Beginning SQL

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Chapter 13 Database Cache 354 In addition to the processor and disk caches, databases build their own cache that resides in system memory. The database cache (illustrated in Figure 13-2) is the only cache discussed so far that you have any direct control over, and you can in fact often tell the DBMS how much memory to request from the system to reserve for caches. In fact, it is often the other way around. With <strong>SQL</strong> Server, you must specify how much main memory not to use — to leave for the server and other applications running on the server. <strong>SQL</strong> Server takes all of the memory less this amount to use for its own purposes, and those purposes are mainly caching data. Hard Disk Cache Figure 13-2 Head of Cache Blocks of Data Data Sent To Processor Cache Back to Head of Cache Tail of Cache Bit Bucket (trash) The database cache looks very similar to the hard disk cache. The biggest difference is the location of the cache. Whereas the hard disk cache physically resides on the hard disk and has to be read into main memory over the cables connecting the disk to the computer, the database cache resides in main memory. When data is read out of this database cache, it is on its way to the processor cache, and from there to the processor itself. Caches in system memory are second only to the processor cache in terms of speed. In today’s hardware, main system memory is approximately 25 to 100 times slower than processor cache; if the processor cache can move data into the processor in a single clock cycle, main memory takes 25 to 100 clock cycles to get the data into the processor. While this sounds a lot slower than processor cache (and it is), it is also the only cache that you have any direct control over, and so it is extremely useful to be aware of this level of caching. If your database is running on a machine with too little main memory, you can often get immense speed gains simply by throwing memory at the problem. At the price of memory today, it may very well cost less to double or quadruple the amount of main memory than for you to spend a week on query optimization. When it comes to databases, the more main memory, the better.
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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
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Example Data This section creates e
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3. Build a record in the Rentals ta
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The other statement that the ANSI S
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SAVE TRANSACTION Select Update Begi
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Figure 11-5 Begin Transaction Delet
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In spite of all of these performanc
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Shared A shared lock essentially me
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of record locks, the DBMS may decid
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No updates, additions, or deletions
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International Board Manufacturer ha
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contention. You could wrap your new
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Summary Transactions ensure that us
Page 696: Chapter 12 328 SQL security is cent
Page 700: Chapter 12 Creating User IDs Figure
Page 704: Chapter 12 3. In the SQL window, ty
Page 708: Chapter 12 ❑ You can assign a dif
Page 712: Chapter 12 Privileges Privileges ar
Page 716: Chapter 12 338 You could then give
Page 720: Chapter 12 You might implement this
Page 724: Chapter 12 Another shortcut, using
Page 728: Chapter 12 As you can imagine, givi
Page 732: Chapter 12 The situation gets a lit
Page 736: Chapter 12 Summary Database securit
Page 740: Chapter 13 robust, fault-tolerant m
Page 744: Chapter 13 Gigahertz Networks or Co
Page 750: The point of all the discussion of
Page 754: How Do You Do It? And herein lies t
Page 758: The slots are often implemented as
Page 762: On the other hand, an index on a tr
Page 766: Tuning Tips The following list cont
Page 770: Database Tuning Exercises 1. Create
Page 776: Appendix A Exercise 2 Solution 368
Page 780: Appendix A ( 8, ‘Jack’, ‘John
Page 784: Appendix A ZipCode, Email, DateOfJo
Page 788: Appendix A Exercise 3 Solution Firs
Page 792: Appendix A 376 Figure A-1 ISBN is a
Page 796: 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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