtual table is a
function of the size of the table.
• When the virtual table is no longer needed, Oracle
disposes of it.
• The basic operation of each of the three components of
the SELECT command are explained below.

SELECT List the columns including expressions involving

columns from base tables or views to be projected into
the table that will be the result of the command.
FROM Identifies the tables or views from which columns will
be chosen to appear in the result table. This must also
list the tables or views needed to join tables to process
the query.
WHERE Includes conditions that restrict the rows selected as
well as the conditions for joining two or more tables or
views.

THE COMMUNITY HOSPITAL

EXAMPLE DATABASE

• The table examples given below assume the database

schema represented by the ER diagram given here. The
ER diagram only shows primary key attributes.

BILLED
BILL_NO NUMBER(5) - PRI KEY
PATIENT_NO NUMBER(9)
ITEM_CODE NUMBER(5)
CHARGE NUMBER(7,2)
TREATS
PHY_ID NUMBER(4) - PRI KEY
PATIENT_NO NUMBER(4) - PRI KEY
PROCEDURE_NO NUMBER(4) - PRI KEY
DATE_TREATED DATE - PRI KEY
TREAT_RESULT VARCHAR2(50)
ITEM
ITEM_CODE NUMBER(4) - PRI KEY
DESCRIPTION VARCHAR2(50)
NORMAL_CHARGE NUMBER(7,2)
PHYSICIANS
PHY_ID NUMBER(4) - PRI KEY
PHY_PHONE CHAR(8)
PHY_NAME VARCHAR2(50)
PATIENT
PATIENT_NO NUMBER(4) - PRI KEY
DATE_LAST_TREATED DATE
PAT_NAME VARCHAR2(50)
ROOM_LOCATION CHAR(4)
ROOM
ROOM_LOCATION CHAR(4) - PRI KEY
ROOM_ACCOMODATION CHAR(2)
ROOM_EXTENSION NUMBER(4)
PROCEDURES
PROCEDURE_NO NUMBER(4) - PRI KEY
PROC_DESCRIPTION VARCHAR2(50)

EXAMPLE #1 – SIMPLE SELECT TO RETURN A SET OF

ROWS BASED ON A SIMPLE SINGLE VALUE IN THE
WHERE CLAUSE.
• Consider the table named BILLED as defined above. The
command to select the PATIENT_NO, ITEM_CODE, and
CHARGE and from the BILLED table for a specific
PATIENT_NO is:
SELECT patient_no, item_code, charge
FROM billed
WHERE patient_no = 1117;
PATIENT_NO ITEM_CODE CHARGE
---------- ---------- ----------
1117 2222 7.54
1117 2255 25

• Notice the SELECT clause always ends in the semi-

colon.
EXAMPLE #2 – ELIMINATE DUPLICATE ROWS.
• To eliminate duplicate rows in order to display just distinct
rows, the SELECT DISTINCT command may be used.
This gives all of the different charges that are stored to
the table.
SELECT DISTINCT charge
FROM billed;
CHARGE
----------
2.21
4.56
6.68
7.54
 7.75
25
...not all rows are displayed here.

EXAMPLE #3 – SIMPLEST QUERY DISPLAYS ALL

COLUMNS IN A TABLE.
• To display all columns from the BILLED table use the
wildcard *.
SELECT *
FROM billed
WHERE patient_no = 1116;
PATIENT_NO ITEM_CODE CHARGE
---------- ---------- ----------
1116 2242 4.56
1116 2243 6.68

EXAMPLE #4 – QUERY DISPLAYS ALL COLUMNS AND

ROWS.
• To display all columns and all rows from the BILLED table
eliminate the WHERE clause.
SELECT *
FROM billed ;
PATIENT_NO ITEM_CODE CHARGE
---------- ---------- ----------
1117 2222 7.54
1113 2233 2.21
1117 2255 25
1113 2222 7.75
1115 2245 175
...not all rows are displayed here.

ARITHMETIC, LOGICAL, AND OTHER OPERATORS.

