Module java.sql

# Package java.sql

package java.sql
Provides the API for accessing and processing data stored in a data source (usually a relational database) using the Java programming language. This API includes a framework whereby different drivers can be installed dynamically to access different data sources. Although the JDBC API is mainly geared to passing SQL statements to a database, it provides for reading and writing data from any data source with a tabular format. The reader/writer facility, available through the `javax.sql.RowSet` group of interfaces, can be customized to use and update data from a spread sheet, flat file, or any other tabular data source.

## What the JDBC 4.3 API Includes

The JDBC 4.3 API includes both the `java.sql` package, referred to as the JDBC core API, and the `javax.sql` package, referred to as the JDBC Optional Package API. This complete JDBC API is included in the Java Standard Edition (Java SE), version 7. The `javax.sql` package extends the functionality of the JDBC API from a client-side API to a server-side API, and it is an essential part of the Java Enterprise Edition (Java EE) technology.

## Versions

The JDBC 4.3 API incorporates all of the previous JDBC API versions:

- The JDBC 4.2 API
- The JDBC 4.1 API
- The JDBC 4.0 API
- The JDBC 3.0 API
- The JDBC 2.1 core API
- The JDBC 2.0 Optional Package API
  (Note that the JDBC 2.1 core API and the JDBC 2.0 Optional Package API together are referred to as the JDBC 2.0 API.)
- The JDBC 1.2 API
- The JDBC 1.0 API

Classes, interfaces, methods, fields, constructors, and exceptions have the following "since" tags that indicate when they were introduced into the Java platform. When these "since" tags are used in Javadoc comments for the JDBC API, they indicate the following:

- Since 9 -- new in the JDBC 4.3 API and part of the Java SE platform, version 9
- Since 1.8 -- new in the JDBC 4.2 API and part of the Java SE platform, version 8
- Since 1.7 -- new in the JDBC 4.1 API and part of the Java SE platform, version 7
- Since 1.6 -- new in the JDBC 4.0 API and part of the Java SE platform, version 6
- Since 1.4 -- new in the JDBC 3.0 API and part of the J2SE platform, version 1.4
- Since 1.2 -- new in the JDBC 2.0 API and part of the J2SE platform, version 1.2
- Since 1.1 or no "since" tag -- in the original JDBC 1.0 API and part of the JDK, version 1.1

NOTE: Many of the new features are optional; consequently, there is some variation in drivers and the features they support. Always check your driver's documentation to see whether it supports a feature before you try to use it.

NOTE: The class `SQLPermission` was added in the Java 2 SDK, Standard Edition, version 1.3 release. This class is used to prevent unauthorized access to the logging stream associated with the `DriverManager`, which may contain information such as table names, column data, and so on.

## What the `java.sql` Package Contains

The `java.sql` package contains API for the following:

- Making a connection with a database via the `DriverManager` facility
  - `DriverManager` class -- makes a connection with a driver
  - `SQLPermission` class -- provides permission when code running within a Security Manager, such as an applet, attempts to set up a logging stream through the `DriverManager`
  - `Driver` interface -- provides the API for registering and connecting drivers based on JDBC technology ("JDBC drivers"); generally used only by the `DriverManager` class
  - `DriverPropertyInfo` class -- provides properties for a JDBC driver; not used by the general user
- Sending SQL statements to a database
  - `Statement` -- used to send basic SQL statements
  - `PreparedStatement` -- used to send prepared statements or basic SQL statements (derived from `Statement`)
  - `CallableStatement` -- used to call database stored procedures (derived from `PreparedStatement`)
  - `Connection` interface -- provides methods for creating statements and managing connections and their properties
  - `Savepoint` -- provides savepoints in a transaction
- Retrieving and updating the results of a query
  - `ResultSet` interface
- Standard mappings for SQL types to classes and interfaces in the Java programming language
  - `Array` interface -- mapping for SQL `ARRAY`
  - `Blob` interface -- mapping for SQL `BLOB`
  - `Clob` interface -- mapping for SQL `CLOB`
  - `Date` class -- mapping for SQL `DATE`
  - `NClob` interface -- mapping for SQL `NCLOB`
  - `Ref` interface -- mapping for SQL `REF`
  - `RowId` interface -- mapping for SQL `ROWID`
  - `Struct` interface -- mapping for SQL `STRUCT`
  - `SQLXML` interface -- mapping for SQL `XML`
  - `Time` class -- mapping for SQL `TIME`
  - `Timestamp` class -- mapping for SQL `TIMESTAMP`
  - `Types` class -- provides constants for SQL types
- Custom mapping an SQL user-defined type (UDT) to a class in the Java programming language
  - `SQLData` interface -- specifies the mapping of a UDT to an instance of this class
  - `SQLInput` interface -- provides methods for reading UDT attributes from a stream
  - `SQLOutput` interface -- provides methods for writing UDT attributes back to a stream
- Metadata
  - `DatabaseMetaData` interface -- provides information about the database
  - `ResultSetMetaData` interface -- provides information about the columns of a `ResultSet` object
  - `ParameterMetaData` interface -- provides information about the parameters to `PreparedStatement` commands
- Exceptions
  - `SQLException` -- thrown by most methods when there is a problem accessing data and by some methods for other reasons
  - `SQLWarning` -- thrown to indicate a warning
  - `DataTruncation` -- thrown to indicate that data may have been truncated
  - `BatchUpdateException` -- thrown to indicate that not all commands in a batch update executed successfully

