MySQL Certification Stydy Guide Errata
The data below is a copy of the official errata page (as hosted by mysql.com) that i made when i was preparing myself for the developer exams. I'm not sure if it is the most recent version that has been published, but hey, it's better than nothing.
The reasons for putting this online can be read here
Exam Updates after the publication of the Study Guide
The MySQL 5.0 Certification Study Guide was written
before the completion of the certification exams. At that time,
it was expected that questions on MySQL Administrator
and MySQL Query Browser would be part of the exam. For a
number of technical reasons, questions on these two products
do not appear on the final version of the exams.
- Contents at a Glance: The chapter "The
Client Program" starts on page 35, not 25.
- Acknowledgments: Delete one instance of "and initiate the".
- Page 8+9: The distribution of questions within the exams have
since the publication of the book. Replace the two tables with the
|Table IN.1: Division of Questions on Exam Sections for the
|MySQL Developer I Exam
||MySQL Developer II Exam
|The mysql Client Program
||Importing and Exporting Data
|Tables and Indexes
|Querying for Data
||Obtaining Database Metadata
||Debugging MySQL Applications
|Table IN.2: Division of Questions on Exam Sections for the DBA
|MySQL DBA I Exam
||MySQL DBA II Exam
|Starting, Stopping and Configuring MySQL
|Client Programs for DBA Work
||Securing the Server
|Character Set Support
||Upgrade-Related Security Issues
||Optimizing the Server
|The INFORMATION_SCHEMA Database
||Interpreting Error Messages
|Data Backup and Recovery Methods
||Optimizing the Environment
- Page 10+11: In both figure captions, replace 'status
bar says "select' with 'status bar indicates "Select'. Also for both
captions, add a closing '"' last in the paragraph. In Figure IN,3,
the last word should be "responses", not "answers".
- Page 10, last paragraph: Replace 'status line says' with
'status line indicates'.
- Page 15, last line: replace 'Country' with 'CountryCode'.
- Page 32, line 11:
sql_mode='TRADITIONAL"; should read:
sql_mode='TRADITIONAL'; (i.e. change double-quote to
- Page 48: Last word on the page should be "them", not "then".
- Page 61: In the table at the bottom of the page, the lowest
value for a signed
INT is stated as "-2,147,683,648".
It should be: "-2,147,483,648".
- Page 69, second paragraph: Padding is done with null bytes, not spaces. But BINARY columns are not stripped of null bytes. The length of a retrieved column BINARY(M) is always M.
- Page 72, third paragraph of section 5.5: Replace "and '00:00:00'
for TIME) values." with "and '00:00:00' for TIME values)."
- Page 73: 6th paragraph (the first of the two starting with "MySQL
time values...") should be deleted.
- Page 73, last paragraph: The last two instances of
TIME" should be replaced with "time", so the
end of the paragraph reads: "...It's similar to a combination
TIME values, but the
time part represents time of day rather than elapsed time and
has a range limited to
'23:59:59'. The date part of
has the same range as DATE columns; combined with the
time part, this results in a
DATETIME range from
'1000-01-01 00:00:00' to
- Page 88: The
CREATE TABLE statement of the 2nd
bulletpoint (line 13) should include the
CREATE TABLE t (id INT NOT NULL AUTO_INCREMENT,
(MySQL will add this implicitly for any
PRIMARY KEY or
AUTO_INCREMENT declaration in the field
- Page 89, last bullet point: Add "If the server is restarted, InnoDB
will start incrementing from the high end of the sequence, ignoring
AUTO_INCREMENT values that have been created and then
deleted from the high end."
- Page 98, section 6.2: Table aliases are governed by the same rules
- Page 114, first line: replace "you convert" with "you to convert".
- Page 122, section 8.6.1, first bullet point: add "A table may contain only one primary key."
- Page 217, 2nd bullet point of section 12.2.2: Add: "With USING(), only
the column of the table mentioned first in the join will be part of the
result set. The (redundant) column of the second table mentioned will
not be included in the result."
- Page 232, Last paragraph and accompanying example ("Compare that
query to the following one...". The meaning attributed to the SQL
statement in this example is incorrect. The example should be ignored.