• The various arithmetic, logical, and additional operators
are shown in the table below.
• Examples using some of the operators are provided after
the table.
• Arithmetic operators are used to qualify expressions in
WHERE clauses.
• There are operators such as LIKE for performing
character string pattern matching.
• The IS NULL and IS NOT NULL operators are used to
see if data exists in a row - a column that is completely
empty is NULL. The word IS is required.
• The logical operators AND, OR, and NOT may be used to
create complicated WHERE clauses. You may use
parentheses to group logical operators properly.
ARITHMETIC OPERATORS
Page = 6 Page is equal to 6
Page > 6 Page is greater than 6
Page >= 6 Page is greater than or equal to 6
Page < 6 Page is less than 6
Page <= 6 Page is less than or equal to 6
Page != 6 or Page ^= 6 Page is not equal to 6

or Page <> 6

USING THE LIKE OPERATOR

Feature LIKE ‘Mo%’ Feature begins with the letters Mo. Note the %
wildcard represents any number of spaces or
characters.
Feature LIKE ‘_ _I%’ Feature has the letter I in the third position. Note
the underline (_) represents one space.

USING THE IS NULL and IS NOT NULL OPERATORS

Precipitation IS NULL The column named Precipitation contains no
value or is unknown.
Precipitation IS NOT NULL The column named Precipitation contains some
value or is known.

USING THE IN and BETWEEN OPERATORS

Page IN (1,2,3)Page is in the
list (1,2,3)
Page BETWEEN 6 AND 10 Page is equal to 6, 10, or anything in between.
Section IN (‘A’, ‘B’, ‘F’) Section is in the list (A, B, or F ) Note use of ‘’
quotes.

USING LOGICAL OPERATORS – OR, AND, NOT

Section = ‘A’ OR Section = The value of the column Section is either A or B
‘B’ for this to evaluate to TRUE.
Section = ‘A’ AND Page > 2 The value of the column Section must be A and
the value of the column Page must be greater
than 2 for this to evaluate to TRUE.
NOT Section = ‘A’ Section must have some value other than A for
this to evaluate to TRUE.

EXAMPLE #5 – USES LOGICAL AND OPERATOR.

• To display all charges greater than $5.00 for the
PATIENT_NO 1116.
SELECT charge
FROM billed
WHERE patient_no = 1116 AND charge > 5.00;
CHARGE
----------
6.68

EXAMPLE #6 – USES LOGICAL OR OPERATOR.

• To display all charges for either patient 1116 or patient
1117.
SELECT patient_no, charge
FROM billed
WHERE patient_no = 1116 OR patient_no = 1117;
PATIENT_NO CHARGE
---------- ----------
1117 7.54
1117 25
1116 4.56
1116 6.68
1117 167.67
1117 222.21
1117 4.92

EXAMPLE #7 – USES COUNT FUNCTION.

• SQL provides many built-in functions (such as COUNT,
MAX, MIN, SUM, and AVG) to be used as operators for
columns.
• An example of counting the number of times patient 1116
has been charged for items. This counts the number of
rows for the patient.
SELECT COUNT(*)
FROM billed
WHERE patient_no = 1116;
COUNT(*)
---------
2

EXAMPLE #8 – DISPLAYS DISTINCT ROWS –

ELIMINATES DUPLICATE ROWS ON THE OUTPUT.
• Suppose you want the number of DISTINCT procedures
performed on a patient. This counts the number of distinct
values that appear in the column named
PROCEDURE_NO for the patient.
SELECT COUNT ( DISTINCT procedure_no )
FROM treats
WHERE patient_no = 1113;
COUNT(DISTINCTPROCEDURE_NO)
---------------------------
2

EXAMPLE #9 – SPECIFY MEANINGFUL COLUMN NAMES.

