Beginning SQL

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Setting up security begins with creating user IDs and passwords. How this is done varies enormously from DBMS to DBMS. In fact, some DBMSs can have the operating system itself perform all user/password validations for it and simply use the operating system username in the DBMS. For the purposes of this chapter, you can assume that user IDs and passwords are created in the DBMS. You may need to do a little digging to determine specifically how it is done in your OS and DBMS. User IDs SQL Security Users IDs are the foundation of SQL security. At least one user ID is created by the database, known variously as the database owner (DBO), system administrator (SA), or something similar. This user is a superuser who starts the ball rolling, typically creating the first tables and creating the user IDs of all the other users allowed in the table. In simple databases, it is quite common for all users to log in as the system administrator, which means that every user has all privileges to all objects. Anyone can do anything to any database object. In a small office where there is no one capable of understanding and maintaining database security, this may be an appropriate model, but for large corporations this is a recipe for disaster. In a secure DBMS, a user ID is a name/password pair that allows some entity to perform actions in the database. The entity may be a person, a program, or a program directly manipulated by a person, but the end result is that the entity has to log in to the database, providing a valid username and password. The DBMS looks up the username and password, performs validation to ensure that that pair is legal in the system, and then determines what the user is allowed to do in the database. In a database where security is implemented, a user is typically assigned a user ID and the user ID is assigned a password. The user ID then becomes the central character in the security system. Every SQL statement is executed on behalf of a user ID, and the privileges assigned to a user ID determine which statements can legally be performed by that user ID. User IDs are not necessarily used by people, however; machines quite often add, delete, and update records in databases with no input from any specific person. Machines in factories log production or assembly of objects, airplanes log sensor inputs from throughout the aircraft, and so forth. In Figure 12-2, Mary, Sue, and John from the Personnel department are all given a common user ID and password. In some respects, this emulates the creation of a group with users assigned to the group. Betty, the personnel manager, has been given a unique user ID and password. Likewise, Cyndi has been given her own user ID and password. Technically, the user ID is the object internal to the database, and the user is someone or something in the real world using a user ID to manipulate data. For ease of discussion, user is equated to user ID, but understand that they are not the same thing. DBMSs vary widely in how a user is validated. For example, the user may be required to log in to the DBMS directly, providing a username and password. On the other hand, the DBMS may accept user validation performed by the operating system: The user logs in to Windows, and the DBMS then accepts the username and password from Windows and looks up that username to determine whether to allow privileges. However, before a user can do anything in the DBMS, the system administrator must create the user and define which privileges he or she has. 329
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Beginning SQL Paul Wilton and John
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Beginning SQL Paul Wilton and John
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About the Authors Paul Wilton After
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Paul Wilton: With lots of love to m
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Contents x Selecting Correct Data T
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Contents xii Re-examining NULL 180
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Contents Chapter 11: Transactions 3
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Contents xvi How Do You Do It? 357
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Introduction Data, data, data! Data
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By the time you’ve completed Chap
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Once you download the code, just de
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1 Introduction to SQL A nice, gentl
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Figure 1-1 Why and When to Use a Da
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Databases are great at dealing with
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The SQL language is actually fairly
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you wish, and the database system d
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A keyword is a word that has some m
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Introduction to SQL A perfectly val
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Data Type Description Storage Used
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The char and varchar data types use
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Most RDBMSs handle the most common
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To add a new column, use the basic
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Now that you know what you want to
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❑ Meeting date 2 ❑ Location 2
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Generally speaking, picking a data
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example, the MemberId field links t
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Depending on which RDBMS you’re u
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The FilmCategory table is very smal
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2 Entering Information The last cha
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like this: INSERT INTO Category VAL
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Inserting Data into the Case Study
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The WHERE Clause So far you’ve se
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Try It Out Using Logical Operators
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Exercises 1. Three new members have
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Chapter 3 54 MemberId FirstName 1 K
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Chapter 3 The results are as follow
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Chapter 3 The results to this query
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Chapter 3 FavCategory (CategoryId,
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Chapter 3 Logical Operators and Ope
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Chapter 3 The statement returns the
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Chapter 3 NOT Operator Examples thu
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Chapter 3 2. Using the following SQ
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Chapter 3 When you execute the quer
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Chapter 3 Now that you’re acquain
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Chapter 3 It’s as simple as that!
