Info 2102 l4 basic select statement lab1

International Islamic University Malaysia
Department of Information Systems
Kulliyyah of Information & Communication Technology
LECTURE 4:
BASIC SELECT
STATEMENTS
Dr. Mira Kartiwi

Capabilities of SQL SELECT Statements
Kuliyyah of ICT – Department of Information Systems
 Selection (Restriction) – Allows for the retrieval
of rows that satisfy certain specified condition
(predicate).
 Projection – Allows for the retrieval of specified
columns (attributes).
 Joining – Allows for the linking of data in
different tables.

More About SELECT
 SELECT is technically a Data Manipulation
Language (DML). However, Oracle does not
classify it as such.
 You can write SELECT statements on multiple
lines. However, you are not allowed to split or
abbreviate keywords.
 SELECT statements are not case sensitive.

More About SELECT
 Clauses are usually placed on separate
lines.
 Indents are used to enhance readability.

Basic SELECT Statement
 SELECT *| { [DISTINCT] column | expression
[alias],...}
FROM table;
 SELECT identifies what column
 FROM identifies which table

Selecting All Columns
SELECT *
FROM doctor;

Selecting Specific Columns
SELECT doc_name, area
FROM doctor;

Using Arithmetic Operations
SELECT doc_name, (annual_bonus+ 500)
FROM doctor;
 Four arithmetic operations according to precedence:
(*, /), (+, -)
 Operators of the same priority are evaluated from left to
right.
 Parentheses are used to force prioritized evaluation and
to clarify statements.

Operator Precedence and
Parantheses
SELECT doc_name, annual_bonus,
10*annual_bonus+500
FROM doctor;
SELECT doc_name, annual_bonus,
10*(annual_bonus+500)
FROM doctor;
 --What is the difference????

NULL Values
 How many doctor has Null value in the
result???
Why??
 Arithmetic expressions containing a null value
evaluate to null

Column Alias
 Renames a column heading.
 Useful with calculations.
 Immediately follows the column name – there can also
be the optional AS keyword between column name and
alias.
 Requires double quotation marks if it contains spaces or
special characters or is case sensitive.

Column Alias
 SELECT doc_name AS name, annual_bonus
FROM doctor
 SELECT doc_name AS “Name”, annual_bonus AS
“Bonus”
FROM doctor
 SELECT doc_name, annual_bonus AS “Bonus
Upgrade”
FROM doctor

Concatenation Operator
SELECT doc_name||area AS “Doctor”
FROM doctor;
 Concatenates columns or character strings to
other columns.
 Is represented by two vertical bars (||).
 Creates a resultant column that is a character
expression.

Literal Character String
SELECT doc_name || ' is from ' || area AS “DOCTOR”
FROM doctor;
 A literal is a character, a number, or a date included in
the SELECT statement.
 Date and character literal values must be enclosed
within single quotation marks.
 Each character string is output once for each row
returned.

Eliminating Duplicate Rows
SELECT DISTINCT area
FROM doctor;
-- how many area??????

Limiting the Rows Selected
SELECT *| { [DISTINCT] column | expression
[alias],...}
FROM table
WHERE condition(s);

The Where Clause
 The WHERE clause can be added to the
SELECT statement to restrict the results to
rows that satisfy a specified condition.
 Rows that do not meet the condition will not be
included in the results.

Comparisons
 The two expressions must be of the same type
 Character string literals should be enclosed in
single quotes
 Date literals should be of the form 'DD-MON-
YY'
 Numeric literals should consist of digits and
optionally, a decimal and/or sign (no commas
or dollar signs)

Comparison Conditions
 Equal (=)
 Greater than (>)
 Greater than or equal to (>=)
 Less than (<)
 Less than or equal to (<=)
 Not equal to (<>, !=, ^=)

WHERE Clause
SELECT doc_name
FROM doctor
WHERE chgperappt >= 40;
 --What does it means?????
 -- how many doctor name James?????
 -- What area is Stevenson?????

Other Comparison Conditions
 Between two values (inclusive) –
BETWEEN... AND...
 IN (set)
 LIKE
 IS NULL
 IS NOT NULL

BETWEEN Condition
 Several special operators serve as shortcuts
for longer expressions.
One is the BETWEEN operator.
 It is used to determine whether or not a value
lies within a specific range (including the end
points)
 General syntax:Expression1 BETWEEN Expression2 AND
Expression 3

BETWEEN Condition
SELECT doc_name, annual_bonus
FROM doctor
WHERE annual_bonus BETWEEN 2000 AND
4000;
-- how many people?

The IN Operator
 Used to see if a value occurs in a set of
possible values
 The set of possible values is specified
within parentheses with commas between
values

IN Condition
SELECT doc_id, doc_name, area
FROM doctor
WHERE doc_id IN (100,356, 558);
-- what area are they in???????

The IS NULL Operator
 Any comparison to a null value that uses the
standard comparison operators will not yield a
match.
 If a check for null values is needed, the IS
NULL operator must be used.

The IS NULL Operator
 Display the IDs of doctors that do not receive
annual bonuses.
SELECT doc_id
FROM doctor
WHERE annual_bonus IS NULL;
--What is the name?---

The LIKE Operator
 Used in conjunction with wildcard characters
to match character string patterns
 % is used to match zero or more characters
 _ is used to match a single character
 Wildcards cannot be used without the LIKE
operator
 The LIKE operator should not be used without
wildcards

LIKE Condition
SELECT *
FROM doctor
WHERE doc_name LIKE 'J%';
-- change to lowercase j
Note:
– Represents any sequence of zero or more characters
(%)
– Represents a single character (_)

The LIKE Operator
Display the full name and phone number for
customers whose phone number begins with 549-67
SELECT pt_lname || ', ' || pt_fname "FULL NAME"
FROM patient
WHERE ptdob LIKE ’13-MAY-__' ;

Logical Operators
 3 standard logical operators (AND, OR, and
NOT) are used to combine expressions
 AND will return a value of true only if both expressions
are true
 OR will return a value of true if either or both of the
expressions are true
 NOT will return the opposite value of the expression.
 Order of precedence: NOT, AND, OR

Other NOT Operators
 The NOT operator can also be used in
conjunction with the special operators as
follows:
 NOT BETWEEN
 NOT IN
 IS NOT NULL
 NOT LIKE

NULL and NOT NULL Conditions
 SELECT docid, docname, annual_bonus
FROM doctor
WHERE annual_bonus IS NULL;
TO NEGATE ..
 SELECT docid, docname, annual_bonus
FROM doctor
WHERE annual_bonus IS NOT NULL;

Lab Assignment 1
 Run the hospital script and create a question
in English as well as its SQL query that
generates:
 NULL values
 Values not within a specific range
 List of names that started from or ended with
specific letter

Info 2102 l4 basic select statement lab1

Recommended

Recommended

More Related Content

What's hot

What's hot (13)

Viewers also liked

Viewers also liked (9)

Similar to Info 2102 l4 basic select statement lab1

Similar to Info 2102 l4 basic select statement lab1 (20)

More from IIUM

More from IIUM (20)

Recently uploaded

Recently uploaded (20)

Info 2102 l4 basic select statement lab1