• To "jazz up" the output, you may specify creative column
names to appear at the top of a column of output.
• The default is to list the column name above the column.
SELECT COUNT (DISTINCT procedure_no) AS "No.
of Procedures"
FROM treats
WHERE patient_no = 1113;
No. of Procedures
-----------------
2

DISPLAYING CONSTANTS AND CALCULATED VALUES

• Before using data aggregate functions such as COUNT or
SUM, you should understand that you cannot mix row-
level data output in the same SELECT clause with data
aggregate functions.
EXAMPLE #10.
• To display a calculated value such as the current charge
and the amount that would be charged if the charge were
increased by 6% for all rows in the ITEM table, the
command is:
SELECT normal_charge, normal_charge*1.06
FROM item;
NORMAL_CHARGE NORMAL_CHARGE*1.06
------------- ------------------
7.54 7.9924
2.21 2.3426
4.5 4.77
284.59 301.6654
25 26.5
...not all items are listed here.

EXAMPLE #11.
• To compute how long a patient was in the hospital, you
can perform arithmetic operations on both numeric as well
as date type data.
• The example below shows the use of date type data to list
 all patients hospitalized more than 6 days. This also
shows an example of using an arithmetic expression in a
WHERE clause.
SELECT patient_no, date_discharged,
date_admitted,
(date_discharged - date_admitted + 1)
As "No. of Days In"
FROM patient
WHERE (date_discharged - date_admitted + 1 ) >
6;
PATIENT_NO DATE_DISC DATE_ADMI No. of Days In
---------- --------- --------- --------------
1117 22-DEC-01 16-DEC-01 7
1114 24-DEC-01 15-DEC-01 10
1115 25-DEC-01 15-DEC-01 11

SORTING, GROUPING and the BETWEEN OPERATOR

EXAMPLE #12 – USING SORTING AND GROUPING.
• The ORDER BY optional clause will sort results in either
ascending or descending order. The optional clause for
descending is DESC.
• The GROUP BY optional clause is used to group rows
with common values.
• The example below produces a list of the total charges
per patient for expensive medical items (CHARGE greater
than $100 for an item) where patients owe the hospital a
sum (total charges over $500).
• Also note that we can only include column data such as
the PATIENT_NO and aggregate data such as
 SUM(CHARGE) together in a query when we use the
GROUP BY clause.
• The BETWEEN operator is used to simplify query writing
for a range of qualifications, for example, when a value is
BETWEEN x and y, using the BETWEEN x and y is
equivalent to saying the value is >=x AND =<y.
SELECT patient_no, SUM(charge)
FROM billed
WHERE (patient_no BETWEEN 1110 AND 1200) AND
charge > 100
GROUP BY patient_no
HAVING SUM(charge) > 200
ORDER BY patient_no;
PATIENT_NO SUM(CHARGE)
---------- -----------
1112 782.55
1117 389.88

• The GROUP BY specifies control breaks for subtotals.

• The HAVING clause must be used because the group-
level data is aggregated.
• The HAVING clause is like WHERE but must be used
when the condition involves group-level data.

EXAMPLE #13 – MAJOR AND MINOR SORTS.

• You can sort by more than one variable (major and minor
sort).
• The query below shows the results in descending total
charge sequence (use of the DESC option since the
default is ascending), then by ascending PATIENT_NO
 as the minor sort variable.
SELECT patient_no, SUM(charge) total_charge
FROM billed
WHERE (patient_no BETWEEN 1110 AND 1200) AND
charge > 100
GROUP BY patient_no
HAVING SUM(charge) > 50
ORDER BY total_charge DESC, patient_no;
PATIENT_NO TOTAL_CHARGE
---------- ------------
1112 782.55
1117 389.88
1115 175

EXAMPLE #14 – ANOTHER BETWEEN EXAMPLE.

• This is another example of the BETWEEN operator and
lists all patients who were charged between $160 and
$170 for item 2245.
• The second query shows all charges for item 2245.
SELECT patient_no, charge
FROM billed
WHERE item_code = 2245 AND
charge BETWEEN 160 AND 170;
PATIENT_NO CHARGE
---------- ----------
1112 167.67
1112 167.67
1117 167.67
SELECT patient_no, charge
FROM billed
WHERE item_code = 2245;
PATIENT_NO CHARGE
---------- ----------
1115 175
1112 167.67
1112 167.67
1117 167.67

THE IN OPERATOR
• The IN operator may be used to replace the OR operator
to simplify a query.
• Later you will see examples where IN must be used for
complex queries.

