Class SQLRef

java.lang.Object

org.apache.derby.iapi.types.DataType

org.apache.derby.iapi.types.SQLRef

All Implemented Interfaces:

Externalizable, Serializable, Comparable, Formatable, Storable, TypedFormat, DataValueDescriptor, Orderable, RefDataValue

public class SQLRef
extends DataType
implements RefDataValue

See Also:

• Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
private static final int	BASE_MEMORY_USAGE
protected RowLocation	value

Fields inherited from interface DataValueDescriptor

UNKNOWN_LOGICAL_LENGTH

Fields inherited from interface Orderable

ORDER_OP_EQUALS, ORDER_OP_GREATEROREQUALS, ORDER_OP_GREATERTHAN, ORDER_OP_LESSOREQUALS, ORDER_OP_LESSTHAN

Constructor Summary

Constructors

Constructor	Description
SQLRef()
SQLRef(RowLocation rowLocation)

Method Summary

Modifier and Type	Method	Description
DataValueDescriptor	cloneValue(boolean forceMaterialization)	Clone this DataValueDescriptor.
boolean	compare(int op, DataValueDescriptor other, boolean orderedNulls, boolean unknownRV)	Compare this Orderable with a given Orderable for the purpose of qualification and sorting.
int	compare(DataValueDescriptor other)	Compare this Orderable with a given Orderable for the purpose of index positioning.
int	estimateMemoryUsage()	Estimate the memory usage in bytes of the data value and the overhead of the class.
int	getLength()	Gets the length of the data value.
DataValueDescriptor	getNewNull()	Get a new null value of the same type as this data value.
Object	getObject()	Gets the value in the data value descriptor as a int.
String	getString()	Gets the value in the data value descriptor as a String.
int	getTypeFormatId()	Return my format identifier.
String	getTypeName()	Get the SQL name of the datatype
int	hashCode()	Adding this overload makes it possible to use SQLRefs as keys in HashMaps.
boolean	isNull()	Return whether the value is null or not.
void	readExternal(ObjectInput in)
void	restoreToNull()	Restore this object to its (SQL)null value.
protected void	setFrom(DataValueDescriptor theValue)	Set the value of this DataValueDescriptor based on the value of the specified DataValueDescriptor.
void	setInto(PreparedStatement ps, int position)	Set this value into a PreparedStatement.
void	setValue(RowLocation rowLocation)	Set the value of this RefDataValue.
void	setValueFromResultSet(ResultSet resultSet, int colNumber, boolean isNullable)	Set the value based on the value for the specified DataValueDescriptor from the specified ResultSet.
String	toString()
void	writeExternal(ObjectOutput out)

Methods inherited from class DataType

checkHostVariable, cloneHolder, coalesce, compare, compare, compareTo, dataTypeConversion, equals, equals, flip, genericSetObject, getBoolean, getByte, getBytes, getDate, getDouble, getFloat, getInt, getLong, getShort, getStream, getTime, getTimestamp, getTraceString, getTypeName, greaterOrEquals, greaterThan, hasStream, in, invalidFormat, isNotNull, isNullOp, lessOrEquals, lessThan, normalize, notEquals, outOfRange, readExternalFromArray, recycle, setBigDecimal, setInto, setObject, setObjectForCast, setToNull, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, throwLangSetMismatch, throwLangSetMismatch, typePrecedence, typeToBigDecimal

Methods inherited from class Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface DataValueDescriptor

checkHostVariable, cloneHolder, coalesce, compare, compare, equals, getBoolean, getByte, getBytes, getDate, getDouble, getFloat, getInt, getLong, getShort, getStream, getTime, getTimestamp, getTraceString, greaterOrEquals, greaterThan, hasStream, in, isNotNull, isNullOp, lessOrEquals, lessThan, normalize, notEquals, readExternalFromArray, recycle, setBigDecimal, setInto, setObjectForCast, setToNull, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, typePrecedence, typeToBigDecimal

Field Details

value

protected RowLocation value

BASE_MEMORY_USAGE

private static final int BASE_MEMORY_USAGE

Constructor Details

SQLRef

public SQLRef()

SQLRef

public SQLRef(RowLocation rowLocation)

Method Details

estimateMemoryUsage

public int estimateMemoryUsage()

Description copied from interface: DataValueDescriptor

Estimate the memory usage in bytes of the data value and the overhead of the class.

Specified by:

estimateMemoryUsage in interface DataValueDescriptor

Returns:

the estimated memory usage

getString

public String getString()

Description copied from interface: DataValueDescriptor

Gets the value in the data value descriptor as a String. Throws an exception if the data value is not a string.

Specified by:

getString in interface DataValueDescriptor

Returns:

The data value as a String.

getObject

public Object getObject()

Description copied from class: DataType

Gets the value in the data value descriptor as a int. Throws an exception if the data value is not receivable as a int.

Specified by:

getObject in interface DataValueDescriptor

Overrides:

getObject in class DataType

Returns:

The data value as a int.

setFrom

protected void setFrom(DataValueDescriptor theValue)
                throws StandardException

Description copied from class: DataType

Set the value of this DataValueDescriptor based on the value of the specified DataValueDescriptor.

Overrides:

setFrom in class DataType

Parameters:

theValue - The DataValueDescriptor that holds the value to which we want to set this DataValueDescriptor's value.

Throws:

StandardException

getLength

public int getLength()

Description copied from interface: DataValueDescriptor

Gets the length of the data value. The meaning of this is implementation-dependent. For string types, it is the number of characters in the string. For numeric types, it is the number of bytes used to store the number. This is the actual length of this value, not the length of the type it was defined as. For example, a VARCHAR value may be shorter than the declared VARCHAR (maximum) length.

