Chapter 07: Introduction to Structured Query Language (SQL)

TRUE

A database language enables the user to perform complex queries designed to transform the raw data into useful information.

FALSE

SQL is considered difficult to learn; its command set has a vocabulary of more than 300 words.

TRUE

The ANSI SQL standards are also accepted by the ISO.

FALSE

The COMMIT command does not permanently save all changes. In order to do that, you must use SAVE.

FALSE

All SQL commands must be issued on a single line.

TRUE

Although SQL commands can be grouped together on a single line, complex command sequences are best shown on separate lines, with space between the SQL command and the command's components.

FALSE

An alias cannot be used when a table is required to be joined to itself in a recursive query.

FALSE

Oracle users can use the Access QBE (query by example) query generator.

TRUE

You can select partial table contents by naming the desired fields and by placing restrictions on the rows to be included in the output.

FALSE

Comparison operators cannot be used to place restrictions on character-based attributes.

TRUE

String comparisons are made from left to right.

TRUE

Date procedures are often more software-specific than other SQL procedures.

TRUE

SQL allows the use of logical restrictions on its inquiries such as OR, AND, and NOT.

FALSE

You cannot insert a row containing a null attribute value using SQL.

TRUE

ANSI-standard SQL allows the use of special operators in conjunction with the WHERE clause.

TRUE

The conditional LIKE must be used in conjunction with wildcard characters.

FALSE

Most SQL implementations yield case-insensitive searches.

TRUE

Some RDBMSs, such as Microsoft Access, automatically make the necessary conversions to eliminate case sensitivity.

TRUE

The COUNT function is designed to tally the number of non-null 'values' of an attribute, and is often used in conjunction with the DISTINCT clause.

TRUE

Numeric functions take one numeric parameter and return one value.

restricts the selection of grouped rows based on a condition

The SQL data manipulation command HAVING:

COMMIT

The SQL command that allows a user to permanently save data changes is _.

DEFAULT

The _ command defines a default value for a column when no value is given.

HAVING

The _ command restricts the selection of grouped rows based on a condition.

SELECT

A(n) _ query specifies which data should be retrieved and how it should be filtered, aggregated, and displayed.

alias

A(n) _ is an alternate name given to a column or table in any SQL statement.

Operations within parentheses

According to the rules of precedence, which of the following computations should be completed first?

SELECT DISTINCT V_CODE FROM PRODUCT;

Which query is used to list a unique value for V_CODE, where the list will produce only a list of those values that are different from one another?

inner

When using a(n) _ join, only rows from the tables that match on a common value are returned.

natural

A(n) _ join will select only the rows with matching values in the common attribute(s).

JOIN ON

If a designer wishes to create an inner join, but the two tables do not have a commonly named attribute, he can use a(n) _ clause.

outer

A(n) _ join returns not only the rows matching the join condition (that is, rows with matching values in the common columns) but also the rows with unmatched values.

SELECT column-list FROM table1 LEFT [OUTER] JOIN table2 ON join-condition

The syntax for a left outer join is _.

cross

A(n) _ join performs a relational product (also known as the Cartesian product) of two tables.

144

How many rows would be returned from a cross join of tables A and B, if A contains 8 rows and B contains 18?

<>

Which comparison operator indicates a value is not equal?

old-style' join

What type of command does this SQL statement use? SELECT PCODE, PDESCRIPT, PPRICEVNAME FROM PRODUCT, VENDOR WHERE PRODUCT.VCODE=VENDOR. V_CODE

BETWEEN

The special operator used to check whether an attribute value is within a range of values is _.

LIKE

The special operator used to check whether an attribute value matches a given string pattern is _.

COUNT

The SQL aggregate function that gives the number of rows containing non-null values for a given column is _.

subquery

A(n) _ is a query that is embedded (or nested) inside another query.

outer

In subquery terminology, the first query in the SQL statement is known as the _ query.

EXISTS

The special operator used to check whether a subquery returns any rows is _.

The outer subquery initiates the process of execution in a subquery

Which is a feature of a correlated subquery?

DATE()

The _ function returns the current system date in MS Access.

MON

When using the Oracle TODATE function, the code represents a three-letter month name.

LENGTH

_ is a string function that returns the number of characters in a string value.

DECODE

The Oracle _ function compares an attribute or expression with a series of values and returns an associated value or a default value if no match is found.

TO_CHAR()

In Oracle, the _ function converts a date to a character string.

EXCEPT

_ is a relational set operator.

100

The basic SQL vocabulary has fewer than _words.

UNIQUE

The _ specification is used to avoid having duplicated values in a column.

query

In the SQL environment, the word _ covers both questions and actions.

wildcard

A(n) _ character is a symbol that can be used as a general substitute for other characters or commands.

join

The _ condition is generally composed of an equality comparison between the foreign key and the primary key of related tables.

cascading

A(n) _ order sequence is a multilevel ordered sequence that can be created easily by listing several attributes, separated by commas, after the ORDER BY clause.

recursive

An alias is especially useful when a table must be joined to itself in a(n) _ query.

SELECT

The _ command, coupled with appropriate search conditions, is an incredibly powerful tool that enables a user to transform data into information.

Boolean

A specialty field in mathematics, known as _ algebra, is dedicated to the use of logical operators.

conditional

In SQL, all _ expressions evaluate to true or false.

GROUP BY

Rows can be grouped into smaller collections quickly and easily using the _ clause within the SELECT statement.

HAVING

The _ clause of the GROUP BY statement operates very much like the WHERE clause in the SELECT statement.

subquery

A(n) _, also known as a nested query or an inner query, is a query that is embedded (or nested) inside another query.

Oracle

DATE() and SYSDATE are special functions that return today's date in MS Access and _, respectively.

Conversion

_ functions allow you to take a value of a given data type and convert it to the equivalent value in another data type.

Union-compatible

_' means that the names of the relation attributes must be the same and their data types must be alike.

EXCEPT

The _ statement in SQL combines rows from two queries and returns only the rows that appear in the first set but not in the second.

IN

The _ operator could be used in place of INTERSECT if the DBMS does not support it.

NOT IN

The _ operator could be used in place of EXCEPT (MINUS) if the DBMS does not support it.

query EXCEPT query

The syntax of the EXCEPT statement in Oracle is _.