SQL - Revision history

DavidB4: a little choppy, but improved

2017-03-09T17:57:25Z

a little choppy, but improved

DavidB4: added an extended example

2017-03-09T15:14:20Z

added an extended example

DavidB4-bot: /* References */clean up

2016-06-23T15:06:10Z

References: clean up

JlHawkwell: added examples

2010-08-03T00:04:32Z

added examples

Tuffskin at 13:00, December 22, 2009

2009-12-22T13:00:09Z

Tuffskin at 12:55, December 22, 2009

2009-12-22T12:55:55Z

Learn together: Category

2008-06-03T16:12:38Z

Learn together: Merged in information from recently created "Structured Query Language" article

2007-10-25T17:15:00Z

Merged in information from recently created "Structured Query Language" article

Aschlafly at 16:41, July 12, 2007

2007-07-12T16:41:31Z

Aschlafly at 16:41, July 12, 2007

2007-07-12T16:41:12Z

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-'''SQL''', which stands for "Structured Query Language" is a [[computer language]] for [[relational database]] systems. It was first developed by EF Codd at [[IBM]].
+'''SQL''', which stands for "Structured Query Language" is a [[computer language]] for [[relational database]] systems. It was first developed by EF Codd at [[IBM]]. In 1986 the American National Standards Institute ([[ANSI]]) promulgated standards for SQL, and since then revisions have been approved by the International Organization for Standardization ([[ISO]]). SQL was immensely successful, and is supported by a number of database systems, including [[MySQL]].  MySQL is one of the two databases supported by [[MediaWiki]] (the other being PostgreSQL),<ref>http://www.mediawiki.org/wiki/Manual:LocalSettings.php#Database_settings</ref> the software behind a number of wiki-based systems, including Conservapedia.
 == Transactions ==
 A transaction may include several SQL statements, and the sequence of statements are executed [[atomically]]. The transaction represents a logical unit work such as a customer purchasing a product. For example, the statements may include adding the purchase price to the customer's account, and subtracting the product from inventory. If either statement is executed, they must both be executed, and if either statement is aborted, they must both be aborted. This is achieved by using the COMMIT statement and the ROLLBACK statement. Once all of the statements to execute for the current transaction have been entered, the COMMIT statement is entered, and the transaction is committed to the database. If any of the statements in the transaction cannot be completed, the entire transaction is rolled back, and none of the statements take effect.

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 Whoever customer 15 is, their account has just been deleted.
 ==References==
 <references/>
 [[Category:Programming Languages]]

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−	[[~~category~~:Programming Languages]]	+	[[Category:Programming Languages]]

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	Transactions exhibit their own properties such as an [[isolation level]]. The transaction [[isolation level]] determines the level of interactivity with other concurrently running transactions. By default each transaction is conceptually isolated from all other transactions, thereby preventing two (or more) transactions from concurrently reading and/or updating the same data records.		Transactions exhibit their own properties such as an [[isolation level]]. The transaction [[isolation level]] determines the level of interactivity with other concurrently running transactions. By default each transaction is conceptually isolated from all other transactions, thereby preventing two (or more) transactions from concurrently reading and/or updating the same data records.
		+
		+	== Example Queries ==
		+	SQL statements come in many forms, but the most common types are SELECT, INSERT, and UPDATE. DELETE is also used, but far less frequently.
		+
		+	<pre>SELECT * FROM customer_data WHERE customer_id = 5;</pre>
		+	This would be used by an application to read information about a specific customer.
		+
		+	<pre>UPDATE customer_data SET customer_firstname = 'Joe' WHERE customer_id = 5;</pre>
		+	This statement simply sets the name of customer 5 to be Joe.
		+
		+	<pre>INSERT customer_data (customer_name, customer_username, customer_password) VALUES ('Mary', 'Mary7', MD5('password'));</pre>
		+	Adding a new customer named Mary. Her password is MD5 hashed for security purposes.
		+
		+	<pre>DELETE FROM customer_data WHERE customer_id = 15;</pre>
		+	Whoever customer 15 is, their account has just been deleted.

	==References==		==References==

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 == Transactions ==
-A transaction may include several SQL statements, but the statements are processed in an all-or-nothing fashion. The transaction represents logical work like a customer purchasing a product. For example, the statements may include adding the purchase price to the customer's account, and subtracting the product from inventory. If either statement is executed, they must both be executed, and if either statement is aborted, they must both be aborted. This is achieved by using the COMMIT statement and the ROLLBACK statement. Once all of the statements to execute for the current transaction have been entered, the COMMIT statement is entered, and the transaction is committed to the database. If any of the statements in the transaction cannot be completed, the entire transaction is rolled back, and none of the statements take effect.
+A transaction may include several SQL statements, and the sequence of statements are executed [[atomically]]. The transaction represents a logical unit work such as a customer purchasing a product. For example, the statements may include adding the purchase price to the customer's account, and subtracting the product from inventory. If either statement is executed, they must both be executed, and if either statement is aborted, they must both be aborted. This is achieved by using the COMMIT statement and the ROLLBACK statement. Once all of the statements to execute for the current transaction have been entered, the COMMIT statement is entered, and the transaction is committed to the database. If any of the statements in the transaction cannot be completed, the entire transaction is rolled back, and none of the statements take effect.
 ==References==

← Older revision		Revision as of 12:55, December 22, 2009
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−	'''SQL''', which stands for "Structured Query Language," is a [[computer language]] for [[relational database]] systems. It was first developed by EF Codd at [[IBM]].	+	'''SQL''', which stands for "Structured Query Language" is a [[computer language]] for [[relational database]] systems. It was first developed by EF Codd at [[IBM]].

	In 1986 the American National Standards Institute ([[ANSI]]) promulgated standards for SQL, and since then revisions have been approved by the International Organization for Standardization ([[ISO]]).		In 1986 the American National Standards Institute ([[ANSI]]) promulgated standards for SQL, and since then revisions have been approved by the International Organization for Standardization ([[ISO]]).

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	<references/>		<references/>

−	[[category:~~software~~]]	+	[[category:Programming Languages]]

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 In 1986 the American National Standards Institute ([[ANSI]]) promulgated standards for SQL, and since then revisions have been approved by the International Organization for Standardization ([[ISO]]).
-SQL was immensely successful, and is supported by a number of database systems, including [[MySQL]].  MySQL is one of the two databases supported by [[MediaWiki]] (the other being PostgreSQL)<ref>http://www.mediawiki.org/wiki/Manual:LocalSettings.php#Database_settings</ref>[[MediaWiki]], the software behind a number of wiki-based systems.
+SQL was immensely successful, and is supported by a number of database systems, including [[MySQL]].  MySQL is one of the two databases supported by [[MediaWiki]] (the other being PostgreSQL),<ref>http://www.mediawiki.org/wiki/Manual:LocalSettings.php#Database_settings</ref> the software behind a number of wiki-based systems.
 ==References==