IE 224 Chapter 2 Questions
In an SQL query, which SQL keyword is used to join two conditions that both must be true for the rows to be selected? A) AND B) EXISTS C) HAVING D) IN E) OR
A
In an SQL query, which SQL keyword is used to specify the names of tables to be joined? A) FROM B) HAVING C) JOIN D) SELECT E) WHERE
A
In an SQL query, which SQL keyword is used with built-in functions to group together rows that have the same value in a specified column? A) GROUP BY B) ORDER BY C) SELECT D) SORT BY E) DISTINCT SET
A
In an SQL query, which built-in function is used to compute the average value of numeric columns? A) AVG B) MEAN C) MAX D) MIN E) SUM
A
In an SQL query, which of the following symbols is used by ANSI SQL to represent a single unspecified character? A) _ (underscore) B) ? (question mark) C) * (asterisk) D) % (percent) E) # (pound)
A
Based on the tables below, which of the following ANSI SQL commands would return the average customer balance grouped by SalesRepNo? GENERAL SALES DATABASE: SALESREP SalesRepNo RepName HireDate 654 Jones 01/02/2005 734 Smith 02/03/2007 345 Chen 01/25/2004 434 Johnson 11/23/2004 CUSTOMER CustNo CustName Balance SalesRepNo 9870 Winston 500 345 8590 Gonzales 350 434 7840 Harris 800 654 4870 Miles 100 345 A) SELECT AVG (Balance) FROM CUSTOMER WHERE SalesRepNo; B) SELECT AVG (Balance) FROM CUSTOMER GROUP BY SalesRepNo; C) SELECT AVG (Balance) FROM CUSTOMER, SALESREP WHERE SALESREP.SalesRepNo = CUSTOMER.SalesRepNo; D) SELECT AVG (Balance) FROM CUSTOMER ORDER BY SalesRepNo; E) SELECT AVG (Balance) FROM CUSTOMER, SALESREP WHERE CUSTOMER.SalesRepNo = CUSTOMER.SalesRepNo HAVING SalesRepNo;
B
In an SQL query, which SQL keyword is used to sort the result table by the values in one or more columns? A) GROUP BY B) ORDER BY C) SELECT D) SORT BY E) WHERE
B
In an SQL query, which SQL keyword is used to specify the table(s) to be used? A) EXISTS B) FROM C) SELECT D) SET E) WHERE
B
In an SQL query, which SQL keyword must be used to remove duplicate rows from the result table? A) DELETE B) DISTINCT C) NOT EXISTS D) UNIQUE E) KEY
B
In an SQL query, which built-in function is used to compute the number of rows in a table? A) AVG B) COUNT C) MAX D) MIN E) MEAN
B
In an SQL query, which of the following symbols is used by Microsoft Access to represent a single unspecified character? A) _ (underscore) B) ? (question mark) C) * (asterisk) D) % (percent) E) # (pound)
B
Regarding the interchangeability of subqueries and joins, A) a join can always be used as an alternative to a subquery, and a subquery can always be used as an alternative to a join. B) a join can sometimes be used as an alternative to a subquery, and a subquery can sometimes be used as an alternative to a join. C) a join can always be used as an alternative to a subquery, and a subquery can sometimes be used as an alternative to a join. D) a join can sometimes be used as an alternative to a subquery, and a subquery can always be used as an alternative to a join. E) a join can never be used as an alternative to a subquery, and a subquery can never be used as an alternative to a join.
B
When making an SQL query, we are using SQL as a(n) ________. A) DDL B) DML C) embedded language D) SET E) WHERE
B
Given a table with the structure: EMPLOYEE (EmpNo, Name, Salary, HireDate), which of the following would find all employees whose name begins with the letter "S" using Microsoft Access? A) SELECT * FROM EMPLOYEE WHERE Name IN ['S']; B) SELECT EmpNo FROM EMPLOYEE WHERE Name LIKE 'S'; C) SELECT * FROM Name WHERE EMPLOYEE LIKE 'S*'; D) SELECT * FROM EMPLOYEE WHERE Name LIKE 'S%'; E) None of the above.