EXAMPLE #15 – USING THE IN OPERATOR.

• This example lists the patients who had either Dr.
Hawkeye Pierce or Dr. Trapper John or Dr. Jonas
Salkman as a physician.
SELECT DISTINCT patient_no, phy_id
FROM treats
WHERE phy_id IN
(8887, 8886, 8882);
PATIENT_NO PHY_ID
---------- ----------
1112 8887
1113 8882
1113 8887
1115 8886
 1116 8886
1117 8887

• It would be nice to show the patient names (PAT_NAME

field) and associated physician names (PHY_NAME field)
along with the Patient information. We shall see how to
accomplish this in the next section.
MULTIPLE TABLE QUERIES
• SQL can produce data from several related tables by
performing either a physical or virtual join of the tables.
The default is a virtual join.
• The WHERE clause is most often used to perform the
JOIN function where two or more tables have common
columns such as is the case for the PATIENT and
BILLED tables.
EQUI-JOIN and NATURAL JOIN
• The Equi-Join and Natural Join are equivalent except
that duplicate columns are eliminated in the Natural Join
that would otherwise appear in the Equi-Join.
• Recall the immediate example above where the query
listed the PATIENT_NO and PHY_ID, but not the
PAT_NAME or PHY_NAME fields. This query joints the
PATIENT, PHYSICIAN, and TREATS tables to produce
the desired information.
• The query also demonstrates the use of an ALIAS for a
table name - here we have three aliases (PA, PH, and
TR), one for each table.
• When two or more tables have a column with the same
name, the name can be qualified by using the table
 name combined with the period (.) in referring to the
column, e.g. billed.patient_no. Note that columns with
unique names do not have to be qualified by the table
name.
• The COLUMN commands given prior to the SELECT are
used to format the output.
EXAMPLE #16a – JOIN THREE TABLES.
COLUMN pat_name FORMAT A18;
COLUMN phy_name FORMAT A18;
SELECT DISTINCT PA.patient_no, pat_name,
PH.phy_id, phy_name
FROM patient PA, physician PH, treats TR
WHERE PA.patient_no = TR.patient_no AND
PH.phy_id = TR.phy_id AND
PH.phy_id IN (8887, 8886, 8882);
PATIENT_NO PAT_NAME PHY_ID PHY_NAME
---------- ------------------ ------
------------------
1112 Eminem 8887 Dr. Hawkeye
Pierce
1113 George Marshall 8882 Dr. Jonas
Salkman
1113 George Marshall 8887 Dr. Hawkeye
Pierce
1115 Barbara Streisand 8886 Dr. Trapper
John
1116 G. W. Bush 8886 Dr. Trapper
John
1117 Sally Field 8887 Dr. Hawkeye
Pierce
 • The next example below shows the PATIENT_NO and
DATE_DISCHARGED from the PATIENT table and the
associated CHARGE from the BILLED table.
• The sequence of table names in the FROM list is
immaterial. If a column is indexed, the DBMS will
automatically optimize the use of the index in parsing the
query.
EXAMPLE #16b – JOIN TWO TABLES.
SELECT billed.patient_no, date_discharged,
charge
FROM billed, patient
WHERE patient.patient_no = billed.patient_no;
PATIENT_NO DATE_DISC CHARGE
---------- --------- ----------
1117 22-DEC-01 7.54
1113 21-DEC-01 2.21
1117 22-DEC-01 25
1113 21-DEC-01 7.75
1115 25-DEC-01 175
1116 22-DEC-01 4.56
...not all of the rows are shown here.

