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Cleanup of MySQL-Max description 


Docs/manual.texi:
  Moved things in example section.
  Added some links from user comments.
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Docs/manual.texi
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......@@ -538,29 +538,18 @@ MySQL Tutorial
* Connecting-disconnecting:: Connecting to and disconnecting from the server
* Entering queries:: Entering queries
* Examples:: Examples
* Searching on two keys:: Searching on two keys
* Database use:: Creating and using a database
* Getting information:: Getting information about databases and tables
* Examples:: Examples
* Batch mode:: Using @code{mysql} in batch mode
* Twin:: Queries from twin project
Examples of Common Queries
* example-Maximum-column:: The maximum value for a column
* example-Maximum-row:: The row holding the maximum of a certain column
* example-Maximum-column-group:: Maximum of column per group
* example-Maximum-column-group-row:: The rows holding the group-wise maximum of a certain field
* example-user-variables:: Using user variables
* example-Foreign keys:: Using foreign keys
Creating and Using a Database
* Creating database:: Creating a database
* Creating tables:: Creating a table
* Loading tables:: Loading data into a table
* Retrieving data:: Retrieving information from a table
* Multiple tables:: Using more than one table
Retrieving Information from a Table
......@@ -572,6 +561,17 @@ Retrieving Information from a Table
* Working with NULL:: Working with @code{NULL} values
* Pattern matching:: Pattern matching
* Counting rows:: Counting rows
* Multiple tables::
Examples of Common Queries
* example-Maximum-column:: The maximum value for a column
* example-Maximum-row:: The row holding the maximum of a certain column
* example-Maximum-column-group:: Maximum of column per group
* example-Maximum-column-group-row:: The rows holding the group-wise maximum of a certain field
* example-user-variables:: Using user variables
* example-Foreign keys:: Using foreign keys
* Searching on two keys::
Queries from Twin Project
......@@ -2486,8 +2486,14 @@ which services were discovered on which dial-up numbers in your organization.
@subheading SQL Clients and Report Writers
@table @asis
@item @uref{http://www.urbanresearch.com/software/utils/urbsql/index.html}
@strong{MySQL} Editor/Utility for MS Windows Platforms.
@item @uref{http://www.urbanresearch.com/software/utils/urbsql/index.html, urSQL}
SQL Editor and Query Utility. Custom syntax highlighting, editable
results grid, exportable result-sets, basic @strong{MySQL} admin functions,
Etc.. For windows.
@item @uref{http://www.edatanew.com/, MySQL Data Manager}
@strong{MySQL} Data Manager * is platform independent web client
(written in perl) for @strong{MySQL} server over TCP/IP.
@item @uref{http://ksql.sourceforge.net/}
KDE @strong{MySQL} client.
......@@ -24429,10 +24435,9 @@ Innodb table space will not be reclaimed.
@menu
* Connecting-disconnecting:: Connecting to and disconnecting from the server
* Entering queries:: Entering queries
* Examples:: Examples
* Searching on two keys:: Searching on two keys
* Database use:: Creating and using a database
* Getting information:: Getting information about databases and tables
* Examples:: Examples
* Batch mode:: Using @code{mysql} in batch mode
* Twin:: Queries from twin project
@end menu
......@@ -24532,7 +24537,7 @@ server. They indicate this by the @code{mysql>} prompt.
@cindex running, queries
@cindex queries, entering
@cindex entering, queries
@node Entering queries, Examples, Connecting-disconnecting, Tutorial
@node Entering queries, Database use, Connecting-disconnecting, Tutorial
@section Entering Queries
Make sure you are connected to the server, as discussed in the previous
......@@ -24754,358 +24759,10 @@ containing @code{QUIT}! This can be quite confusing, especially if you
don't know that you need to supply the terminating quote before you can
cancel the current command.
@cindex queries, examples
@cindex examples, queries
@node Examples, Searching on two keys, Entering queries, Tutorial
@section Examples of Common Queries
Here are examples of how to solve some common problems with
@strong{MySQL}.
Some of the examples use the table @code{shop} to hold the price of each
article (item number) for certain traders (dealers). Supposing that each
trader has a single fixed price per article, then (@code{item},
@code{trader}) is a primary key for the records.
