Java Database Connectivity: Difference between revisions

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{{Short description|API for Java}}

'''Java Database Connectivity''' ('''JDBC''') is an [[application programming interface]] (API) for the programming language [[Java (programming language)|Java]], programming language which defines how a client may access a [[database]]. It is a Java-based data access technology used for Java database connectivity. It is part of the [[Java Standard Edition]] platform, from [[Oracle Corporation]]. It provides methods to query and update data in a database, and is oriented toward [[relationalRelational database|relational databases]]s. A JDBC-to-[[ODBC]] bridge enables connections to any ODBC-accessible data source in the [[Java virtual machine]] (JVM) host environment.{{Infobox software

{{Infobox software

|name = JDBC

|logo =

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|website = {{Javadoc:SE-guide|jdbc|JDBC API Guide}}

}}

'''Java Database Connectivity''' ('''JDBC''') is an [[application programming interface]] (API) for the programming language [[Java (programming language)|Java]], which defines how a client may access a [[database]]. It is a Java-based data access technology used for Java database connectivity. It is part of the [[Java Standard Edition]] platform, from [[Oracle Corporation]]. It provides methods to query and update data in a database, and is oriented toward [[relational database]]s. A JDBC-to-[[ODBC]] bridge enables connections to any ODBC-accessible data source in the [[Java virtual machine]] (JVM) host environment.

==History and implementation==

[[Sun Microsystems]] released JDBC as part of [[Java Development Kit]] (JDK) 1.1 on February 19, 1997.<ref name="JDK 1.1 release">

{{cite web

| title = Sun Ships JDK 1.1 -- Javabeans Included

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Since then it has been part of the [[Java Platform, Standard Edition]] (Java SE).

The JDBC classes are contained in the [[Java package]] {{Javadoc:SE|package=java.sql|java/sql|module=java.sql}} and {{Javadoc:SE|package=javax.sql|javax/sql|module=java.sql}}, as well as a few other classes elsewhere. Everything involved in JDBC is exported through [[Java Platform Module System|module]] <code>java.sql</code>.

Starting with version 3.1, JDBC has been developed under the [[Java Community Process]]. JSR 54 specifies JDBC 3.0 (included in J2SE 1.4), JSR 114 specifies the JDBC Rowset additions, and JSR 221 is the specification of JDBC 4.0 (included in Java SE 6).<ref>[http://java.sun.com/products/jdbc/download.html#corespec40 JDBC API Specification Version: 4.0].</ref>

JDBC 4.1, is specified by a maintenance release 1 of JSR 221<ref>{{cite web|url=http://jcp.org/aboutJava/communityprocess/mrel/jsr221/index.html|title=The Java Community Process(SM) Program - communityprocess - mrel|website=jcp.org|access-date=22 March 2018}}</ref> and is included in Java SE 7.<ref>{{cite web|url=http://docs.oracle.com/javase/7/docs/technotes/guides/jdbc/jdbc_41.html|title=JDBC 4.1|website=docs.oracle.com|access-date=22 March 2018}}</ref>

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The latest version, JDBC 4.3, is specified by a maintenance release 3 of JSR 221<ref>{{cite web|url=https://jcp.org/aboutJava/communityprocess/mrel/jsr221/index3.html|title=The Java Community Process(SM) Program - communityprocess - mrel|website=jcp.org|access-date=22 March 2018}}</ref> and is included in Java SE 9.<ref>{{cite web|url=http://docs.oracle.com/javase/9/docs/api/java/sql/package-summary.html|title=java.sql (Java SE 9 & JDK 9)|website=docs.oracle.com|access-date=22 March 2018}}</ref>

{| class="wikitable"

==Functionality==

|+ JDBC versions

JDBC ('Java Database Connectivity') allows multiple implementations to exist and be used by the same application. The API provides a mechanism for dynamically loading the correct Java packages and registering them with the JDBC Driver Manager. The Driver Manager is used as a connection factory for creating JDBC connections.

|-

! JDBC version !! Java version !! Release Type !! Release date

JDBC connections support creating and executing statements. These may be update statements such as SQL's [[Create (SQL)|CREATE]], [[Insert (SQL)|INSERT]], [[Update (SQL)|UPDATE]] and [[Delete (SQL)|DELETE]], or they may be query statements such as [[Select (SQL)|SELECT]]. Additionally, stored procedures may be invoked through a JDBC connection. JDBC represents statements using one of the following classes:

|-

* {{Javadoc:SE|java/sql|Statement}} &ndash; the statement is sent to the database server each and every time.