OUTER JOIN and TABLE NAME ALIASES

(ABBREVIATIONS)
• There may be situations where a row in one table, such
as a PATIENT table has no corresponding rows in
another table such as the CHARGE table (the patient has
not yet incurred any charges - a most unusual
circumstance in any hospital).
 • The JOIN of these tables will produce rows where some
columns have NULL values. This is called the Outer
Join. The Oracle RDBMS supports Outer Joins.
EXAMPLE #17 – OUTER JOIN and USING ALIAS.
• The following command might produce the sample table
shown after the command.
• This example also shows another example of using "alias"
names for tables in order to shorten the query that is
written.
• Here the alias for BILLED has been shortened to the
letter "B" and PATIENT to "P".
• Note the resulting NULL cells for some rows.
• The (+) for the table for which there will be NULL values
in terms of matching the P.PATIENT_NO to the
B.PATIENT_NO is required.
SELECT p.patient_no, b.charge
FROM billed b, patient p
WHERE p.patient_no = b.patient_no(+);
PATIENT_NO CHARGE
---------- ----------
1111
1112 225
1112 167.67
1112 167.67
1112 4.92
1112 222.21
1113 2.21
1113 7.75
1114
1115 175
 1116 4.56
...not all rows are shown here.

• If we only want a list of patients who have no charges yet,

the following query with a WHERE clause testing for
NULL values will work. Note that this result is a subset of
the above result.
SELECT p.patient_no, b.charge
FROM billed b, patient p
WHERE p.patient_no = b.patient_no(+) AND
b.charge IS NULL;
PATIENT_NO CHARGE
---------- ----------
1111
1114

SUBQUERIES
• The object of a WHERE clause can be another SELECT
query.
• Sometimes this makes it simpler to write a query that
would otherwise have a very complex WHERE clause.
• The two queries shown in the example below are
equivalent. Both queries produce a list of ITEM_CODEs
and the associated description of the items for a specific
patient. To produce the list the ITEM and BILLED tables
must be joined.
EXAMPLE #18 – A COMPLEX QUERY AND THE
SUBQUERY.
SELECT item.item_code, description
FROM item, billed
WHERE item.item_code = billed.item_code AND
patient_no = 1116;
ITEM_CODE DESCRIPTION
---------- ----------------
2242 4 inch dressing
2243 Syringe, 8 gauge

SELECT item_code, description

FROM item
WHERE item_code IN
(SELECT item_code FROM billed
WHERE patient_no = 1116);
ITEM_CODE DESCRIPTION
--------- ----------------
2242 4 inch dressing
2243 Syringe, 8 gauge

EXAMPLE #19 – USING IN WITH THE SUBQUERY.

• When an inner query (subquery) returns a set or list of
values, we can use the IN operator to match on equality
conditions.
• In fact, the IN operator was used for the above as shown
here.
SELECT item_code, description
FROM item
WHERE item_code IN
 (SELECT item_code FROM billed
WHERE patient_no = 1116);

• There are many other types of subqueries. You can

spend many weeks studying the topic of SQL query
writing.

VIEW DEFINITION
• A VIEW is a virtual table that does not exist in reality, but
is a logical definition of a set of related columns,
usually from multiple tables.
• A VIEW presents data to the end user of an application
system the way that the end user is used to seeing the
data.
• For example, the Customer Order Form is a view of

data from several different tables including

CUSTOMER, ORDERS, PRODUCT, ORDERLINE,
and SALESPERSON.
• A VIEW can also be used to simplify query generation
and to add data security to a database by limiting the data
that an end user can access.
• A VIEW definition is permanently stored as part of the
database.
• The example below creates a view named
PATIENT_BILL that includes the PATIENT_NO,
ITEM_CODE and CHARGE columns from the BILLED
table and the DESCRIPTION column from the ITEM table,
and the DATE_DISCHARGED from the PATIENT table.
EXAMPLE #20 – CREATE A VIEW.
CREATE VIEW patient_bill AS
 SELECT B.patient_no, P.pat_name,
B.item_code, charge,
description, date_discharged
FROM patient P, billed B, item I
WHERE P.patient_no = B.patient_no AND
I.item_code = B.item_code;
View created.