Start the command line tool @code{mysql} and select a database:
@example
mysql your-database-name
@end example
(In most @strong{MySQL} installations, you can use the database-name 'test').
You can create the example table as:
@example
CREATE TABLE shop (
article INT(4) UNSIGNED ZEROFILL DEFAULT '0000' NOT NULL,
dealer CHAR(20) DEFAULT '' NOT NULL,
price DOUBLE(16,2) DEFAULT '0.00' NOT NULL,
PRIMARY KEY(article, dealer));
INSERT INTO shop VALUES
(1,'A',3.45),(1,'B',3.99),(2,'A',10.99),(3,'B',1.45),(3,'C',1.69),
(3,'D',1.25),(4,'D',19.95);
@end example
Okay, so the example data is:
@example
mysql> SELECT * FROM shop;
+---------+--------+-------+
| article | dealer | price |
+---------+--------+-------+
| 0001 | A | 3.45 |
| 0001 | B | 3.99 |
| 0002 | A | 10.99 |
| 0003 | B | 1.45 |
| 0003 | C | 1.69 |
| 0003 | D | 1.25 |
| 0004 | D | 19.95 |
+---------+--------+-------+
@end example
@menu
* example-Maximum-column:: The maximum value for a column
* example-Maximum-row:: The row holding the maximum of a certain column
* example-Maximum-column-group:: Maximum of column per group
* example-Maximum-column-group-row:: The rows holding the group-wise maximum of a certain field
* example-user-variables:: Using user variables
* example-Foreign keys:: Using foreign keys
@end menu
@node example-Maximum-column, example-Maximum-row, Examples, Examples
@subsection The Maximum Value for a Column
``What's the highest item number?''
@example
SELECT MAX(article) AS article FROM shop
+---------+
| article |
+---------+
| 4 |
+---------+
@end example
@node example-Maximum-row, example-Maximum-column-group, example-Maximum-column, Examples
@subsection The Row Holding the Maximum of a Certain Column
``Find number, dealer, and price of the most expensive article.''
In ANSI SQL this is easily done with a sub-query:
@example
SELECT article, dealer, price
FROM shop
WHERE price=(SELECT MAX(price) FROM shop)
@end example
In @strong{MySQL} (which does not yet have sub-selects), just do it in
two steps:
@enumerate
@item
Get the maximum price value from the table with a @code{SELECT} statement.
@item
Using this value compile the actual query:
@example
SELECT article, dealer, price
FROM shop
WHERE price=19.95
@end example
@end enumerate
Another solution is to sort all rows descending by price and only
get the first row using the @strong{MySQL} specific @code{LIMIT} clause:
@example
SELECT article, dealer, price
FROM shop
ORDER BY price DESC
LIMIT 1
@end example
@strong{NOTE}: If there are several most expensive articles (for example, each 19.95)
the @code{LIMIT} solution shows only one of them!
@node example-Maximum-column-group, example-Maximum-column-group-row, example-Maximum-row, Examples
@subsection Maximum of Column per Group
``What's the highest price per article?''
@example
SELECT article, MAX(price) AS price
FROM shop
GROUP BY article
+---------+-------+
| article | price |
+---------+-------+
| 0001 | 3.99 |
| 0002 | 10.99 |
| 0003 | 1.69 |
| 0004 | 19.95 |
+---------+-------+
@end example
@node example-Maximum-column-group-row, example-user-variables, example-Maximum-column-group, Examples
@subsection The Rows Holding the Group-wise Maximum of a Certain Field
``For each article, find the dealer(s) with the most expensive price.''
In ANSI SQL, I'd do it with a sub-query like this:
@example
SELECT article, dealer, price
FROM shop s1
WHERE price=(SELECT MAX(s2.price)
FROM shop s2
WHERE s1.article = s2.article);
@end example
In @strong{MySQL} it's best do it in several steps:
@enumerate
@item
Get the list of (article,maxprice).
@item
For each article get the corresponding rows that have the stored maximum
price.
@end enumerate
This can easily be done with a temporary table:
@example
CREATE TEMPORARY TABLE tmp (
article INT(4) UNSIGNED ZEROFILL DEFAULT '0000' NOT NULL,
price DOUBLE(16,2) DEFAULT '0.00' NOT NULL);
LOCK TABLES shop read;
INSERT INTO tmp SELECT article, MAX(price) FROM shop GROUP BY article;
SELECT shop.article, dealer, shop.price FROM shop, tmp
WHERE shop.article=tmp.article AND shop.price=tmp.price;
UNLOCK TABLES;
DROP TABLE tmp;
@end example
If you don't use a @code{TEMPORARY} table, you must also lock the 'tmp' table.