| 1.1 || JDK 1.1 || Main || 1997-02-19.<ref name="JDK 1.1 release" />

* {{Javadoc:SE|java/sql|PreparedStatement}} &ndash; the statement is cached and then the [[Query plan|execution path]] is pre-determined on the database server allowing it to be executed multiple times in an efficient manner.

|-

* {{Javadoc:SE|java/sql|CallableStatement}} &ndash; used for executing [[stored procedures]] on the database.

| [https://www.jcp.org/en/jsr/detail?id=54 3.0] || J2SE 1.4 || Main || 2002-05-09

|-

Update statements such as INSERT, UPDATE and DELETE return an update count that indicates how many [[Row (database)|rows]] were affected in the database. These statements do not return any other information.

| [https://www.jcp.org/en/jsr/detail?id=221 4.0] || Java SE 6 || Main || 2006-12-11

|-

Query statements return a JDBC row result set. The row result set is used to walk over the [[result set]]. Individual [[Column (database)|columns]] in a row are retrieved either by name or by column number. There may be any number of rows in the result set. The row result set has metadata that describes the names of the columns and their types.

| [https://www.jcp.org/en/jsr/detail?id=221 4.1] || Java SE 7 || Maintenance || 2011-10-13

|-

There is an extension to the basic JDBC API in the {{Javadoc:SE|package=javax.sql|javax/sql}}.

| [https://www.jcp.org/en/jsr/detail?id=221 4.2] || Java SE 8 || Maintenance || 2014-03-04

|-

JDBC connections are often managed via a [[connection pool]] rather than obtained directly from the driver.

| [https://www.jcp.org/en/jsr/detail?id=221 4.3] || Java SE 9 || Maintenance || 2017-09-21

|}

==Functionality==

{| class="wikitable floatright"

|+ Host database types which Java can convert to with a function

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|}

Since JDBC ('Javais Databasemostly Connectivity')a collection of interface definitions and specifications, it allows multiple implementations of these interfaces to exist and be used by the same application at runtime. The API provides a mechanism for dynamically loading the correct Java packages and registering them with the JDBC Driver Manager ({{code|DriverManager}}). The Driver Manager{{code|DriverManager}} is used as a connection{{java|Connection}} [[Factory (object-oriented programming)|factory]] for creating JDBC connections.

JDBC connections support creating and executing statements. TheseJDBC mayconnections besupport update statements such as SQL's [[Create (SQL)|CREATE]], [[Insert (SQL)|INSERT]], [[Update (SQL)|UPDATE]] and [[Delete (SQL)|DELETE]], or they may be query statements such as [[Select (SQL)|SELECT]]. Additionally, stored procedures may be invoked through a JDBC connection. JDBC represents statements using one of the following classes:

* {{Javadoc:SE|java/sql|Statement|module=java.sql}} &ndash; the {{java|Statement}} is sent to the database server each and every time. In other words, the {{java|Statement}} methods are executed using SQL statements to obtain a {{code|ResultSet}} object containing the data.{{sfn | Bai | 2022 | p=74}}

* {{Javadoc:SE|java/sql|PreparedStatement|module=java.sql}} &ndash; {{code|PreparedStatement}} is a subinterface of the {{code|Statement}} interface.{{sfn | Bai | 2022 | p=74}} The statement is cached and then the [[Query plan|execution path]] is pre-determined on the database server, allowing it to be executed multiple times in an efficient manner.{{sfn | Bai | 2022 | p=74}} {{code|PreparedStatement}} is used to execute pre-compiled SQL statements.{{sfn | Bai | 2022 | p=74}} Running pre-compiled statements increases statement execution efficiency and performance. The {{code|PreparedStatement}} is often used for dynamic statement where some input parameters must be passed into the target database.{{sfn | Bai | 2022 | loc=§4.2.3.5 More About the Execution Methods | pp=122-124}} The

{{code|PreparedStatement}} allows the dynamic query to vary depending on the query parameter.{{sfn | Bai | 2022 | loc= §3.2 JDBC Components and Architecture | pp=72-74}}

