DBMS L8

Retrieving Data Using the SQL SELECT Statement

SELECT

identifies the columns to be displayed

FROM

identifies the table containing those columns.

SELECT *

selecting all columns

SELECT [col_name], [col_name]

selecting specific columns

True

(True or False) SQL statements are not case-sensitive.

true

(True or False) SQL statements can be entered on one or more lines.

true

(True or False) Keywords cannot be abbreviated or split across lines.

true

(True or False) Clauses are usually placed on separate lines.

true

(True or False) Indents are used to enhance readability.

false

(True or False) In SQL Developer, SQL statements can optionally be terminated by a semicolon (;). Semicolons are not required when you execute multiple SQL statements.

True

(True or False) In SQL*Plus, you are required to end each SQL statement with a semicolon (;).

SQL Developer

• Default heading alignment: Left-aligned

• Default heading display: Uppercase

SQL*Plus

• Character and Data column headings are left-aligned.

• Number column headings are right-aligned.

• Default heading display: Uppercase

Arithmetic Expressions

Create expressions with number and date data by using arithmetic operators.

add

+

subtract

-

multiply

*

divide

/

operator precedence

Null

is a value that is unavailable, unassigned, unknown, or inapplicable

false

(True or False) Null is the same as zero or a blank space.

Column Alias

• Renames a column heading

• Immediately follows the column name (There can also be the optional AS keyword between the column name and alias.)

• Requires doubles quotation marks if it contains spaces or special characters, or if it is case-sensitive

Concatenation Operator

• Links columns or character strings to other columns

• Is represented by two vertical bars (||)

• Creates a resultant column that is a character expression

literal

is a character, a number, or a date that is included in the SELECT statement.

Alternative Quote (q) Operator

• Specify your own quotation mark delimiter.

• Select any delimiter.

• Increase readability and usability

DESCRIBE OR DESC

Use this command to display the structure of a table