The SQL engine performs persistence of one object type against one
SQL database. It can only persist simple objects and extended
relationships. An SQL engine is created for each object type
represented by a database. When persisting, it requires a physical
connection that maps to the SQL database and the transaction
running on that database
getColumnInfoForIdentities
public SQLColumnInfo[] getColumnInfoForIdentities()
getDescriptor
public JDOClassDescriptor getDescriptor()
Used by
OQLQuery
to retrieve the class descriptor.
- the JDO class descriptor.
idToJava
protected Object idToJava(int index,
Object object)
load
public Object load(Object conn,
ProposedEntity entity,
Identity identity,
AccessMode accessMode)
throws PersistenceException
Loads the object from persistence storage. This method will load
the object fields from persistence storage based on the object's
identity. This method may return a stamp which can be used at a
later point to determine whether the copy of the object in
persistence storage is newer than the cached copy (see
store(Object,Identity,ProposedEntity,ProposedEntity)
). If
lock is true the object must be
locked in persistence storage to prevent concurrent updates.
- load in interface Persistence
conn
- An open connectionentity
- An Object[] to load field values intoidentity
- Identity of the object to load.accessMode
- The access mode (null equals shared)
- The object's stamp, or null
setExtends
public void setExtends(SQLEngine engine)
Mutator method for setting extends SQLEngine.
toJava
protected Object toJava(int field,
int column,
Object object)
toString
public String toString()