• Note that the relationship from PATIENT to BILLED is

1:N and the relationship from ITEM to BILLED is 1:N.
• In other words, the BILLED table is the intersection table
linking PATIENT and ITEM.
• Now you can query the view PATIENT_BILL just as you
would a table. When you execute the query, the view is
generated by the DBMS and loaded with data, then your
query is executed.
Column Description Format A22;
SELECT patient_no, item_code, charge,
description
FROM patient_bill
WHERE patient_no = 1117;
PATIENT_NO ITEM_CODE CHARGE DESCRIPTION
---------- --------- --------
---------------------
1117 2222 7.54 Syringe, 19 gauge
1117 2255 25 Saline Soln, 1
liter
1117 2245 167.67 Surgical Prep Pack
#8
1117 2224 222.21 Surgical Prep Pack
#4
1117 2267 4.92 Bed Pan

DERIVED COLUMNS
• A view may contain derived (or virtual) columns.
• For example, the total charges by patient for room and
special items in a room (item codes between 2200 and
2250).
• A view for this aggregate data can be created from the
PATIENT_BILL view that was created in the example
above.
• The new view (code shown below for this view of a view)
named ROOM_CHARGE has two virtual columns named
OCCUPANT and ROOM_CHGS.
• Note that ROOM_CHARGES is the sum of the charges
for an occupant of the room.

EXAMPLE #21 – DERIVED COLUMNS.

CREATE VIEW room_charge (occupant, room_chgs)
AS
SELECT pat_name, sum(CHARGE)
FROM patient_bill
WHERE item_code BETWEEN 2200 AND 2250
GROUP BY pat_name;

EXAMPLE #21 – SELECTING FROM A VIEW.

• Now you can select charges for an occupant with the
simple query given below.
Column occupant Format A20;
SELECT occupant, room_chgs
FROM room_charge
WHERE room_chgs > 100;
OCCUPANT ROOM_CHGS
-------------------- ----------
Barbara Streisand 175
Eminem 782.55
Sally Field 397.42

which is equivalent to:

SELECT pat_name, SUM(charge)
FROM patient_bill
WHERE item_code BETWEEN 2200 AND 2250
GROUP BY pat_name
HAVING SUM(charge) > 100;
PAT_NAME SUM(charge)
-------------------- -----------
Barbara Streisand 175
Eminem 782.55
Sally Field 397.42

Attached here is the Script file used to create and

populate the tables used in this handout. They files
assume the existence of the DATA tablespace and the
DATA_INDEX tablespace for storage of tables and indexes.
The user account assumed is named DBOCK. If you run the
script to create the tables with data in your own Oracle
account, replace the name of the user account with your own
account name. Do not attempt to create the PUBLIC SYNONYMS
since these already exist for the DBOCK account.
REM Table ROOM
drop table ROOM;
create table ROOM (
ROOM_LOCATION char(4)
constraint PK_ROOM primary key
using index tablespace DATA_INDEX
pctfree 5,
ROOM_ACCOMMODATION char(2)
constraint NN_ACCOMMODATION NOT NULL,
ROOM_EXTENSION number(4) default NULL
)
tablespace DATA;

Insert into ROOM values ('GM01', 'P2', 1111);

Insert into ROOM values ('GM02', 'P2', 1112);
Insert into ROOM values ('GM03', 'P2', 1113);
Insert into ROOM values ('GM04', 'P2', 1114);
Insert into ROOM values ('IC01', 'P1', 2221);
Insert into ROOM values ('IC02', 'P1', 2222);
Insert into ROOM values ('IC03', 'P1', 2223);

REM Table PATIENT

drop table PATIENT;
create table PATIENT (
PATIENT_NO number(4)
constraint PK_PATIENT primary key
using index tablespace DATA_INDEX
pctfree 5,
DATE_ADMITTED date default sysdate
constraint NN_DATE_ADMITTED NOT NULL,
DATE_DISCHARGED date default NULL,
PAT_NAME varchar2(50)
constraint NN_PAT_NAME NOT NULL,
ROOM_LOCATION char(4)
constraint NN_ROOM_LOCATION NOT NULL,
constraint FK_PATIENT_ROOM foreign key
(ROOM_LOCATION)
references ROOM
on delete cascade
)
tablespace DATA;