``Can it be done with a single query?''
Yes, but only by using a quite inefficient trick that I call the
``MAX-CONCAT trick'':
@example
SELECT article,
SUBSTRING( MAX( CONCAT(LPAD(price,6,'0'),dealer) ), 7) AS dealer,
0.00+LEFT( MAX( CONCAT(LPAD(price,6,'0'),dealer) ), 6) AS price
FROM shop
GROUP BY article;
+---------+--------+-------+
| article | dealer | price |
+---------+--------+-------+
| 0001 | B | 3.99 |
| 0002 | A | 10.99 |
| 0003 | C | 1.69 |
| 0004 | D | 19.95 |
+---------+--------+-------+
@end example
The last example can, of course, be made a bit more efficient by doing the
splitting of the concatenated column in the client.
@node example-user-variables, example-Foreign keys, example-Maximum-column-group-row, Examples
@subsection Using user variables
You can use @strong{MySQL} user variables to remember results without
having to store them in a temporary variables in the client.
@xref{Variables}.
For example, to find the articles with the highest and lowest price you
can do:
@example
select @@min_price:=min(price),@@max_price:=max(price) from shop;
select * from shop where price=@@min_price or price=@@max_price;
+---------+--------+-------+
| article | dealer | price |
+---------+--------+-------+
| 0003 | D | 1.25 |
| 0004 | D | 19.95 |
+---------+--------+-------+
@end example
@cindex foreign keys
@cindex keys, foreign
@node example-Foreign keys, , example-user-variables, Examples
@subsection Using Foreign Keys
You don't need foreign keys to join 2 tables.
The only thing @strong{MySQL} doesn't do is @code{CHECK} to make sure that
the keys you use really exist in the table(s) you're referencing and it
doesn't automatically delete rows from table with a foreign key
definition. If you use your keys like normal, it'll work just fine:
@example
CREATE TABLE persons (
id SMALLINT UNSIGNED NOT NULL AUTO_INCREMENT,
name CHAR(60) NOT NULL,
PRIMARY KEY (id)
);
CREATE TABLE shirts (
id SMALLINT UNSIGNED NOT NULL AUTO_INCREMENT,
style ENUM('t-shirt', 'polo', 'dress') NOT NULL,
color ENUM('red', 'blue', 'orange', 'white', 'black') NOT NULL,
owner SMALLINT UNSIGNED NOT NULL REFERENCES persons,
PRIMARY KEY (id)
);
INSERT INTO persons VALUES (NULL, 'Antonio Paz');
INSERT INTO shirts VALUES
(NULL, 'polo', 'blue', LAST_INSERT_ID()),
(NULL, 'dress', 'white', LAST_INSERT_ID()),
(NULL, 't-shirt', 'blue', LAST_INSERT_ID());
INSERT INTO persons VALUES (NULL, 'Lilliana Angelovska');
INSERT INTO shirts VALUES
(NULL, 'dress', 'orange', LAST_INSERT_ID()),
(NULL, 'polo', 'red', LAST_INSERT_ID()),
(NULL, 'dress', 'blue', LAST_INSERT_ID()),
(NULL, 't-shirt', 'white', LAST_INSERT_ID());
SELECT * FROM persons;
+----+---------------------+
| id | name |
+----+---------------------+
| 1 | Antonio Paz |
| 2 | Lilliana Angelovska |
+----+---------------------+
SELECT * FROM shirts;
+----+---------+--------+-------+
| id | style | color | owner |
+----+---------+--------+-------+
| 1 | polo | blue | 1 |
| 2 | dress | white | 1 |
| 3 | t-shirt | blue | 1 |
| 4 | dress | orange | 2 |
| 5 | polo | red | 2 |
| 6 | dress | blue | 2 |
| 7 | t-shirt | white | 2 |
+----+---------+--------+-------+
SELECT s.* FROM persons p, shirts s
WHERE p.name LIKE 'Lilliana%'
AND s.owner = p.id
AND s.color <> 'white';
+----+-------+--------+-------+
| id | style | color | owner |
+----+-------+--------+-------+
| 4 | dress | orange | 2 |
| 5 | polo | red | 2 |
| 6 | dress | blue | 2 |
+----+-------+--------+-------+
@end example
@findex UNION
@cindex searching, two keys
@cindex keys, searching on two
@node Searching on two keys, Database use, Examples, Tutorial
@section Searching on Two Keys
@strong{MySQL} doesn't yet optimize when you search on two different
keys combined with @code{OR} (Searching on one key with different @code{OR}
parts is optimized quite good):
@example
SELECT field1_index, field2_index FROM test_table WHERE field1_index = '1'
OR field2_index = '1'
@end example
The reason is that we haven't yet had time to come up with an efficient
way to handle this in the general case. (The @code{AND} handling is,
in comparison, now completely general and works very well).
