org.apache.derby.catalog
Interface TypeDescriptor

All Known Implementing Classes:

DataTypeDescriptor, TypeDescriptorImpl

public interface TypeDescriptor

An interface for describing types in Cloudscape systems.

The values in system catalog DATATYPE columns are of type TypeDescriptor.

Field Summary

static int

MAXIMUM_WIDTH_UNKNOWN The return value from getMaximumWidth() for types where the maximum width is unknown.

Method Summary

int	getJDBCTypeId() Get the jdbc type id for this type.
int	getMaximumWidth() Returns the maximum width of the type.
int	getMaximumWidthInBytes() Returns the maximum width of the type IN BYTES.
int	getPrecision() Returns the number of decimal digits for the type, if applicable.
int	getScale() Returns the number of digits to the right of the decimal for the type, if applicable.
java.lang.String	getSQLstring() Converts this type descriptor (including length/precision) to a string suitable for appearing in a SQL type specifier.
java.lang.String	getTypeName() Gets the name of this type.
boolean	isNullable() Gets the nullability that values of this type have.

Field Detail

MAXIMUM_WIDTH_UNKNOWN

public static final int MAXIMUM_WIDTH_UNKNOWN

The return value from getMaximumWidth() for types where the maximum width is unknown.

See Also:

Constant Field Values

Method Detail

getJDBCTypeId

public int getJDBCTypeId()

Get the jdbc type id for this type. JDBC type can be found in java.sql.Types.

Returns:

a jdbc type, e.g. java.sql.Types.DECIMAL

See Also:

Types

getMaximumWidth

public int getMaximumWidth()

Returns the maximum width of the type. This may have different meanings for different types. For example, with char, it means the maximum number of characters, while with int, it is the number of bytes (i.e. 4).

Returns:

the maximum length of this Type; -1 means "unknown/no max length"

getMaximumWidthInBytes

public int getMaximumWidthInBytes()

Returns the maximum width of the type IN BYTES. This is the maximum number of bytes that could be returned for this type if the corresponding getXXX() method is used. For example, if we have a CHAR type, then we want the number of bytes that would be returned by a ResultSet.getString() call.

Returns:

the maximum length of this Type IN BYTES; -1 means "unknown/no max length"

getPrecision

public int getPrecision()

Returns the number of decimal digits for the type, if applicable.

Returns:

The number of decimal digits for the type. Returns zero for non-numeric types.

getScale

public int getScale()

Returns the number of digits to the right of the decimal for the type, if applicable.

Returns:

The number of digits to the right of the decimal for the type. Returns zero for non-numeric types.

isNullable

public boolean isNullable()

Gets the nullability that values of this type have.

Returns:

true if values of this type may be null. false otherwise

getTypeName

public java.lang.String getTypeName()

Gets the name of this type.

Returns:

the name of this type

getSQLstring

public java.lang.String getSQLstring()

Converts this type descriptor (including length/precision) to a string suitable for appearing in a SQL type specifier. E.g. VARCHAR(30) or java.util.Hashtable

Returns:

String version of type, suitable for running through a SQL Parser.