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Chapter 3 76 YearReleased 1947 1967
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Chapter 3 78 FilmName Rating Gone w
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Chapter 3 2. Add a WHERE clause to
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Chapter 3 Executing this SQL provid
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Chapter 3 84 FullName First name is
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Chapter 3 86 FullName First name is
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Chapter 3 Even though DateOfBirth i
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Chapter 3 Member Name The member is
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Chapter 3 92 The preceding SQL prod
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Chapter 3 94 ❑ Category ❑ FavCa
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Chapter 3 96 You’re one step furt
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Chapter 3 98 FirstName LastName Cat
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Chapter 3 This time, you achieve mo
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Chapter 3 SQL Is Set-Based 102 You
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Chapter 3 104 Category MemberId Thr
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Chapter 3 106 You should see the fo
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Chapter 3 The overlapping portions
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Chapter 3 110 More than one conditi
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Chapter 3 112 Next, link the Member
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Chapter 3 114 FirstName LastName Da
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Chapter 3 ❑ The slightly tricky t
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Chapter 4 normalization can make da
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Chapter 4 120 Field Name Data Type
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Chapter 4 122 The Street, City, and
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Chapter 4 MySQL versions prior to 5
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Chapter 4 126 Except for IBM’s DB
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Chapter 4 128 You can add more than
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Chapter 4 Try It Out Adding a CHECK
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Chapter 4 Obviously, if the table i
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Chapter 4 134 Drop the MoreHolidayB
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Chapter 4 136 If you want to return
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Chapter 4 If you’re using IBM DB2
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Chapter 4 140 index helps speed up
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Chapter 4 142 The results you get m
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Chapter 4 144 The results of the qu
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Chapter 4 146 Remember, IBM DB2 doe
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Chapter 4 148 UPDATE Films SET Film
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Chapter 4 150 Finally, you do the s
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Chapter 4 152 SELECT * FROM MemberD
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Chapter 4 ❑ Choose meaningful nam
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5 Manipulating Data In Chapter 3, y
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The results of this query are as fo
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You can raise a number to any power
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To demonstrate the sort of results
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The CEILING() Function The CEILING(
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ased on the digits after the decima
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The SUBSTRING() function works at t
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LastName UPPER(LastName) LOWER(Last
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The LENGTH() function takes just on
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LastName LOWER(SUBSTRING(LastName,1
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FirstName DIFFERENCE(FirstName, ‘
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Converting Different Data Types Thi
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CREATE Table MyTable(FirstColumn in
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The COALESCE() Function The COALESC
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Ideally, this first argument is the
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LocationId Street City State 1 Main
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6 Grouping and Aggregating Data So
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Running the query, complete with a
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MemberId Street City State 11 Newis
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Executing the SQL returns seven dis
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For example, the following code add
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Running the query gives the answer
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SELECT MAX(LastName), MIN(LastName)
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immediately after the GROUP BY stat
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Executing the final SQL provides th
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Chapter 7 The INNER JOIN links the
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Chapter 7 FilmName FirstName LastNa
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Chapter 7 212 As mentioned, that wo
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Chapter 7 Category Street Romance T
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Chapter 7 216 MD1.First MD1.Last MD
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Chapter 7 SELECT MD1.MemberId, MD1.
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Chapter 7 220 SELECT Category, Film
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Chapter 7 222 Location.Street Membe
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Chapter 7 224 Category MemberId War
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Chapter 7 Look at the results that
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Chapter 7 228 The Maltese Poodle 8
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Chapter 7 230 9 10 11 12 13 14 15 1
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Chapter 7 232 On Golden Puddle 1967
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8 Queries within Queries This chapt
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There are no films with a value in
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The error wording depends on the da
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Now execute the query. You receive
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The query provides the following re
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If you execute this query, you can
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To obtain the same results as you w
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MemberId 1 10 14 6 5 8 7 11 15 4 13
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Now NOT EXISTS returns true, and as
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This is the same as the query just
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clause specifying that the film’s
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4. Next, quickly double-check a few
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Now that you’ve confirmed that th
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Summary Queries within Queries This
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Chapter 9 264 Figure 9-1 The SQL ne
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Chapter 9 266 INSERT INTO OrderItem
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Chapter 9 268 VALUES (5,7, 2,’200
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Chapter 9 Now that you’ve added t
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Chapter 9 272 FirstName LastName Mo
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Chapter 9 274 DVDPrice column is in
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Chapter 9 SalesPersonId FirstName L