For the moment you can solve this very efficiently by using a
@code{TEMPORARY} table. This type of optimization is also very good if
you are using very complicated queries where the SQL server does the
optimizations in the wrong order.
@example
CREATE TEMPORARY TABLE tmp
SELECT field1_index, field2_index FROM test_table WHERE field1_index = '1';
INSERT INTO tmp
SELECT field1_index, field2_index FROM test_table WHERE field2_index = '1';
SELECT * from tmp;
DROP TABLE tmp;
@end example
The above way to solve this query is in effect an @code{UNION} of two queries.
@cindex databases, creating
@cindex databases, using
@cindex creating, databases
@node Database use, Getting information, Searching on two keys, Tutorial
@node Database use, Getting information, Entering queries, Tutorial
@section Creating and Using a Database
@menu
......@@ -25113,7 +24770,6 @@ The above way to solve this query is in effect an @code{UNION} of two queries.
* Creating tables:: Creating a table
* Loading tables:: Loading data into a table
* Retrieving data:: Retrieving information from a table
* Multiple tables:: Using more than one table
@end menu
Now that you know how to enter commands, it's time to access a database.
......@@ -25416,7 +25072,7 @@ than a single @code{LOAD DATA} statement.
@cindex tables, retrieving data
@cindex retrieving, data from tables
@cindex unloading, tables
@node Retrieving data, Multiple tables, Loading tables, Database use
@node Retrieving data, , Loading tables, Database use
@subsection Retrieving Information from a Table
@menu
......@@ -25428,6 +25084,7 @@ than a single @code{LOAD DATA} statement.
* Working with NULL:: Working with @code{NULL} values
* Pattern matching:: Pattern matching
* Counting rows:: Counting rows
* Multiple tables::
@end menu
The @code{SELECT} statement is used to pull information from a table.
......@@ -26150,7 +25807,7 @@ mysql> SELECT * FROM pet WHERE name REGEXP "^.@{5@}$";
@cindex rows, counting
@cindex tables, counting rows
@cindex counting, table rows
@node Counting rows, , Pattern matching, Retrieving data
@node Counting rows, Multiple tables, Pattern matching, Retrieving data
@subsubsection Counting Rows
Databases are often used to answer the question, ``How often does a certain
......@@ -26286,8 +25943,8 @@ mysql> SELECT species, sex, COUNT(*) FROM pet
@end example
@cindex tables, multiple
@node Multiple tables, , Retrieving data, Database use
@subsection Using More Than one Table
@node Multiple tables, , Counting rows, Retrieving data
@subsubsection Using More Than one Table
The @code{pet} table keeps track of which pets you have. If you want to
record other information about them, such as events in their lives like
......@@ -26408,7 +26065,7 @@ each column reference is associated with.
@cindex databases, information about
@cindex tables, information about
@findex DESCRIBE
@node Getting information, Batch mode, Database use, Tutorial
@node Getting information, Examples, Database use, Tutorial
@section Getting Information About Databases and Tables
What if you forget the name of a database or table, or what the structure of
......@@ -26469,12 +26126,361 @@ indexed, and @code{Default} specifies the column's default value.
If you have indexes on a table,
@code{SHOW INDEX FROM tbl_name} produces information about them.
@cindex queries, examples
@cindex examples, queries
@node Examples, Batch mode, Getting information, Tutorial
@section Examples of Common Queries
Here are examples of how to solve some common problems with
@strong{MySQL}.