### `java.sql` and `javax.sql` Features Introduced in the JDBC 4.3 API

- Added `Sharding` support
- Enhanced `Connection` to be able to provide hints to the driver that a request, an independent unit of work, is beginning or ending
- Enhanced `DatabaseMetaData` to determine if Sharding is supported
- Added the method `drivers` to `DriverManager` to return a Stream of the currently loaded and available JDBC drivers
- Added support to `Statement` for enquoting literals and simple identifiers
- Clarified the Java SE version that methods were deprecated

### `java.sql` and `javax.sql` Features Introduced in the JDBC 4.2 API

- Added `JDBCType` enum and `SQLType` interface
- Support for `REF CURSORS` in `CallableStatement`
- `DatabaseMetaData` methods to return maximum Logical LOB size and if Ref Cursors are supported
- Added support for large update counts

### `java.sql` and `javax.sql` Features Introduced in the JDBC 4.1 API

- Allow `Connection`, `ResultSet` and `Statement` objects to be used with the try-with-resources statement
- Support added to `CallableStatement` and `ResultSet` to specify the Java type to convert to via the `getObject` method
- `DatabaseMetaData` methods to return PseudoColumns and if a generated key is always returned
- Added support to `Connection` to specify a database schema, abort and timeout a physical connection.
- Added support to close a `Statement` object when its dependent objects have been closed
- Support for obtaining the parent logger for a `Driver`, `DataSource`, `ConnectionPoolDataSource` and `XADataSource`

### `java.sql` and `javax.sql` Features Introduced in the JDBC 4.0 API

- auto java.sql.Driver discovery -- no longer need to load a `java.sql.Driver` class via `Class.forName`
- National Character Set support added
- Support added for the SQL:2003 XML data type
- SQLException enhancements -- Added support for cause chaining; New SQLExceptions added for common SQLState class value codes
- Enhanced Blob/Clob functionality -- Support provided to create and free a Blob/Clob instance as well as additional methods added to improve accessibility
- Support added for accessing a SQL ROWID
- Support added to allow a JDBC application to access an instance of a JDBC resource that has been wrapped by a vendor, usually in an application server or connection pooling environment.
- Availability to be notified when a `PreparedStatement` that is associated with a `PooledConnection` has been closed or the driver determines is invalid

### `java.sql` and `javax.sql` Features Introduced in the JDBC 3.0 API

- Pooled statements -- reuse of statements associated with a pooled connection
- Savepoints -- allow a transaction to be rolled back to a designated savepoint
- Properties defined for `ConnectionPoolDataSource` -- specify how connections are to be pooled
- Metadata for parameters of a `PreparedStatement` object
- Ability to retrieve values from automatically generated columns
- Ability to have multiple `ResultSet` objects returned from `CallableStatement` objects open at the same time
- Ability to identify parameters to `CallableStatement` objects by name as well as by index
- `ResultSet` holdability -- ability to specify whether cursors should be held open or closed at the end of a transaction
- Ability to retrieve and update the SQL structured type instance that a `Ref` object references
- Ability to programmatically update `BLOB`, `CLOB`, `ARRAY`, and `REF` values.
- Addition of the `java.sql.Types.DATALINK` data type -- allows JDBC drivers access to objects stored outside a data source
- Addition of metadata for retrieving SQL type hierarchies