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Chapter 9 278 SalesPersonId MemberI
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Chapter 9 280 SalesPersonId MemberI
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Chapter 9 282 MemberDetails.FirstNa
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Chapter 9 284 The query would work
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Chapter 9 Exercises 286 Assume that
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Chapter 10 Now that you know what v
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Chapter 10 Types of Views Given tha
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Chapter 10 Perhaps you need to view
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Chapter 10 Figure 10-7 Summary view
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Chapter 10 296 This statement gives
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Chapter 10 The CHECK OPTION plays a
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11 Transactions When you move out o
Page 646: Example Data This section creates e
Page 650: 3. Build a record in the Rentals ta
Page 654: The other statement that the ANSI S
Page 658: SAVE TRANSACTION Select Update Begi
Page 662: Figure 11-5 Begin Transaction Delet
Page 666: In spite of all of these performanc
Page 670: Shared A shared lock essentially me
Page 674: of record locks, the DBMS may decid
Page 678: No updates, additions, or deletions
Page 682: International Board Manufacturer ha
Page 686: contention. You could wrap your new
Page 690: Summary Transactions ensure that us
Page 696: Chapter 12 328 SQL security is cent
Page 702: ALTER USER username options ALTER U
Page 706: In Figure 12-3, three different gro
Page 710: How It Works After you run this sta
Page 714: check constraints can be used in a
Page 718: You could then give SELECT privileg
Page 722: Limitations on Views Views are by t
Page 726: GRANT SELECT (NAME, SSN, SALARY) ON
Page 730: Betsey also grants privileges to Ji
Page 734: The CASCADE option tells the DBMS t
Page 738: 13 Database Tuning SQL is a languag
Page 742: Perhaps this doesn’t sound remote
Page 746: When an application asks for data f
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The point of all the discussion of
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How Do You Do It? And herein lies t
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The slots are often implemented as
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On the other hand, an index on a tr
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Tuning Tips The following list cont
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Database Tuning Exercises 1. Create
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Appendix A Exercise 2 Solution 368
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Appendix A ( 8, ‘Jack’, ‘John
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Appendix A ZipCode, Email, DateOfJo
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Appendix A Exercise 3 Solution Firs
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Appendix A 376 Figure A-1 ISBN is a
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Appendix A Chapter 5 Exercise 1 Sol
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Appendix A 380 You might receive sl
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Appendix A 382 You should use the f
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Appendix A Your answer may differ,
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Appendix A WHERE (SELECT COUNT(*) f
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Appendix A Exercise 2 Solution CREA
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Appendix A Chapter 13 Exercise 1 So
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Appendix B 392 Click the database i
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Appendix B 394 Click Install to beg
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Appendix B 396 Select the Detailed
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Appendix B 398 Leave it at the defa
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Appendix B 400 Having entered your
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Appendix B 402 Figure B-20 The inst
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Appendix B 404 At the very top of t
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Appendix B 406 Having done that, ma
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Appendix B 408 Figure B-30 MyTable
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Appendix B 410 Figure B-32 Click Ne
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Appendix B 412 Click Next to contin
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Appendix B 414 Click OK to clear th
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Appendix B If you’re ready and ha
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Appendix B 418 You can also enter a
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Appendix B 420 Figure B-49 The Film
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Appendix B 422 Now you need to inse
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Appendix B 424 In Access it’s not
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Appendix B 426 Figure B-56 You need
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Appendix B 428 Then click the Run i
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Appendix B 430 The next screen (see
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Appendix B 432 On the next screen,
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Appendix B 434 Click Next to procee
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Appendix B 436 Figure B-72 The huge
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Appendix B 438 Figure B-74 Notice t
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Appendix B 440 Figure B-76 The Obje
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Appendix B 442 Figure B-78 Chapter
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Appendix B You don’t need MyTable
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Appendix B 446 Figure B-82 To begin
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Appendix B Using Oracle’s SQL*Plu
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Appendix B 450 Figure B-87 Another
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Appendix C Category Table The follo
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Appendix C 454 ( 3, ‘Sandra’,
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Appendix C 456 ZipCode, Email, Date
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Appendix C DateOfJoining ) VALUES (
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Appendix C 460 VALUES ( 1, 3 ); INS
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Appendix C VALUES ( 5, 3 ); INSERT
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Appendix C 464 3 ); INSERT INTO Fil
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Appendix C 5, 6 ); INSERT INTO Film
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Appendix C 468 5 ); INSERT INTO Att
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Appendix C Oracle 470 To save some
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Appendix C 472 LocationId, MeetingD
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Symbols + (addition operator), 82,
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BEGIN TRANSACTION statement, 306, 3
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SERIALIZABLE statement, 318 SET TRA
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data types brackets, 25 categories,
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Oracle concatenation, 85-88 configu
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error messages debugging, 26 subque
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concatenation, 85-88 data type comp
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primary keys database creation exam
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concurrent connection selection, 39
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passwords group access, 333 IBM ins
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ROLLBACK statement, 307-308 ROLLBAC
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REPEATABLE READ, 319 REVOKE, 344-34
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telephone numbers, data type select
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historical, data selection, 90-94 N
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Beginning SQL

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