* {{Javadoc:SE|java/sql|CallableStatement|module=java.sql}} &ndash; {{code|CallableStatement}} is a subinterface of the {{code|Statement}} interface.{{sfn | Bai | 2022 | loc= §3.2 JDBC Components and Architecture | pp=72-74}} It is used for executing [[stored procedures]] on the database.{{sfn | Bai | 2022 | loc= §3.2 JDBC Components and Architecture | pp=72-74}}{{sfn | Horstmann | 2022 | loc=§5.5.3 SQL Escapes}} Both input and output parameters must be passed into the database for stored procedures.{{sfn | Bai | 2022 | loc= §4.2.3.5 JDBC Components and Architecture | pp=122-124}}

Update statements such as INSERT, UPDATE and DELETE return an update count thatindicating indicatesthe hownumber manyof [[Row (database)|rows]] were affected in the database as an integer.{{sfn | Bai | 2022 | loc= §4.2.3.5 JDBC Components and Architecture | pp=122-124}} These statements do not return any other information.

Query statements return a JDBC row result set. The row result set is used to walk over the [[result set]]. Individual [[Column (database)|columns]] in a row are retrieved either by name or by column number. There may be any number of rows in the result set. The row result set has metadata that describes the names of the columns and their types.

There is an extension to the basic JDBC API in the {{Javadoc:SE|packagemodule=javaxjava.sql|package=javax/.sql|monotype=y}}.

JDBC connections are often managed via a [[connection pool]] rather than obtained directly from the driver.{{sfn | Bai | 2022 | loc=§3.5.1 JDBC DataSource | p=83}}

==Examples==

When a Java application needs a database connection, one of the <code>DriverManager.getConnection()</code> methods is used to create a JDBC connection{{java|Connection}}. The URL used is dependent upon the particular database and JDBC driver. It will always begin with the "jdbc:" protocol, but the rest is up to the particular vendor.

<syntaxhighlight lang="java5java">

Connection conn = DriverManager.getConnection(

"jdbc:somejdbcvendor:other data needed by some jdbc vendor",

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} catch (Throwable e) { /* Propagate the original exception

instead of this one that you want just logged */

logger.warn("Could not close JDBC Connection", e);

}

}

</syntaxhighlight>

Starting from Java SE 7 you can use Java's [http://docs.oracle.com/javase/tutorial/essential/exceptions/tryResourceClose.html try-with-resources] statement to makesimplify the above code simpler:

<syntaxhighlight lang="java5java">

try (Connection conn = DriverManager.getConnection(

"jdbc:somejdbcvendor:other data needed by some jdbc vendor",

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</syntaxhighlight>

Once a connection is established, a statement{{java|Statement}} can be created.

<syntaxhighlight lang="java5java">

try (Statement stmt = conn.createStatement()) {

stmt.executeUpdate("INSERT INTO MyTable(name) VALUES ('my name')");

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</syntaxhighlight>

Note that Connections{{java|Connection}}s, Statements{{java|Statement}}s, and ResultSets{{java|ResultSet}}s often tie up [[operating system]] resources such as sockets or [[file descriptor]]s. In the case of Connections{{java|Connection}}s to remote database servers, further resources are tied up on the server, e.g., [[Cursor (databases)|cursors]] for currently open ResultSets{{java|ResultSet}}s.

It is vital to <code>close()</code> any JDBC object as soon as it has played its part;

[[Garbage collection (computer science)|garbage collection]] should not be relied upon.

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Data is retrieved from the database using a database query mechanism. The example below shows creating a statement and executing a query.

<syntaxhighlight lang="java5java">

try (Statement stmt = conn.createStatement();

ResultSet rs = stmt.executeQuery("SELECT * FROM MyTable")

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for (int i = 1; i <= numColumns; i++) {

// Column numbers start at 1.

// Also, there are many methods on the result set to return

// the column as a particular type. Refer to the Sun documentation

// for the list of valid conversions.

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</syntaxhighlight>

AnThe following code is an example of a <code>PreparedStatement</code> query, usingwhich uses <code>conn</code> and class from the first example.:

<syntaxhighlight lang="java5java">

try (PreparedStatement ps =

conn.prepareStatement("SELECT i.*, j.* FROM Omega i, Zappa j WHERE i.name = ? AND j.num = ?")

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for (int i = 1; i <= numColumns; i++) {

// Column numbers start at 1.

// Also, there are many methods on the result set to return

// the column as a particular type. Refer to the Sun documentation

// for the list of valid conversions.