C
In an SQL query, which SQL keyword actually creates the query? A) EXISTS B) FROM C) SELECT D) SET E) WHERE
C
In an SQL query, which SQL keyword is used with GROUP BY to select groups meeting specified criteria? A) AND B) EXISTS C) HAVING D) IN E) WHERE
C
In an SQL query, which built-in function is used to obtain the largest value of numeric columns? A) AVG B) COUNT C) MAX D) MIN E) SUM
C
In an SQL query, which of the following symbols is used by ANSI SQL to represent all the columns in a single table? A) _ (underscore) B) ? (question mark) C) * (asterisk) D) % (percent) E) # (pound)
C
When one SQL query is embedded in another SQL query, the second SQL query is embedded in the ________ of the first query. A) SELECT B) FROM C) WHERE D) GROUP BY E) HAVING
C
Based on the tables below, which of the following commands in ANSI SQL would return only the name of the sales representative and the name of the customer for each customer that has a balance greater than 400? GENERAL SALES DATABASE: SALESREP SalesRepNo RepName HireDate 654 Jones 01/02/2005 734 Smith 02/03/2007 345 Chen 01/25/2004 434 Johnson 11/23/2004 CUSTOMER CustNo CustName Balance SalesRepNo 9870 Winston 500 345 8590 Gonzales 350 434 7840 Harris 800 654 4870 Miles 100 345 A) SELECT * FROM SALESREP, CUSTOMER WHERE Balance > 400; B) SELECT DISTINCT RepName, CustName FROM SALESREP, CUSTOMER WHERE Balance > 400; C) SELECT * FROM SALESREP, CUSTOMER WHERE SALESREP.SalesRepNo = CUSTOMER.SalesRepNo AND Balance > 400; D) SELECT RepName, CustName FROM SALESREP, CUSTOMER WHERE SALESREP.SalesRepNo = CUSTOMER.SalesRepNo AND Balance > 400; E) SELECT RepName, CustName FROM SALESREP, CUSTOMER WHERE Balance > 400 GROUP BY SalesRepNo;
D
Given a table with the structure: EMPLOYEE (EmpNo, Name, Salary, HireDate), which of the following is not a valid ANSI SQL command? A) SELECT * FROM EMPLOYEE WHERE Name LIKE 'Ja%'; B) SELECT COUNT(*) FROM EMPLOYEE WHERE Salary < 30000; C) SELECT COUNT(EmpNo) FROM EMPLOYEE; D) SELECT HireDate, COUNT(*) FROM EMPLOYEE WHERE Salary < 30000; E) SELECT HireDate, COUNT(*) FROM EMPLOYEE GROUP BY HireDate;
D
Given a table with the structure: EMPLOYEE (EmpNo, Name, Salary, HireDate), which of the following would find all employees whose name begins with the letter "S" using standard SQL? A) SELECT * FROM EMPLOYEE WHERE Name IN ['S']; B) SELECT EmpNo FROM EMPLOYEE WHERE Name LIKE 'S'; C) SELECT * FROM Name WHERE EMPLOYEE LIKE 'S*'; D) SELECT * FROM EMPLOYEE WHERE Name LIKE 'S%'; E) None of the above.
D
In an SQL query of two tables, which SQL keyword indicates that we want data from all the rows of one table to be included in the result, even if the row does not correspond to any data in the other table? A) LEFT JOIN B) RIGHT JOIN C) INCLUDE D) A and B E) A, B, and C
D
In an SQL query, the built-in functions SUM and AVG work with columns containing data of which of the following data types? A) Integer B) Numeric C) Char D) A and B E) A, B, and C
D
In an SQL query, which SQL keyword is used to determine if a column value is equal to any one of a set of values? A) AND B) EXISTS C) HAVING D) IN E) OR
D
In an SQL query, which SQL keyword is used to implement a subquery? A) GROUP BY B) HAVING C) ORDER BY D) SELECT E) SORT BY
D
In an SQL query, which built-in function is used to obtain the smallest value of numeric columns? A) AVG B) COUNT C) MAX D) MIN E) SUM
D
When one SQL query is embedded in another SQL query, this is referred to as a ________. A) subset B) join C) WHERE Query D) subquery E) set query
D
In an SQL query, the built-in function COUNT works with columns containing data of which of the following data types? A) Integer B) Numeric C) Char D) A and B E) A, B, and C
E
In an SQL query, which SQL keyword is used to specify the column names to be used in a join? A) FROM B) HAVING C) JOIN D) SELECT E) WHERE
E
In an SQL query, which SQL keyword is used to state the condition that specifies which rows are to be selected? A) EXISTS B) FROM C) SELECT D) SET E) WHERE
E
In an SQL query, which built-in function is used to total numeric columns? A) AVG B) COUNT C) MAX D) MEAN E) SUM
E
SQL is a ________. A) data sublanguage B) product of IBM research C) national standard D) combination that includes a data definition language and a data manipulation language E) All of the above
E
When one SQL query is embedded in another SQL query, the first SQL query can still contain an SQL ________ clause. A) FROM THE B) WHERE THE C) ORDER BY D) GROUP BY E) C and D
E
A WHERE clause can contain only one condition.
