com.webobjects.eoaccess
Class EOSQLExpressionFactory

java.lang.Object
  com.webobjects.eoaccess.EOSQLExpressionFactory

Direct Known Subclasses:

JDBCExpressionFactory

public class EOSQLExpressionFactory

extends Object

EOSQLExpressionFactory builds SQL statements for adaptor channels. You don't typically use instances of EOSQLExpression; rather, you use EOSQLExpression subclasses written to work with a particular RDBMS and corresponding adaptor. A concrete subclass of EOSQLExpression overrides many of its methods in terms of the query language syntax for its specific RDBMS. EOSQLExpression objects are used internally by the Framework, and unless you're creating a concrete adaptor, you won't ordinarily need to interact with EOSQLExpression objects yourself. You most commonly create and use an EOSQLExpression object when you want to send an SQL statement directly to the server. In this case, you simply create an expression with the EOSQLExpression class method expressionForString, and send the expression object to an adaptor channel using EOAdaptorChannel's evaluateExpression method.

See Also:

expressionForString(String)

Constructor Summary

EOSQLExpressionFactory(EOAdaptor adaptor)
Creates an EOSQLExpressionFactory capable of creating EOSQLExpressions for the specified EOAdaptor.

Method Summary

EOAdaptor	adaptor() Returns the EOAdaptor for which this factory creates expressions.
EOSQLExpression	createExpression(EOEntity entity) Creates a new instance of the factory's EOSQLExpression class and assigns the parameter entity to that expression.
EOSQLExpression	deleteStatementWithQualifier(EOQualifier qualifier, EOEntity entity) Creates and returns an SQL DELETE expression to delete the rows described by qualifier.
Class	expressionClass() Returns the subclass of EOSQLExpression used by this factory to create expressions
EOSQLExpression	expressionForEntity(EOEntity entity) Creates a new instance of the factory's EOSQLExpression class and assigns the parameter entity to that expression.
EOSQLExpression	expressionForString(String string) Creates and returns an SQL expression containing the string parameter.
EOSQLExpression	insertStatementForRow(NSDictionary row, EOEntity entity) Creates and returns an SQL INSERT expression to insert row.
EOSQLExpression	selectStatementForAttributes(NSArray attributes, boolean yn, EOFetchSpecification fetchSpec, EOEntity entity) Creates and returns an SQL SELECT expression.
EOSQLExpression	updateStatementForRow(NSDictionary row, EOQualifier qualifier, EOEntity entity) Creates and returns an SQL UPDATE expression to update the row identified by qualifier with the values in row.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

EOSQLExpressionFactory

public EOSQLExpressionFactory(EOAdaptor adaptor)

Creates an EOSQLExpressionFactory capable of creating EOSQLExpressions for the specified EOAdaptor.

Parameters:

adaptor - the adaptor for which EOSQLExpressions are to be created

Method Detail

adaptor

public EOAdaptor adaptor()

Returns the EOAdaptor for which this factory creates expressions.

Returns:

An instance of EOAdaptor for which this factory creates expressions

createExpression

public EOSQLExpression createExpression(EOEntity entity)

Creates a new instance of the factory's EOSQLExpression class and assigns the parameter entity to that expression.

Parameters:

entity - the EOEntity to which the EOSQLExpression is assigned

Returns:

The EOSQLExpression created

deleteStatementWithQualifier

public EOSQLExpression deleteStatementWithQualifier(EOQualifier qualifier,
                                                    EOEntity entity)

Creates and returns an SQL DELETE expression to delete the rows described by qualifier.

Creates an instance of EOSQLExpression, initializes it with entity (an EOEntity object), and sends it a prepareDeleteExpressionForQualifier message.

The expression created with this method does not use table aliases because Enterprise Objects Framework assumes that all INSERT, UPDATE, and DELETE statements are single-table operations. To generate INSERT statements that do use table aliases, you must override prepareInsertExpressionWithRow to send a setUseAliases(true) message prior to invoking super's version.

Parameters:

entity - the EOEntity from which the row will be deleted

qualifier - an EOQualifier identifying the row to be deleted

Returns:

The new EOSQLExpression

expressionClass

public Class expressionClass()

Returns the subclass of EOSQLExpression used by this factory to create expressions

Returns:

The class to by this factory to create expressions

expressionForEntity

public EOSQLExpression expressionForEntity(EOEntity entity)

Creates a new instance of the factory's EOSQLExpression class and assigns the parameter entity to that expression. It is the same as createExpression.

Parameters:

entity - the EOEntity to which the EOSQLExpression is assigned

Returns:

The EOSQLExpression

See Also:

createExpression(EOEntity)

expressionForString

public EOSQLExpression expressionForString(String string)

Creates and returns an SQL expression containing the string parameter.

Parameters:

string - the string from which the expression should be created

Returns:

The EOSQLExpression

insertStatementForRow

public EOSQLExpression insertStatementForRow(NSDictionary row,
                                             EOEntity entity)

Creates and returns an SQL INSERT expression to insert row. Creates an instance of EOSQLExpression, initializes it with entity, and sends it prepareInsertExpressionWithRow(). Raises an IllegalArgumentException if entity is null.

The expression created with this method does not use table aliases because Enterprise Objects Framework assumes that all INSERT, UPDATE, and DELETE statements are single-table operations. To generate INSERT statements that do use table aliases, you must override prepareInsertExpressionWithRow to send a setUseAliases(true) message prior to invoking super's version.

Parameters:

row - an NSDictionary containing column name (key) to value (value) mappings

entity - the EOEntity into which the row will be inserted

Returns:

The new EOSQLExpression

selectStatementForAttributes

public EOSQLExpression selectStatementForAttributes(NSArray attributes,
                                                    boolean yn,
                                                    EOFetchSpecification fetchSpec,
                                                    EOEntity entity)

Creates and returns an SQL SELECT expression.

Creates an instance of EOSQLExpression, initializes it with entity, and sends it prepareSelectExpressionWithAttributes. The expression created with this method uses table aliases.

Raises an IllegalArgumentException if attributes is null or empty, fetchSpecification is null, or entity is null.

The expression created with this method uses table aliases. To generate SELECT statements that doesn't use them, you must override prepareSelectExpressionWithAttributes() to send a setUseAliases(false) message prior to invoking super's version.

Parameters:

attributes -

entity - the EOEntity against which the select will run

fetchSpec - the EOFetchSpecification describing the row(s) to be fetched

yn - boolean specifying whether (true) or not (false) shared locks should be held

Returns:

The new EOSQLExpression

updateStatementForRow

public EOSQLExpression updateStatementForRow(NSDictionary row,
                                             EOQualifier qualifier,
                                             EOEntity entity)

Creates and returns an SQL UPDATE expression to update the row identified by qualifier with the values in row. row should only contain entries for values that have actually changed. Creates an instance of EOSQLExpression, initializes it with entity, and sends it prepareUpdateExpressionWithRow.

Raises an IllegalArgumentException if any parameter is null.

The expression created with this method does not use table aliases because Enterprise Objects Framework assumes that all INSERT, UPDATE, and DELETE statements are single-table operations. To generate INSERT statements that do use table aliases, you must override prepareInsertExpressionWithRow to send a setUseAliases(true) message prior to invoking super's version.

Parameters:

row - an NSDictionary containing column name (key) to value (value) mappings

entity - the EOEntity in which the row will be updated

qualifier - an EOQualifier identifying the row to be updated

Returns:

The new EOSQLExpression