Line 212 ⟶ 228:

</syntaxhighlight>

If a database operation fails, JDBC raises an {{Javadoc:SE|java/sql|SQLException|module=java.sql}}. There is typically very little one can do to recover from such an error, apart from logging it with as much detail as possible. It is recommended that the {{code|SQLException}} be translated into an application ___domain exception (an unchecked one) that eventually results in a transaction rollback and a notification to the user.

AnThe following code is an example of a [[database transaction]]:

<syntaxhighlight lang="java5java">

boolean autoCommitDefault = conn.getAutoCommit();

try {

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For an example of a <code>CallableStatement</code> (to call stored procedures in the database), see the {{Javadoc:SE-guide|jdbc/getstart/callablestatement.html|JDBC API Guide}} documentation.

<syntaxhighlight lang="java5java">

import java.sql.Connection;

import java.sql.DriverManager;

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}

</syntaxhighlight>

==JDBC drivers==

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* [[JDBC driver#Type 4 Driver - Database-Protocol Driver(Pure Java Driver)|Type 4]], the pure-java driver that uses database native protocol.

Note also a type called an [[internal JDBC driver]] - a driver embedded with [[Java Runtime Environment|JRE]] in Java-enabled SQL databases. It is used for [[Java stored procedure]]s. This does not fit into the classification scheme above, although it would likely resemble either a type 2 or type 4 driver (depending on whether the database itself is implemented in Java or not). An example of this is the KPRB (Kernel Program Bundled) driver<ref>

{{cite book

| last1 = Greenwald

Line 295 ⟶ 310:

}}

</ref>

supplied with [[Oracle Database | Oracle RDBMS]]. "jdbc:default:connection" offers a relatively standard way of making such a connection (at least the Oracle database and [[Apache Derby]] support it). However, in the case of an internal JDBC driver, the JDBC client actually runs as part of the database being accessed, and so can access data directly rather than through network protocols.

===Sources===

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* [[Simba Technologies]] ships an SDK for building custom JDBC Drivers for any custom/proprietary relational data source

* CData Software ships type 4 JDBC Drivers for various applications, databases, and Web APIs.<ref>{{cite web|url=http://www.cdata.com/jdbc/|title=JDBC Drivers - CData Software|website=CData Software|access-date=22 March 2018}}</ref>

* RSSBus Type 4 JDBC Drivers for applications, databases, and web services<ref>{{cite web|url=http://www.rssbus.com/jdbc/|title=JDBC Drivers - CData Software|website=CData Software|access-date=22 March 2018|archive-date=22 December 2015|archive-url=https://web.archive.org/web/20151222115409/http://www.rssbus.com/jdbc/|url-status=dead}}</ref>

* DataDirect Technologies provides a comprehensive suite of fast Type 4 JDBC drivers for all major database they advertise as Type 5<ref name=datadirect>{{cite web

| url=http://www.datadirect.com/products/features/data-connectivity/type-5-jdbc/index.html

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| url=https://github.com/schemacrawler/SchemaCrawler

| title=SchemaCrawler

| work=SourceForgeGitHub

}}</ref> is an open source API that leverages JDBC, and makes database metadata available as plain old Java objects (POJOs)

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* [[Object–relational mapping]] (ORM)

==References Citations ==

{{reflist}}

== References ==

* {{cite book | last=Bai | first=Ying | title=SQL Server Database Programming with Java | publisher=[[Springer International Publishing]] | publication-place=Cham | year=2022 | isbn=978-3-030-92686-1 | doi=10.1007/978-3-031-06553-8}}

* {{cite book | last=Horstmann | first=Cay | title=Core Java | publisher=Oracle Press Java | date=April 15, 2022 | isbn=978-0-13-787107-0}}

==External links==

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{{Wikibooks|Java Programming/Database Programming}}

* {{Javadoc:SE-guide|jdbc|JDBC API Guide}}

* {{Javadoc:SE|package=java.sql|java/sql|module=java.sql}} API [[Javadoc]] documentation

* {{Javadoc:SE|package=javax.sql|javax/sql|module=java.sql}} API Javadoc documentation

* [https://web.archive.org/web/20160111210342/http://orbroker.org/ O/R Broker] Scala JDBC framework

* [http://www.hsqldb.org/doc/2.0/util-guide/sqltool-chapt.html SqlTool] Open source, command-line, generic JDBC client utility. Works with any JDBC-supporting database.

* [http://codeoftheday.blogspot.com/2012/12/java-database-connectivity-jdbc-url.html JDBC URL Strings and related information of All Databases.]

{{DEFAULTSORT:Database Connectivity}}

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