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

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