Insert into PATIENT values (1111, '15-DEC-01', '20-DEC-01',

'Tom Thumb', 'GM03');
Insert into PATIENT values (1117, '16-DEC-01', '22-DEC-01',
'Sally Field', 'GM01');
Insert into PATIENT values (1113, '17-DEC-01', '21-DEC-01',
'George Marshall', 'GM03');
Insert into PATIENT values (1114, '15-DEC-01', '24-DEC-01',
'William Clinton', 'GM02');
Insert into PATIENT values (1116, '18-DEC-01', '22-DEC-01',
'G. W. Bush', 'IC01');
Insert into PATIENT values (1115, '15-DEC-01', '25-DEC-01',
'Barbara Streisand', 'IC03');
Insert into PATIENT values (1112, '18-DEC-01', '20-DEC-01',
'Eminem', 'GM01');

REM Table ITEM

drop table ITEM;
create table ITEM (
ITEM_CODE number(4)
constraint PK_ITEM primary key
using index tablespace DATA_INDEX
pctfree 5,
DESCRIIPTION varchar2(50) default NULL,
NORMAL_CHARGE number(7,2)
)
tablespace DATA;

Insert into ITEM values (2222, 'Syringe, 19 gauge', 7.54);

Insert into ITEM values (2233, '9 inch gauze', 2.21);
Insert into ITEM values (2244, 'Tylenol 800MG', 4.50);
Insert into ITEM values (2223, 'Morphine Drip, 0.2 liter',
284.59);
Insert into ITEM values (2255, 'Saline Soln, 1 liter',
25.00);
Insert into ITEM values (2243, 'Syringe, 8 gauge', 6.68);
Insert into ITEM values (2267, 'Bed Pan', 4.92);
Insert into ITEM values (2266, 'Surgical Prep Pack #2',
195.95);
Insert into ITEM values (2265, '4 inch gauze', 1.19);
Insert into ITEM values (2245, 'Surgical Prep Pack #8',
167.67);
Insert into ITEM values (2268, 'Bandaid, 3 inch', 0.76);
Insert into ITEM values (2242, '4 inch dressing', 4.56);
Insert into ITEM values (2224, 'Surgical Prep Pack #4',
222.21);

REM Table PHYSICIAN

drop table PHYSICIAN;
create table PHYSICIAN (
PHY_ID number(4)
constraint PK_PHYSICIAN primary key
using index tablespace DATA_INDEX
pctfree 5,
PHY_PHONE char(8) default NULL,
PHY_NAME varchar2(50)
constraint NN_PHY_NAME NOT NULL
)
tablespace DATA;

Insert into PHYSICIAN values (8880, '888-0001', 'Dr. Oprah

Heart');
Insert into PHYSICIAN values (8887, '888-0007', 'Dr.
Hawkeye Pierce');
Insert into PHYSICIAN values (8882, '888-0002', 'Dr. Jonas
Salkman');
Insert into PHYSICIAN values (8884, '888-0004', 'Dr.
Winifred Winfield');
Insert into PHYSICIAN values (8886, '888-0006', 'Dr.
Trapper John');

REM Table PROCEDURES

drop table PROCEDURES;
create table PROCEDURES (
PROCEDURE_NO number(4)
constraint PK_PROCEDURES primary key
using index tablespace DATA_INDEX
pctfree 5,
PROC_DESCRIPTION varchar2(50)
)
tablespace DATA;

Insert into PROCEDURES values (3225, 'Appendectomy');

Insert into PROCEDURES values (3233, 'Lobotomy');
Insert into PROCEDURES values (3234, 'Thoracic Procedure');
Insert into PROCEDURES values (3232, 'Cervical Disk');
Insert into PROCEDURES values (3230, 'Hip Replacement');
Insert into PROCEDURES values (3231, 'Arthroscopic
Procedure');
Insert into PROCEDURES values (3237, 'Ingrown Toenail');