- Page 233. The discussion indicating the SOME is a synonym for ANY
includes an example SQL statement. The meaning attributed to this
statement is incorrect. The example should be ignored. The modified
discussion after removing the example should read:
The word SOME is an alias for ANY, and may be used anywhere that ANY
is used. The SQL standard defines these two words with the same
meaning to overcome a limitation in the English language,
particularly for inequality comparisons. In the English language, we
expect "not any" to mean "none at all." However, in SQL, <> ANY
means "one or more do not match." To alleviate the confusion that
might arise from the use of <> ANY, the SQL standard includes the
SOME keyword as a synonym for ANY. Using the <> SOME construct makes
it easier to understand the expected outcome of such SQL statements.
- Page 308: First paragraphs of section 19.2: Replace the text
"Each trigger for a given table must ..." to the end of the paragraph
with "Each trigger within a database must have a different name."
- Page 311: Delete first bullet point ("You cannot use the CALL
- Page 311, 2nd paragraph from bottom: Delete from "In MySQL, the syntax
requires... " until the end of the paragraph.
- Page 328, third paragraph: Replace "For the
statement" with "For the
- Page 337 and 338: All instances of "
YEAR" should read
- Page 340: Replace the first 3 paragraphs (up to and including "doesn't
retrieve as many rows in the first place") with the following:
In general, you should try to use a WHERE clause to restrict
the server only retrieves the number of rows actually needed. Some uses
of LIMIT, such as
SELECT * FROM t LIMIT 10;
will be fast. However, for result sets with millions of rows a statement
SELECT * FROM ... LIMIT 2000000, 10;
is not very efficient.
- Page 352, 6th line of 3rd paragraph: Replace "OBDC" with "ODBC".
- Page 368, last bullet point before section 24.4: Replace "the Perl DBI module" with "Perl".
- Page 404: replace "byacquiring" with "by acquiring".
- Page 411, first bullet point: Replace "begin" with "begun".
- Page 430:
SHOW ENGINEINNODB STATUS should read
ENGINE INNODB STATUS
- Page 432, last paragraph: Replace "stored" with "storage".
- Page 453, First paragraph of section 32.3.1: Replace ".MYD and .MYI
files" with ".MYD, .MYI and .TRG files".
- Page 454, 5th paragraph (section "3"): Add new bulletpoint:
"Any .TRG file(s) associated with the tables being backed up.
- Page 461, section 32.5: Delete first bullet point.
- Page 490, 6th line from the bottom: replace "
FLUSH PRIVILEGES statement".
- Page 500, section 35.6: In the last line of the
TABLE statement, replace
CONNECTION=. (Changed in MySQL 5.0.13).
- Page 543, third bullet point: delete ", which allows their contents to
be read in parallel".
- Exercises, Client/Server Concepts: For the exercise that starts with
"Suppose that you invoke mysql with the -h . option.", part of the
answer is wrong. It states wrongly: "mysql -h . tries to establish a
local connection using shared memory, or, in case this fails, a
named pipe." It should say: "mysql -h . tries to establish a local
connection using named pipes on Windows, if the server has
named-pipe connections enabled. If named-pipe connections
are not enabled, an error occurs."
I think i found some mistakes myself too. It is clear that there is no way of reporting these mistakes anymore, so i've put them here as well.
NOTE: The errata below have not been validated by any of the publishers, mysql or anyone else with some authority; they are my own findings and they might be wrong.
Not a 100% mistake but something worth to
point out i think: The introduction of the book deals with things you
should know before taking an exam and dedicates a special paragraph - on
page 12-13 - about interpreting the DESCRIBE output, since it is essential
for the exam.
On page 13 it is stated that:
If the KEY value is the keyword UNI, this indicates that the column is the
first column of a unique-valued index that cannot contain NULL values.
However it fails to mention that (and i quote the manual here)
Before MySQL 5.0.11, if the column allows NULL values, the Key value can
be MUL even when a single-column UNIQUE index is used. The rationale was
that multiple rows in a UNIQUE index can hold a NULL value if the column
is not declared NOT NULL. As of MySQL 5.0.11, the display is UNI rather
than MUL regardless of whether the column allows NULL; you can see from
the Null field whether or not the column can contain NULL.