### `java.sql` Features Introduced in the JDBC 2.1 Core API

- Scrollable result sets--using new methods in the `ResultSet` interface that allow the cursor to be moved to a particular row or to a position relative to its current position
- Batch updates
- Programmatic updates--using `ResultSet` updater methods
- New data types--interfaces mapping the SQL3 data types
- Custom mapping of user-defined types (UDTs)
- Miscellaneous features, including performance hints, the use of character streams, full precision for `java.math.BigDecimal` values, additional security, and support for time zones in date, time, and timestamp values.

### `javax.sql` Features Introduced in the JDBC 2.0 Optional Package API

- The `DataSource` interface as a means of making a connection. The Java Naming and Directory Interface (JNDI) is used for registering a `DataSource` object with a naming service and also for retrieving it.
- Pooled connections -- allowing connections to be used and reused
- Distributed transactions -- allowing a transaction to span diverse DBMS servers
- `RowSet` technology -- providing a convenient means of handling and passing data

### Custom Mapping of UDTs

A user-defined type (UDT) defined in SQL can be mapped to a class in the Java programming language. An SQL structured type or an SQL `DISTINCT` type are the UDTs that may be custom mapped. The following three steps set up a custom mapping:

1. Defining the SQL structured type or `DISTINCT` type in SQL
2. Defining the class in the Java programming language to which the SQL UDT will be mapped. This class must implement the `SQLData` interface.
3. Making an entry in a `Connection` object's type map that contains two things:
   - the fully-qualified SQL name of the UDT
   - the `Class` object for the class that implements the `SQLData` interface

When these are in place for a UDT, calling the methods `ResultSet.getObject` or `CallableStatement.getObject` on that UDT will automatically retrieve the custom mapping for it. Also, the `PreparedStatement.setObject` method will automatically map the object back to its SQL type to store it in the data source.

## Package Specification

- JDBC 4.3 Specification

## Related Documentation

- Lesson:JDBC Basics(The Java Tutorials > JDBC Database Access)
- “JDBC API Tutorial and Reference, Third Edition”

