helma.Database

Object
   |
   +--helma.Database

This class provides access to a relational database through JDBC. There are two convenient ways to create instances of this class.

The first is to use helma.Database.getInstance() to obtain a connection to a DB that is defined in the application's db.properties and managed by Helma. The second way is to define and create a database connection locally using helma.Database.createInstance() and passing it all necessary parameters.

This class provides two ways of interaction: The query() method allows to issue SQL queries, returning a result set. The execute() provides a way to issue SQL statements that do not return a result set.

Database connections allocated by this class are be managed and eventually disposed by Helma.

Constructor Detail

helma.Database

helma.Database(<DbSource> source)

Constructor for Database objects, providing access through relational databases through JDBC. It is usually simpler to use one of the factory methods createInstance() or getInstance().

Parameters:
source - instance of a helma.objectmodel.db.DbSource

execute

int execute(<String> sql)

Executes the given SQL statement, which may be an INSERT, UPDATE, or DELETE statement or an SQL statement that returns nothing, such as an SQL data definition statement. The return value is an integer that indicates the number of rows that were affected by the statement.

Parameters:
sql - an SQL statement

Returns:
either the row count for INSERT, UPDATE or DELETE statements, or 0 for SQL statements that return nothing

getConnection

java.sql.Connection getConnection()

Get the java.sql.Connection for this Database instance. This can be used to operate on the connection directly, without going through the helma.Database class.

Returns:
the JDBC connection

getDriverName

String getDriverName()

Return the name of the JDBC driver used by this Database instance.

Returns:
the JDBC driver name

getName

String getName()

Return the name of the Helma DbSource object.

Returns:
the DbSource name

getProductName

String getProductName()

Returns the lower case name of the underlying database product.

Returns:
the name of the DB product

isMySql

boolean isMySql()

Returns true if this is a MySQL database.

Returns:
true if this is an MySQL database.

isOracle

boolean isOracle()

Returns true if this is an Oracle database.

Returns:
true if this is an Oracle database.

isPostgreSql

boolean isPostgreSql()

Returns true if this is a PostgreSQL database.

Returns:
true if this is a PostgreSQL database.

query

Array query(<String> sql)

Executes the given SQL statement. The result set is returned as JavaScript Array containing a JavaScript Object for each result.

Parameters:
sql - an SQL query statement

Returns:
an Array containing the result set

createInstance

<static> helma.Database createInstance(<String> driver, <String> url, <String> name, <String> user, <String> password)

Create a new Database instance using the given parameters.

Some of the parameters support shortcuts for known database products. The url parameter recognizes the values "mysql", "oracle" and "postgresql". For those databases, it is also possible to pass just hostname or hostname:port as url parameters instead of the full JDBC URL.

Parameters:
driver - the class name of the JDBC driver. As shortcuts, the values "mysql", "oracle" and "postgresql" are recognized.
url - the JDBC URL.
name - the name of the database to use
user - the the username
password - the password

Returns:
a helma.Database instance

getInstance

<static> helma.Database getInstance(<String> name)

Get a Database instance using the Database source defined in the application's db.properties file with the given name.

Parameters:
name - the name of the DB source as defined in db.properties

Returns:
a helma.Database instance