Saturday, March 29, 2008

FAQ - Database Testing (141 to 150)

141. The most important DDL statements in SQL are:

CREATE TABLE - creates a new database table
ALTER TABLE - alters (changes) a database table
DROP TABLE - deletes a database table
CREATE INDEX - creates an index (search key)
DROP INDEX - deletes an index

142. Operators used in SELECT statements.

= Equal
<> or != Not equal
> Greater than
<>= Greater than or equal
<= Less than or equal BETWEEN Between an inclusive range LIKE Search for a pattern

143. SELECT statements:


SELECT column_name(s) FROM table_name
SELECT DISTINCT column_name(s) FROM table_name
SELECT column FROM table WHERE column operator value
SELECT column FROM table WHERE column LIKE pattern
SELECT column,SUM(column) FROM table GROUP BY column
SELECT column,SUM(column) FROM table GROUP BY column HAVING SUM(column) condition value
Note that single quotes around text values and numeric values should not be enclosed in quotes. Double quotes may be acceptable
in some databases.

144. The SELECT INTO Statement is most often used to create backup copies of tables or for archiving records.

SELECT column_name(s) INTO newtable [IN externaldatabase] FROM source
SELECT column_name(s) INTO newtable [IN externaldatabase] FROM source WHERE column_name operator value

145. The INSERT INTO Statements:

INSERT INTO table_name VALUES (value1, value2,....)
INSERT INTO table_name (column1, column2,...) VALUES (value1, value2,....)

146. The Update Statement:

UPDATE table_name SET column_name = new_value WHERE column_name = some_value

147. The Delete Statements:

DELETE FROM table_name WHERE column_name = some_value
Delete All Rows:
DELETE FROM table_name or DELETE * FROM table_name

148. Sort the Rows:

SELECT column1, column2, ... FROM table_name ORDER BY columnX, columnY, ..
SELECT column1, column2, ... FROM table_name ORDER BY columnX DESC
SELECT column1, column2, ... FROM table_name ORDER BY columnX DESC, columnY ASC

149. The IN operator may be used if you know the exact value you want to return for at least one of the columns.

SELECT column_name FROM table_name WHERE column_name IN (value1,value2,..)

150. BETWEEN ... AND

SELECT column_name FROM table_name WHERE column_name BETWEEN value1 AND value2 The values can be numbers, text, or dates.

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