Some of the examples use the table @code{shop} to hold the price of each
article (item number) for certain traders (dealers). Supposing that each
trader has a single fixed price per article, then (@code{item},
@code{trader}) is a primary key for the records.
Start the command line tool @code{mysql} and select a database:
@example
mysql your-database-name
@end example
(In most @strong{MySQL} installations, you can use the database-name 'test').
You can create the example table as:
@example
CREATE TABLE shop (
article INT(4) UNSIGNED ZEROFILL DEFAULT '0000' NOT NULL,
dealer CHAR(20) DEFAULT '' NOT NULL,
price DOUBLE(16,2) DEFAULT '0.00' NOT NULL,
PRIMARY KEY(article, dealer));
INSERT INTO shop VALUES
(1,'A',3.45),(1,'B',3.99),(2,'A',10.99),(3,'B',1.45),(3,'C',1.69),
(3,'D',1.25),(4,'D',19.95);
@end example
Okay, so the example data is:
@example
mysql> SELECT * FROM shop;
+---------+--------+-------+
| article | dealer | price |
+---------+--------+-------+
| 0001 | A | 3.45 |
| 0001 | B | 3.99 |
| 0002 | A | 10.99 |
| 0003 | B | 1.45 |
| 0003 | C | 1.69 |
| 0003 | D | 1.25 |
| 0004 | D | 19.95 |
+---------+--------+-------+
@end example
@menu
* example-Maximum-column:: The maximum value for a column
* example-Maximum-row:: The row holding the maximum of a certain column
* example-Maximum-column-group:: Maximum of column per group
* example-Maximum-column-group-row:: The rows holding the group-wise maximum of a certain field
* example-user-variables:: Using user variables
* example-Foreign keys:: Using foreign keys
* Searching on two keys::
@end menu
@node example-Maximum-column, example-Maximum-row, Examples, Examples
@subsection The Maximum Value for a Column
``What's the highest item number?''
@example
SELECT MAX(article) AS article FROM shop
+---------+
| article |
+---------+
| 4 |
+---------+
@end example
@node example-Maximum-row, example-Maximum-column-group, example-Maximum-column, Examples
@subsection The Row Holding the Maximum of a Certain Column
``Find number, dealer, and price of the most expensive article.''
In ANSI SQL this is easily done with a sub-query:
@example
SELECT article, dealer, price
FROM shop
WHERE price=(SELECT MAX(price) FROM shop)
@end example
In @strong{MySQL} (which does not yet have sub-selects), just do it in
two steps:
@enumerate
@item
Get the maximum price value from the table with a @code{SELECT} statement.
@item
Using this value compile the actual query:
@example
SELECT article, dealer, price
FROM shop
WHERE price=19.95
@end example
@end enumerate
Another solution is to sort all rows descending by price and only
get the first row using the @strong{MySQL} specific @code{LIMIT} clause:
@example
SELECT article, dealer, price
FROM shop
ORDER BY price DESC
LIMIT 1
@end example
@strong{NOTE}: If there are several most expensive articles (for example, each 19.95)
the @code{LIMIT} solution shows only one of them!
@node example-Maximum-column-group, example-Maximum-column-group-row, example-Maximum-row, Examples
@subsection Maximum of Column per Group
``What's the highest price per article?''
@example
SELECT article, MAX(price) AS price
FROM shop
GROUP BY article
+---------+-------+
| article | price |
+---------+-------+
| 0001 | 3.99 |
| 0002 | 10.99 |
| 0003 | 1.69 |
| 0004 | 19.95 |
+---------+-------+
@end example
@node example-Maximum-column-group-row, example-user-variables, example-Maximum-column-group, Examples
@subsection The Rows Holding the Group-wise Maximum of a Certain Field
``For each article, find the dealer(s) with the most expensive price.''
In ANSI SQL, I'd do it with a sub-query like this:
@example
SELECT article, dealer, price
FROM shop s1
WHERE price=(SELECT MAX(s2.price)
FROM shop s2
WHERE s1.article = s2.article);
@end example
In @strong{MySQL} it's best do it in several steps:
@enumerate
@item
Get the list of (article,maxprice).
@item
For each article get the corresponding rows that have the stored maximum
price.