Since this section is so important it is already addressed in the
Introduction i think this important information should not be left out. For the exam i think you must assume you're dealing with mysql version >= 5.0.11.
Page 78 (2nd paragraph) it says : 'Define the column that should hold
the updated time with
DEFAULT CURRENT TIMESTAMP'.
DEFAULT should be replaced by
ON UPDATE (which is how the query
below is defined)
Page 88, 2nd bullet: 'A positive value can be inserted explicitly into
AUTO_INCREMENT column if the value isn't already present in the
column.' And also on Page 89, 2nd bullet: 'When you reach the upper limit
AUTO_INCREMENT column, an attempt to generate the next sequence
value results in a duplicate-key error.'
Both statements are wrong, because it's possible (even if it is uncommon)
to define an
AUTO_INCREMENT column with a normal
INDEX (so not
UNIQUE) and in this case you can insert duplicate values and the duplicate
error won't happen. So, the behaviour mentioned in the book isn't
behaviour that can be attributed to the fact that a column is defined as
AUTO_INCREMENT but it is behaviour caused when an column has a
Page 186, 1st bullet. (Not so much a mistake but certainly something worth to point out): 'For positive exact values,
ROUND() rounds up the
next integer if the fractional part is .5 or greater, and down to the next
The book claims to be a certification study guide for mysql 5.0 and in
mysql 5.0 this isn't entirely true. I quote the manual here: "Before MySQL
5.0.3, the behavior of ROUND() when the argument is halfway between two
integers depends on the C library implementation. Different
implementations round to the nearest even number, always up, always down,
or always toward zero."
So, in mysql 5.0.1 for example, the example with ROUND(28.5) on a linux
machine would result in 28 and not 29.
Page 233, As the official errata list (above) mentions: the meaning attributed to the example is wrong.
A quick check will show why it is false: Just delete
all the entries of countries outside the european continent where spanish
is spoken (from the CountryLanguage table) - thereby making the European
continent the only one where Spanish is spoken - and the query will still
return an empty result.
Still on Page 233, another false conclusion is drawn however, which the errata list fails to mention.
"In other words, the statement is really saying 'return all the countries
where there are _some_ people that do not speak Spanish'"
This is also not true, which can be quickly verified by executing this query:
DELETE FROM CountryLanguage
WHERE CountryCode IN ('AND','FRA','ESP','SWE')
AND Language != 'Spanish'
and then running the SELECT query from the book again. Andorra, France,
Spain and Sweden now only have Spanish speakers (so, there not _some_
people that do not speak Spanish - all of them speak spanish now), but
Andorra, France, Spain and Sweden will still show up in the result.
Page 351, last bullet. The first sentence states that Client Programs communicate with the server by sending requests to it over a network connection.
While this is true most of the time, there are other methods too (for local connections), like shared-memory
Page 418, 1st bullet.
Add CREATE TABLE to the list of statements that cause an implicit commit. I've tested this, so i'm quite sure it should've been in the list.
This page lists some statements for table maintenance and indicates for which tables it works. The list of supported tables is incomplete in all cases though.
||Possible message types
||As of MySQL 5.0.16
||status, error, info, or warning
||As of MySQL 5.1.9
||As of MySQL 5.0.16
||status, error, info, note, or warning
||Supported until mysql 5.1. After that support for the whole engine was discontinued
||status, error, info, note, or warning
||status, error, info, note, or warning
||As of MySQL 5.1.9
Page 457, 32.4.1. Add "Output files are written in text format and are portable".
In think this should be added, since it is mentioned explicitly about mysqldump (32.4.2, page 458) and the same is true for
SELECT INTO OUTFILE
Page 457, 32.4.2. This chapter fails to mention that mysqldump doesn't backup your stored routines in version prior to 5.1.2. After reading 32.5 (page 461) it seems that when you perform these actions together you will have a complete backup, but - as i said - this is not true in versions < 5.1.2; here you should manually back up your stored routines as well. A possibility is to make a backup of the mysql.proc table.