Specified by:

getLength in interface DataValueDescriptor

Returns:

The length of the data value

getTypeName

public String getTypeName()

Description copied from interface: DataValueDescriptor

Get the SQL name of the datatype

Specified by:

getTypeName in interface DataValueDescriptor

Returns:

The SQL name of the datatype

getTypeFormatId

public int getTypeFormatId()

Return my format identifier.

Specified by:

getTypeFormatId in interface TypedFormat

Returns:

The identifier. (A UUID stuffed in an array of 16 bytes).

See Also:

• TypedFormat.getTypeFormatId()

isNull

public boolean isNull()

Description copied from interface: Storable

Return whether the value is null or not.

Specified by:

isNull in interface Storable

Returns:

true if the value is null and false otherwise.

writeExternal

public void writeExternal(ObjectOutput out)
                   throws IOException

Specified by:

writeExternal in interface Externalizable

Throws:

IOException

readExternal

public void readExternal(ObjectInput in)
                  throws IOException,
ClassNotFoundException

Specified by:

readExternal in interface Externalizable

Throws:

IOException - Thrown on error reading the object

ClassNotFoundException - Thrown if the class of the object read from the stream can't be found (not likely, since it's supposed to be SQLRef).

See Also:

• Externalizable.readExternal(ObjectInput)

restoreToNull

public void restoreToNull()

Description copied from interface: Storable

Restore this object to its (SQL)null value.

Specified by:

restoreToNull in interface Storable

See Also:

• Storable.restoreToNull()

compare

public boolean compare(int op,
 DataValueDescriptor other,
 boolean orderedNulls,
 boolean unknownRV)
                throws StandardException

Description copied from interface: DataValueDescriptor

Compare this Orderable with a given Orderable for the purpose of qualification and sorting. The caller gets to determine how nulls should be treated - they can either be ordered values or unknown values.

Specified by:

compare in interface DataValueDescriptor

Overrides:

compare in class DataType

Parameters:

op - Orderable.ORDER_OP_EQUALS means do an = comparison. Orderable.ORDER_OP_LESSTHAN means compare this < other. Orderable.ORDER_OP_LESSOREQUALS means compare this <= other.

other - The DataValueDescriptor to compare this one to.

orderedNulls - True means to treat nulls as ordered values, that is, treat SQL null as equal to null, and less than all other values. False means to treat nulls as unknown values, that is, the result of any comparison with a null is the UNKNOWN truth value.

unknownRV - The return value to use if the result of the comparison is the UNKNOWN truth value. In other words, if orderedNulls is false, and a null is involved in the comparison, return unknownRV. This parameter is not used orderedNulls is true.

Returns:

true if the comparison is true (duh!)

Throws:

StandardException - Thrown on error

compare

public int compare(DataValueDescriptor other)
            throws StandardException

Description copied from interface: DataValueDescriptor

Compare this Orderable with a given Orderable for the purpose of index positioning. This method treats nulls as ordered values - that is, it treats SQL null as equal to null and greater than all other values.

Specified by:

compare in interface DataValueDescriptor

Parameters:

other - The Orderable to compare this one to.

Returns:

<0 - this Orderable is less than other. 0 - this Orderable equals other. >0 - this Orderable is greater than other. The code should not explicitly look for -1, or 1.

Throws:

StandardException - Thrown on error

cloneValue

public DataValueDescriptor cloneValue(boolean forceMaterialization)

Description copied from interface: DataValueDescriptor

Clone this DataValueDescriptor. Results in a new object that has the same value as this but can be modified independently.

Even though the objects can be modified independently regardless of the value of forceMaterialization, both the clone and the original may be dependent on the store state if forceMaterialization is set to false. An example is if you need to access the value you just read using cloneValue after the current transaction has ended, or after the source result set has been closed.

Specified by:

cloneValue in interface DataValueDescriptor

Parameters:

forceMaterialization - any streams representing the data value will be materialized if true, the data value will be kept as a stream if possible if false

Returns:

A clone of the DataValueDescriptor with the same initial value as this.

See Also:

• DataValueDescriptor.cloneValue(boolean)

getNewNull

public DataValueDescriptor getNewNull()

Description copied from interface: DataValueDescriptor

Get a new null value of the same type as this data value.

Specified by:

getNewNull in interface DataValueDescriptor

See Also:

• DataValueDescriptor.getNewNull()

setValueFromResultSet

public void setValueFromResultSet(ResultSet resultSet,
 int colNumber,
 boolean isNullable)

Description copied from interface: DataValueDescriptor

Set the value based on the value for the specified DataValueDescriptor from the specified ResultSet.

Specified by:

setValueFromResultSet in interface DataValueDescriptor

Parameters:

resultSet - The specified ResultSet.

colNumber - The 1-based column # into the resultSet.

isNullable - Whether or not the column is nullable (No need to call wasNull() if not)

See Also:

• DataValueDescriptor.setValueFromResultSet(ResultSet, int, boolean)

setInto

public void setInto(PreparedStatement ps,
 int position)

Description copied from interface: DataValueDescriptor

Set this value into a PreparedStatement. This method must handle setting NULL into the PreparedStatement.

Specified by:

setInto in interface DataValueDescriptor

Overrides:

setInto in class DataType

setValue

public void setValue(RowLocation rowLocation)

Description copied from interface: RefDataValue

Set the value of this RefDataValue.

Specified by:

setValue in interface RefDataValue

Parameters:

rowLocation - Contains the boolean value to set this RefDataValue to. Null means set this RefDataValue to null.

toString

public String toString()

Overrides:

toString in class Object

hashCode

public int hashCode()

Adding this overload makes it possible to use SQLRefs as keys in HashMaps.

Overrides:

hashCode in class Object