@end enumerate
This can easily be done with a temporary table:
@example
CREATE TEMPORARY TABLE tmp (
article INT(4) UNSIGNED ZEROFILL DEFAULT '0000' NOT NULL,
price DOUBLE(16,2) DEFAULT '0.00' NOT NULL);
LOCK TABLES shop read;
INSERT INTO tmp SELECT article, MAX(price) FROM shop GROUP BY article;
SELECT shop.article, dealer, shop.price FROM shop, tmp
WHERE shop.article=tmp.article AND shop.price=tmp.price;
UNLOCK TABLES;
DROP TABLE tmp;
@end example
If you don't use a @code{TEMPORARY} table, you must also lock the 'tmp' table.
``Can it be done with a single query?''
Yes, but only by using a quite inefficient trick that I call the
``MAX-CONCAT trick'':
@example
SELECT article,
SUBSTRING( MAX( CONCAT(LPAD(price,6,'0'),dealer) ), 7) AS dealer,
0.00+LEFT( MAX( CONCAT(LPAD(price,6,'0'),dealer) ), 6) AS price
FROM shop
GROUP BY article;
+---------+--------+-------+
| article | dealer | price |
+---------+--------+-------+
| 0001 | B | 3.99 |
| 0002 | A | 10.99 |
| 0003 | C | 1.69 |
| 0004 | D | 19.95 |
+---------+--------+-------+
@end example
The last example can, of course, be made a bit more efficient by doing the
splitting of the concatenated column in the client.
@node example-user-variables, example-Foreign keys, example-Maximum-column-group-row, Examples
@subsection Using user variables
You can use @strong{MySQL} user variables to remember results without
having to store them in a temporary variables in the client.
@xref{Variables}.
For example, to find the articles with the highest and lowest price you
can do:
@example
select @@min_price:=min(price),@@max_price:=max(price) from shop;
select * from shop where price=@@min_price or price=@@max_price;
+---------+--------+-------+
| article | dealer | price |
+---------+--------+-------+
| 0003 | D | 1.25 |
| 0004 | D | 19.95 |
+---------+--------+-------+
@end example
@cindex foreign keys
@cindex keys, foreign
@node example-Foreign keys, Searching on two keys, example-user-variables, Examples
@subsection Using Foreign Keys
You don't need foreign keys to join 2 tables.
The only thing @strong{MySQL} doesn't do is @code{CHECK} to make sure that
the keys you use really exist in the table(s) you're referencing and it
doesn't automatically delete rows from table with a foreign key
definition. If you use your keys like normal, it'll work just fine:
@example
CREATE TABLE persons (
id SMALLINT UNSIGNED NOT NULL AUTO_INCREMENT,
name CHAR(60) NOT NULL,
PRIMARY KEY (id)
);
CREATE TABLE shirts (
id SMALLINT UNSIGNED NOT NULL AUTO_INCREMENT,
style ENUM('t-shirt', 'polo', 'dress') NOT NULL,
color ENUM('red', 'blue', 'orange', 'white', 'black') NOT NULL,
owner SMALLINT UNSIGNED NOT NULL REFERENCES persons,
PRIMARY KEY (id)
);
INSERT INTO persons VALUES (NULL, 'Antonio Paz');
INSERT INTO shirts VALUES
(NULL, 'polo', 'blue', LAST_INSERT_ID()),
(NULL, 'dress', 'white', LAST_INSERT_ID()),
(NULL, 't-shirt', 'blue', LAST_INSERT_ID());
INSERT INTO persons VALUES (NULL, 'Lilliana Angelovska');
INSERT INTO shirts VALUES
(NULL, 'dress', 'orange', LAST_INSERT_ID()),
(NULL, 'polo', 'red', LAST_INSERT_ID()),
(NULL, 'dress', 'blue', LAST_INSERT_ID()),
(NULL, 't-shirt', 'white', LAST_INSERT_ID());
SELECT * FROM persons;
+----+---------------------+
| id | name |
+----+---------------------+
| 1 | Antonio Paz |
| 2 | Lilliana Angelovska |
+----+---------------------+
SELECT * FROM shirts;
+----+---------+--------+-------+
| id | style | color | owner |
+----+---------+--------+-------+
| 1 | polo | blue | 1 |
| 2 | dress | white | 1 |
| 3 | t-shirt | blue | 1 |
| 4 | dress | orange | 2 |
| 5 | polo | red | 2 |
| 6 | dress | blue | 2 |
| 7 | t-shirt | white | 2 |
+----+---------+--------+-------+
SELECT s.* FROM persons p, shirts s
WHERE p.name LIKE 'Lilliana%'
AND s.owner = p.id
AND s.color <> 'white';
+----+-------+--------+-------+
| id | style | color | owner |
+----+-------+--------+-------+
| 4 | dress | orange | 2 |
| 5 | polo | red | 2 |
| 6 | dress | blue | 2 |
+----+-------+--------+-------+
@end example
@findex UNION
@cindex searching, two keys
@cindex keys, searching on two
@node Searching on two keys, , example-Foreign keys, Examples
@subsection Searching on Two Keys
@strong{MySQL} doesn't yet optimize when you search on two different
keys combined with @code{OR} (Searching on one key with different @code{OR}
parts is optimized quite good):
@example
SELECT field1_index, field2_index FROM test_table WHERE field1_index = '1'
OR field2_index = '1'
@end example
The reason is that we haven't yet had time to come up with an efficient
way to handle this in the general case. (The @code{AND} handling is,
in comparison, now completely general and works very well).