F
Arithmetic in SQL statements is limited to the operations provided by the built-in functions.
F
Every subquery can be alternatively expressed by a join.
F
In addition to being a data sublanguage, SQL is also a programming language, like Java or C#.
F
Only two tables can be queried by using a subquery.
F
Outer joins can be either up joins or down joins.
F
SQL can only query a single table.
F
SQL is only a data manipulation language (DML).
F
SQL stands for Standard Query Language.
F
SQL statements end with a colon.
F
SQL, although very popular, has never become a national standard.
F
Sorting is specified by the use of the SORT BY phrase.
F
The Microsoft Access wildcard character "_" (underscore) indicates a single, unspecified character in a specific location in a Microsoft Access SQL query.
F
The SQL built-in function ADDUP totals values in numeric columns.
F
The SQL keyword WHERE is used to specify the table(s) that contain(s) the data to be retrieved.
F
The SQL wildcard character "#" indicates a single, unspecified character in a specific location in an SQL query.
F
The WHERE clause contains the condition that specifies which columns are to be selected.
F
The built-in function SUM can be used with any column.
F
The columns to be obtained by an SQL command are listed after the FROM keyword.
F
To exclude one or more values using a condition, the SQL OUT keyword must be used.
F
To have SQL automatically eliminate duplicate rows from a result, use the keyword DISTINCT with the FROM keyword.
F
To sort the rows of the result table, the ORDER BY clause is specified.
F
Two or more tables are joined by giving the table names in the WHERE clause and specifying the equality of the respective column names as a condition in the GROUP BY clause.
F
Explain why it is important to learn SQL.
Most modern DBMS products support SQL as a standardized data language. These products usually provide graphical tools to perform the tasks associated with SQL, but there are some tasks that cannot be performed using these graphical tools. SQL is text-oriented, and SQL code must be written in order to embed SQL commands within program applications.
What is SQL?
Structured Query Language (SQL) is used to create and use databases, tables and relationships. SQL is divided into two categories: SQL statements for database definition and SQL statements for database processing (querying and updating). The database definition commands are referred to as a data definition language (DDL), and the database query and update commands are referred to as a data manipulation language (DML). SQL was developed by IBM, and is endorsed as a national standard by the American National Standards Institute (ANSI). Although a newer standard, SQL3, exists, the most widely implemented version of SQL is the ANSI SQL-92 standard. SQL is not a full-featured programming language, but rather it is considered to be a data sublanguage.
Briefly describe subqueries and joins. Explain when each is not an acceptable alternative for the other.
Subqueries and joins are both methods for retrieving data from multiple tables. Subqueries involve nesting one SELECT statement within another. The nested SELECT is used as part of a condition in the WHERE clause of the first SELECT statement. The nested SELECT statement can return a set of records from one table, which are then used in a logical operator within the parent SELECT query. A join combines records from each table into concatenated records containing the fields of both tables. The records are concatenated based on matching values in similar columns in the two tables. Subqueries cannot be used in situations where the results to be displayed include attributes from more than one table. Joins cannot be used as an alternative to a correlated subquery.
A SELECT statement used in a WHERE clause is called a subquery.
T
A WHERE clause can contain another SELECT statement enclosed in parentheses.
T
A nested SELECT statement (one that appears within the WHERE clause of another SQL statement) is called a subquery and must be enclosed in parentheses.
T
An alternative to combining tables by a subquery is to use a join.
T
An asterisk (*) following the SELECT verb means that all columns are to be displayed.
T
Columns can be sorted in descending sequence by using the SQL DESC keyword.
T
In an SQL query, a join operation is achieved by specifying the equality of the respective column names as a condition in the WHERE clause.
T
Joins that show only matching rows from the joined tables in their results are called inner joins.
T
Joins that show the matching rows from the joined tables plus unmatched rows from one other table in their results are called outer joins.
