java.lang.Object
org.apache.derby.iapi.types.DataType
org.apache.derby.iapi.types.SQLBinary
org.apache.derby.iapi.types.SQLBit
- All Implemented Interfaces:
- BitDataValue, CloneableObject, ConcatableDataValue, DataValueDescriptor, java.io.Externalizable, org.apache.derby.iapi.services.io.Formatable, Orderable, java.io.Serializable, org.apache.derby.iapi.services.io.Storable, org.apache.derby.iapi.services.io.StreamStorable, org.apache.derby.iapi.services.io.TypedFormat, VariableSizeDataValue
- Direct Known Subclasses:
- SQLVarbit
- public class SQLBit
- extends SQLBinary
SQLBit satisfies the DataValueDescriptor
interfaces (i.e., DataType). It implements a String holder,
e.g. for storing a column value; it can be specified
when constructed to not allow nulls. Nullability cannot be changed
after construction.
Because DataType is a subclass of DataType,
SQLBit can play a role in either a DataType/Value
or a DataType/KeyRow, interchangeably.
Format :
Length is encoded to support 5.x databases where the length was stored as the number of bits.
The first bit of the first byte indicates if the format is an old (5.x) style or a new 8.1 style.
8.1 then uses the next two bits to indicate how the length is encoded.
is one of N styles.
- (5.x format) 4 byte Java format integer value 0 - either is 0 bytes/bits or an unknown number of bytes.
- (5.x format) 4 byte Java format integer value >0 (positive) - number of bits in , number of bytes in
is the minimum number of bytes required to store the number of bits.
- (8.1 format) 1 byte encoded length (0 <= L <= 31) - number of bytes of - encoded = 0x80 & L
- (8.1 format) 3 byte encoded length (32 <= L < 64k) - number of bytes of - encoded = 0xA0
- (8.1 format) 5 byte encoded length (64k <= L < 2G) - number of bytes of - encoded = 0xC0
- (future) to be determined L >= 2G - encoded 0xE0
(0xE0 is an esacape to allow any number of arbitary encodings in the future).
|
Constructor Summary |
SQLBit()
no-arg constructor, required by Formattable. |
SQLBit(byte[] val)
|
| Methods inherited from class org.apache.derby.iapi.types.SQLBinary |
charLength, checkHostVariable, cloneObject, compare, compare, concatenate, equals, estimateMemoryUsage, getBytes, getClone, getLength, getStream, getString, getValue, greaterOrEquals, greaterThan, hashCode, isNull, lessOrEquals, lessThan, loadStream, notEquals, objectNull, readExternal, readExternalFromArray, restoreToNull, returnStream, setFrom, setInto, setStream, setValue, setValue, substring, toString, writeExternal |
| Methods inherited from class org.apache.derby.iapi.types.DataType |
coalesce, dataTypeConversion, equals, flip, genericSetObject, getBoolean, getByte, getDate, getDouble, getFloat, getInt, getLong, getNationalString, getShort, getTime, getTimestamp, in, invalidFormat, isNotNull, isNullOp, outOfRange, setBigDecimal, setInto, setObjectForCast, setToNull, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, throwLangSetMismatch, throwLangSetMismatch, typeToBigDecimal |
| Methods inherited from interface org.apache.derby.iapi.types.DataValueDescriptor |
coalesce, getBoolean, getByte, getDate, getDouble, getFloat, getInt, getLong, getShort, getTime, getTimestamp, in, isNotNull, isNullOp, setBigDecimal, setInto, setObjectForCast, setToNull, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, typeToBigDecimal |
SQLBit
public SQLBit()
- no-arg constructor, required by Formattable.
SQLBit
public SQLBit(byte[] val)
getObject
public java.lang.Object getObject()
throws org.apache.derby.iapi.error.StandardException
- Description copied from interface:
DataValueDescriptor
- Gets the value in the data value descriptor as a Java Object.
The type of the Object will be the Java object type corresponding
to the data value's SQL type. JDBC defines a mapping between Java
object types and SQL types - we will allow that to be extended
through user type definitions. Throws an exception if the data
value is not an object (yeah, right).
- Specified by:
getObject in interface DataValueDescriptor- Overrides:
getObject in class DataType
getTypeName
public java.lang.String getTypeName()
- Description copied from interface:
DataValueDescriptor
- Get the SQL name of the datatype
getTypeFormatId
public int getTypeFormatId()
- Return my format identifier.
getNewNull
public DataValueDescriptor getNewNull()
- Description copied from interface:
DataValueDescriptor
- Get a new null value of the same type as this data value.
setValueFromResultSet
public void setValueFromResultSet(java.sql.ResultSet resultSet,
int colNumber,
boolean isNullable)
throws java.sql.SQLException
- Description copied from interface:
DataValueDescriptor
- Set the value based on the value for the specified DataValueDescriptor
from the specified ResultSet.
typePrecedence
public int typePrecedence()
- Description copied from interface:
DataValueDescriptor
- Each built-in type in JSQL has a precedence. This precedence determines
how to do type promotion when using binary operators. For example, float
has a higher precedence than int, so when adding an int to a float, the
result type is float.
The precedence for some types is arbitrary. For example, it doesn't
matter what the precedence of the boolean type is, since it can't be
mixed with other types. But the precedence for the number types is
critical. The SQL standard requires that exact numeric types be
promoted to approximate numeric when one operator uses both. Also,
the precedence is arranged so that one will not lose precision when
promoting a type.
- Specified by:
typePrecedence in interface DataValueDescriptor- Overrides:
typePrecedence in class DataType
setValue
public final void setValue(java.lang.Object theValue)
throws org.apache.derby.iapi.error.StandardException
- Description copied from interface:
DataValueDescriptor
- Set the value of this DataValueDescriptor to the given value
- Specified by:
setValue in interface DataValueDescriptor- Overrides:
setValue in class DataType
normalize
public void normalize(DataTypeDescriptor desiredType,
DataValueDescriptor source)
throws org.apache.derby.iapi.error.StandardException
- Normalization method - this method may be called when putting
a value into a SQLBit, for example, when inserting into a SQLBit
column. See NormalizeResultSet in execution.
- Specified by:
normalize in interface DataValueDescriptor- Overrides:
normalize in class DataType
setWidth
public DataValueDescriptor setWidth(int desiredWidth,
int desiredScale,
boolean errorOnTrunc)
throws org.apache.derby.iapi.error.StandardException
- Set the width of the to the desired value. Used
when CASTing. Ideally we'd recycle normalize(), but
the behavior is different (we issue a warning instead
of an error, and we aren't interested in nullability).
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