For the moment you can solve this very efficiently by using a
@code{TEMPORARY} table. This type of optimization is also very good if
you are using very complicated queries where the SQL server does the
optimizations in the wrong order.
@example
CREATE TEMPORARY TABLE tmp
SELECT field1_index, field2_index FROM test_table WHERE field1_index = '1';
INSERT INTO tmp
SELECT field1_index, field2_index FROM test_table WHERE field2_index = '1';
SELECT * from tmp;
DROP TABLE tmp;
@end example
The above way to solve this query is in effect an @code{UNION} of two queries.
@cindex modes, batch
@cindex batch mode
@cindex running, batch mode
@cindex script files
@cindex files, script
@node Batch mode, Twin, Getting information, Tutorial
@node Batch mode, Twin, Examples, Tutorial
@section Using @code{mysql} in Batch Mode
In the previous sections, you used @code{mysql} interactively to enter
......@@ -41240,6 +41246,10 @@ An online magazine featuring music, literature, arts, and design content.
@itemize @bullet
@item @uref{http://liftoff.msfc.nasa.gov, NASA}
@item @uref{http://kids.msfc.nasa.gov, NASA KIDS}
@item @uref{http://science.nasa.gov, Sience@@NASA}
@item @uref{http://lindev.jmc.tju.edu/qwor, Qt Widget and Object Repository}
@item @uref{http://www.samba-choro.com.br, Brazilian samba site (in Portuguese)}
......@@ -42108,6 +42118,10 @@ An authentication module for the Cyrus IMAP server. By Aaron Newsome.
@appendixsec Converters
@itemize @bullet
item @uref{http://www.mysql.com/Downloads/Contrib/mssql2mysql.txt, mssql2mysql.txt}
Converter from MS-SQL to MySQL. By Michael Kofler.
@uref{http://www.kofler.cc/mysql/mssql2mysql.html, mssql2mysql home page}.
@item @uref{http://www.mysql.com/Downloads/Contrib/dbf2mysql-1.14.tar.gz, dbf2mysql-1.14.tar.gz}
Convert between @file{.dbf} files and @strong{MySQL} tables. By Maarten
Boekhold (@email{boekhold@@cindy.et.tudelft.nl}), William Volkman, and
support-files/mysql.spec.sh
View file @ cd260ea6
......@@ -17,6 +17,7 @@ Source: http://www.mysql.com/Downloads/MySQL-@MYSQL_BASE_VERSION@/mysql-%{mysql
Icon: mysql.gif
URL: http://www.mysql.com/
Packager: David Axmark <david@mysql.com>
Vendor: MySQL AB
Provides: msqlormysql MySQL-server
Obsoletes: mysql
......@@ -133,10 +134,10 @@ Summary: MySQL - server with Berkeley DB and Innodb support
Group: Applications/Databases
Obsoletes: mysql-Max
%description Max
Extra MySQL server binary to get support extra features like
transactional tables. To active these features on only have to install
this package after the server package.
%description Max
Optional MySQL server binary that supports features
like transactional tables. To active this binary, just install this
package after the MySQL package.
%prep
%setup -n mysql-%{mysql_version}
......
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