- Class
  Description
  Array
  The mapping in the Java programming language for the SQL type `ARRAY`.
  BatchUpdateException
  The subclass of `SQLException` thrown when an error occurs during a batch update operation.
  Blob
  The representation (mapping) in the Java programming language of an SQL `BLOB` value.
  CallableStatement
  The interface used to execute SQL stored procedures.
  ClientInfoStatus
  Enumeration for status of the reason that a property could not be set via a call to `Connection.setClientInfo`
  Clob
  The mapping in the Java programming language for the SQL `CLOB` type.
  Connection
  A connection (session) with a specific database.
  ConnectionBuilder
  A builder created from a `DataSource` object, used to establish a connection to the database that the `data source` object represents.
  DatabaseMetaData
  Comprehensive information about the database as a whole.
  DataTruncation
  An exception thrown as a `DataTruncation` exception (on writes) or reported as a `DataTruncation` warning (on reads) when a data values is unexpectedly truncated for reasons other than its having exceeded `MaxFieldSize`.
  Date
  A thin wrapper around a millisecond value that allows JDBC to identify this as an SQL `DATE` value.
  Driver
  The interface that every driver class must implement.
  DriverAction
  An interface that must be implemented when a Driver wants to be notified by `DriverManager`.
  DriverManager
  The basic service for managing a set of JDBC drivers.
  DriverPropertyInfo
  Driver properties for making a connection.
  JDBCType
  Defines the constants that are used to identify generic SQL types, called JDBC types.
  NClob
  The mapping in the Java programming language for the SQL `NCLOB` type.
  ParameterMetaData
  An object that can be used to get information about the types and properties for each parameter marker in a `PreparedStatement` object.
  PreparedStatement
  An object that represents a precompiled SQL statement.
  PseudoColumnUsage
  Enumeration for pseudo/hidden column usage.
  Ref
  The mapping in the Java programming language of an SQL `REF` value, which is a reference to an SQL structured type value in the database.
  ResultSet
  A table of data representing a database result set, which is usually generated by executing a statement that queries the database.
  ResultSetMetaData
  An object that can be used to get information about the types and properties of the columns in a `ResultSet` object.
  RowId
  The representation (mapping) in the Java programming language of an SQL ROWID value.
  RowIdLifetime
  Enumeration for RowId life-time values.
  Savepoint
  The representation of a savepoint, which is a point within the current transaction that can be referenced from the `Connection.rollback` method.
  ShardingKey
  Interface used to indicate that this object represents a Sharding Key.
  ShardingKeyBuilder
  A builder created from a `DataSource` or `XADataSource` object, used to create a `ShardingKey` with sub-keys of supported data types.
  SQLClientInfoException
  The subclass of `SQLException` is thrown when one or more client info properties could not be set on a `Connection`.
  SQLData
  The interface used for the custom mapping of an SQL user-defined type (UDT) to a class in the Java programming language.
  SQLDataException
  The subclass of `SQLException` thrown when the SQLState class value is '22', or under vendor-specified conditions.
  SQLException
  An exception that provides information on a database access error or other errors.
  SQLFeatureNotSupportedException
  The subclass of `SQLException` thrown when the SQLState class value is '0A' ( the value is 'zero' A).
  SQLInput
  An input stream that contains a stream of values representing an instance of an SQL structured type or an SQL distinct type.
  SQLIntegrityConstraintViolationException
  The subclass of `SQLException` thrown when the SQLState class value is '23', or under vendor-specified conditions.
  SQLInvalidAuthorizationSpecException
  The subclass of `SQLException` thrown when the SQLState class value is '28', or under vendor-specified conditions.
  SQLNonTransientConnectionException
  The subclass of `SQLException` thrown for the SQLState class value '08', or under vendor-specified conditions.
  SQLNonTransientException
  The subclass of `SQLException` thrown when an instance where a retry of the same operation would fail unless the cause of the `SQLException` is corrected.
  SQLOutput
  The output stream for writing the attributes of a user-defined type back to the database.
  SQLPermission
  The permission for which the `SecurityManager` will check when code that is running an application with a `SecurityManager` enabled, calls the `DriverManager.deregisterDriver` method, `DriverManager.setLogWriter` method, `DriverManager.setLogStream` (deprecated) method, `SyncFactory.setJNDIContext` method, `SyncFactory.setLogger` method, `Connection.setNetworkTimeout` method, or the `Connection.abort` method.
  SQLRecoverableException
  The subclass of `SQLException` thrown in situations where a previously failed operation might be able to succeed if the application performs some recovery steps and retries the entire transaction or in the case of a distributed transaction, the transaction branch.
  SQLSyntaxErrorException
  The subclass of `SQLException` thrown when the SQLState class value is '42', or under vendor-specified conditions.
  SQLTimeoutException
  The subclass of `SQLException` thrown when the timeout specified by `Statement.setQueryTimeout`, `DriverManager.setLoginTimeout`, `DataSource.setLoginTimeout`,`XADataSource.setLoginTimeout` has expired.
  SQLTransactionRollbackException
  The subclass of `SQLException` thrown when the SQLState class value is '40', or under vendor-specified conditions.
  SQLTransientConnectionException
  The subclass of `SQLException` for the SQLState class value '08', or under vendor-specified conditions.
  SQLTransientException
  The subclass of `SQLException` is thrown in situations where a previously failed operation might be able to succeed when the operation is retried without any intervention by application-level functionality.
  SQLType
  An object that is used to identify a generic SQL type, called a JDBC type or a vendor specific data type.
  SQLWarning
  An exception that provides information on database access warnings.
  SQLXML
  The mapping in the JavaTM programming language for the SQL XML type.
  Statement
  The object used for executing a static SQL statement and returning the results it produces.
  Struct
  The standard mapping in the Java programming language for an SQL structured type.
  Time
  A thin wrapper around the `java.util.Date` class that allows the JDBC API to identify this as an SQL `TIME` value.
  Timestamp
  A thin wrapper around `java.util.Date` that allows the JDBC API to identify this as an SQL `TIMESTAMP` value.
  Types
  The class that defines the constants that are used to identify generic SQL types, called JDBC types.
  Wrapper
  Interface for JDBC classes which provide the ability to retrieve the delegate instance when the instance in question is in fact a proxy class.