REM Table TREATS

drop table TREATS;
create table TREATS (
PHY_ID number(4),
PATIENT_NO number(4),
PROCEDURE_NO number(5),
DATE_TREATED date,
TREAT_RESULT varchar2(50) default NULL,
constraint FK_TREATS_PATIENT foreign key
(PATIENT_NO)
references PATIENT
on delete cascade,
constraint FK_TREATS_PHYSICIAN foreign key (PHY_ID)
references PHYSICIAN
on delete cascade,
constraint FK_TREATS_PROCEDURES foreign key
(PROCEDURE_NO)
references PROCEDURES
on delete cascade,
constraint PK_TREATS
primary key (PHY_ID, PATIENT_NO, PROCEDURE_NO,
DATE_TREATED)
using index tablespace DATA_INDEX
pctfree 5
)
tablespace DATA;

Insert into TREATS values (8887, 1117, 3232, '17-DEC-

01','Repaired Disk OK');
Insert into TREATS values (8882, 1113, 3230, '18-DEC-
01','Repaired Right Hip OK');
Insert into TREATS values (8887, 1113, 3232, '17-DEC-
01','Repaired Disk OK');
Insert into TREATS values (8884, 1114, 3233, '15-DEC-
01','Brain Partially Removed');
Insert into TREATS values (8886, 1116, 3234, '19-DEC-
01','Removed Left Lung');
Insert into TREATS values (8880, 1111, 3237, '15-DEC-
01','Removed toenail');
Insert into TREATS values (8886, 1115, 3230, '17-DEC-
01','Repaired Left Hip OK');
Insert into TREATS values (8887, 1112, 3231, '18-DEC-
01','Repaired Left Knee OK');
Insert into TREATS values (8887, 1112, 3231, '19-DEC-
01','Repaired Right Knee OK');

REM Table BILLED

drop table BILLED;
create table BILLED (
BILL_NO number(5),
PATIENT_NO number(4),
ITEM_CODE number(5),
CHARGE number(7,2),
constraint FK_BILLED_PATIENT foreign key
(PATIENT_NO)
references PATIENT
on delete cascade,
constraint FK_BILLED_ITEM foreign key (ITEM_CODE)
references ITEM
on delete cascade,
constraint PK_BILLED
primary key (BILL_NO)
using index tablespace DATA_INDEX
pctfree 5
)
tablespace DATA;

Insert into BILLED values (00001, 1117, 2222, 7.54);

Insert into BILLED values (00002, 1113, 2233, 2.21);
Insert into BILLED values (00003, 1117, 2255, 25.00);
Insert into BILLED values (00004, 1113, 2222, 7.75);
Insert into BILLED values (00005, 1115, 2245, 175.00);
Insert into BILLED values (00006, 1116, 2242, 4.56);
Insert into BILLED values (00007, 1112, 2224, 225.00);
Insert into BILLED values (00008, 1112, 2245, 167.67);
Insert into BILLED values (00009, 1116, 2243, 6.68);
Insert into BILLED values (00010, 1112, 2245, 167.67);
Insert into BILLED values (00011, 1112, 2224, 222.21);
Insert into BILLED values (00012, 1112, 2267, 4.92);
Insert into BILLED values (00013, 1117, 2245, 167.67);
Insert into BILLED values (00014, 1117, 2224, 222.21);
Insert into BILLED values (00015, 1117, 2267, 4.92);
REM End of Database Table and Data Insertion Code
REM Now create the public synonyms to allow easy access
REM by students to the tables.

drop public synonym BILLED;

create public synonym BILLED for DBOCK.BILLED;
drop public synonym ROOM;
create public synonym ROOM for DBOCK.ROOM;
drop public synonym PATIENT;
create public synonym PATIENT for DBOCK.PATIENT;
drop public synonym ITEM;
create public synonym ITEM for DBOCK.ITEM;
drop public synonym TREATS;
create public synonym TREATS for DBOCK.TREATS;
drop public synonym PHYSICIAN ;
create public synonym PHYSICIAN for DBOCK.PHYSICIAN;
drop public synonym PROCEDURES;
create public synonym PROCEDURES for DBOCK.PROCEDURES;

REM End of Script

END OF NOTES
for any suggestions mail me...

mail:roshan_loyalka2005@rediff.com