T
SQL commands can be embedded in application programs.
T
SQL includes a data definition language, a data manipulation language, and SQL/Persistent stored modules.
T
SQL is not a complete programming language. Rather it is a data sublanguage.
T
SQL was developed by IBM in the late 1970s.
T
The American National Standards Institute (ANSI) maintains the standards for SQL.
T
The Microsoft Access wildcard character "*" (asterisk) indicates a sequence of one or more unspecified characters in a Microsoft Access SQL query.
T
The SQL WHERE clause contains the condition that specifies which rows are to be selected.
T
The SQL built-in function AVG computes the average of values in numeric columns.
T
The SQL built-in function COUNT computes the number of rows in a query.
T
The SQL built-in function MIN obtains the smallest value in a numeric column.
T
The SQL built-in function MOST obtains the largest value in a numeric column.
T
The SQL keyword FROM is used to specify the table to be used.
T
The SQL keyword GROUP BY instructs the DBMS to group together those rows that have the same value in a column.
T
The SQL keyword LIKE is used in SQL expressions to select on partial values.
T
The SQL keyword SELECT is used to specify the columns to be listed in the query results. Answer: TRUE
T
The SQL syntax JOIN . . . ON can be used as alternate way of writing an SQL join statement.
T
The SQL wildcard character "%" represents a series of one or more unspecified characters.
T
The clause SELECT COUNT (*) results in a table with a single row and a single column.
T
The condition in WHERE clauses can refer to a set of values by using the IN operator.
T
The names of tables to be joined in an SQL query are listed in the FROM clause.
T
The result of an SQL SELECT operation can contain duplicate rows.
T
The rows of the result table can be sorted by the values in one or more columns.
T
To obtain all columns, use an asterisk (*) wildcard character instead of listing all the column names.
T
To refer to a set of values in a condition, the values are placed inside parentheses ( ) and separated by commas.
T
To refer to a set of values needed for a condition, use the SQL IN operator.
T
To remove duplicate rows from the result of a query, specify the SQL DISTINCT keyword.
T
When people use the term "join" they normally mean an "equijoin."
T
When two conditions must both be true for the rows to be selected, the conditions are separated by the SQL AND keyword.
T
While many subqueries can be alternatively written as joins, correlated subqueries do work that cannot be duplicated as a join.
T
The following database will be used in this question: GENERAL SALES DATABASE: SALESREP SalesRepNo RepName HireDate 654 Jones 01/02/2005 734 Smith 02/03/2007 345 Chen 01/25/2004 434 Johnson 11/23/2004 CUSTOMER CustNo CustName Balance SalesRepNo 9870 Winston 500 345 8590 Gonzales 350 434 7840 Harris 800 654 4870 Miles 100 345 Explain the use of the SQL keyword LIKE. Include an example based on the CUSTOMER table from the General Sales database.
The LIKE keyword is used in the WHERE clause of an SQL query to select rows based on partial values. Through the use of wildcard characters that can represent one or more unspecified characters, the LIKE operator can search for a given string of characters within a column value. The ANSI wildcard "%" represents one or more unspecified characters, and the wildcard " " (underscore) represents any single unspecified character. For example, SELECT * FROM CUSTOMER WHERE CustName LIKE 'H%'; is a query that returns all information in the table CUSTOMER about customers whose CustName starts with the letter H.
The following database will be used in this question: GENERAL SALES DATABASE: SALESREP SalesRepNo RepName HireDate 654 Jones 01/02/2005 734 Smith 02/03/2007 345 Chen 01/25/2004 434 Johnson 11/23/2004 CUSTOMER CustNo CustName Balance SalesRepNo 9870 Winston 500 345 8590 Gonzales 350 434 7840 Harris 800 654 4870 Miles 100 345 Explain the use of the of SQL keyword SELECT. Include an example based on the CUSTOMER table in the General Sales database.
The SQL keyword SELECT forms the basis for all SQL querying. Although SELECT technically specifies columns to be used in a query, it is always the first SQL keyword or command in an SQL phrase that includes at least the SQL keyword FROM and often the SQL keyword WHERE. The SQL keyword WHERE is used to specify which tables are used in the query, while the SQL keyword WHERE is used to specify conditions or constraints imposed on the query. For example, SELECT * FROM CUSTOMER WHERE CustNo = 34567; is a query that returns all information in the table CUSTOMER about the customer whose customer number is 34567.
