GenericColumnDescriptor (Apache Derby V10.10 Internals)

java.lang.Object
- org.apache.derby.impl.sql.GenericColumnDescriptor

All Implemented Interfaces:

java.io.Externalizable, java.io.Serializable, Formatable, TypedFormat, ResultColumnDescriptor
```
public final class GenericColumnDescriptor
extends java.lang.Object
implements ResultColumnDescriptor, Formatable
```
This is a stripped down implementation of a column descriptor that is intended for generic use. It can be seralized and attached to plans.

See Also:

Serialized Form

Field Summary

Fields
Modifier and Type	Field and Description
`private int`	`columnPos`
`private boolean`	`hasGenerationClause`
`private boolean`	`isAutoincrement`
`private java.lang.String`	`name` This class implements Formatable.
`private java.lang.String`	`schemaName`
`private java.lang.String`	`tableName`
`private DataTypeDescriptor`	`type`
`private boolean`	`updatableByCursor`

Constructor Summary

Constructors
Constructor and Description
`GenericColumnDescriptor()` Niladic constructor for Formatable
`GenericColumnDescriptor(ResultColumnDescriptor rcd)` This constructor is used to build a generic (and formatable) ColumnDescriptor.
`GenericColumnDescriptor(java.lang.String name, DataTypeDescriptor type)`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`int`	`getColumnPosition()` Get the position of the Column.
`java.lang.String`	`getName()` Returns the name of the Column.
`java.lang.String`	`getSourceSchemaName()` Get the name of the schema for the Column's base table, if any.
`java.lang.String`	`getSourceTableName()` Get the name of the underlying(base) table this column comes from, if any.
`private DataTypeDescriptor`	`getStoredDataTypeDescriptor(java.lang.Object o)` When retrieving a DataTypeDescriptor, it might just be a regular DataTypeDescriptor or may be an OldRoutineType, as used for Routine parameters and return values prior to DERBY-2775.
`DataTypeDescriptor`	`getType()` Returns a DataTypeDescriptor for the column.
`int`	`getTypeFormatId()` Get the formatID which corresponds to this class.
`boolean`	`hasGenerationClause()` Return true if this result column represents a generated column.
`boolean`	`isAutoincrement()` Tell us if the column is an autoincrement column or not.
`void`	`readExternal(java.io.ObjectInput in)` Read this object from a stream of stored objects.
`java.lang.String`	`toString()`
`boolean`	`updatableByCursor()` Return true if the column is wirtable by a positioned update.
`void`	`writeExternal(java.io.ObjectOutput out)` Write this object out

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Field Detail
  - name
```
private java.lang.String name
```
    This class implements Formatable. That means that it can write itself to and from a formatted stream. If you add more fields to this class, make sure that you also write/read them with the writeExternal()/readExternal() methods. If, inbetween releases, you add more fields to this class, then you should bump the version number emitted by the getTypeFormatId() method.
  - schemaName
```
private java.lang.String schemaName
```
  - tableName
```
private java.lang.String tableName
```
  - columnPos
```
private int columnPos
```
  - type
```
private DataTypeDescriptor type
```
  - isAutoincrement
```
private boolean isAutoincrement
```
  - updatableByCursor
```
private boolean updatableByCursor
```
  - hasGenerationClause
```
private boolean hasGenerationClause
```
- Constructor Detail
  - GenericColumnDescriptor
```
public GenericColumnDescriptor()
```
    Niladic constructor for Formatable
  - GenericColumnDescriptor
```
public GenericColumnDescriptor(java.lang.String name,
                               DataTypeDescriptor type)
```
  - GenericColumnDescriptor
```
public GenericColumnDescriptor(ResultColumnDescriptor rcd)
```
    This constructor is used to build a generic (and formatable) ColumnDescriptor. The idea is that it can be passed a ColumnDescriptor from a query tree and convert it to something that can be used anywhere.
    
    Parameters:
    
    rcd - the ResultColumnDescriptor
- Method Detail
  - getType
```
public DataTypeDescriptor getType()
```
    Returns a DataTypeDescriptor for the column. This DataTypeDescriptor will not represent an actual value, it will only represent the type that all values in the column will have.
    
    Specified by:
    
    getType in interface ResultColumnDescriptor
    
    Returns:
    
    A DataTypeDescriptor describing the type of the column.
  - getName
```
public java.lang.String getName()
```
    Returns the name of the Column.
    
    Specified by:
    
    getName in interface ResultColumnDescriptor
    
    Returns:
    
    A String containing the name of the column.
  - getSourceSchemaName
```
public java.lang.String getSourceSchemaName()
```
    Get the name of the schema for the Column's base table, if any. Following example queries will all return APP (assuming user is in schema APP) select t.a from t select b.a from t as b select app.t.a from t
    
    Specified by:
    
    getSourceSchemaName in interface ResultColumnDescriptor
    
    Returns:
    
    A String containing the name of the schema of the Column's table. If the column is not in a schema (i.e. is a derived column), it returns NULL.
  - getSourceTableName
```
public java.lang.String getSourceTableName()
```
    Get the name of the underlying(base) table this column comes from, if any. Following example queries will all return T select a from t select b.a from t as b select t.a from t
    
    Specified by:
    
    getSourceTableName in interface ResultColumnDescriptor
    
    Returns:
    
    A String containing the name of the Column's base table. If the column is not in a table (i.e. is a derived column), it returns NULL.
  - getColumnPosition
```
public int getColumnPosition()
```
    Get the position of the Column. NOTE - position is 1-based.
    
    Specified by:
    
    getColumnPosition in interface ResultColumnDescriptor
    
    Returns:
    
    An int containing the position of the Column within the table.
  - isAutoincrement
```
public boolean isAutoincrement()
```
    Description copied from interface: ResultColumnDescriptor
    
    Tell us if the column is an autoincrement column or not.
    
    Specified by:
    
    isAutoincrement in interface ResultColumnDescriptor
    
    Returns:
    
    TRUE, if the column is a base column of a table and is an autoincrement column.
  - updatableByCursor
```
public boolean updatableByCursor()
```
    Description copied from interface: ResultColumnDescriptor
    
    Return true if the column is wirtable by a positioned update.
    
    Specified by:
    
    updatableByCursor in interface ResultColumnDescriptor
    
    Returns:
    
    TRUE, if the column is a base column of a table and is writable by a positioned update.
  - hasGenerationClause
```
public boolean hasGenerationClause()
```
    Description copied from interface: ResultColumnDescriptor
    
    Return true if this result column represents a generated column.
    
    Specified by:
    
    hasGenerationClause in interface ResultColumnDescriptor
  - writeExternal
```
public void writeExternal(java.io.ObjectOutput out)
                   throws java.io.IOException
```
    Write this object out
    
    Specified by:
    
    writeExternal in interface java.io.Externalizable
    
    Parameters:
    
    out - write bytes here
    
    Throws:
    
    java.io.IOException - thrown on error
  - readExternal
```
public void readExternal(java.io.ObjectInput in)
                  throws java.io.IOException,
                         java.lang.ClassNotFoundException
```
    Read this object from a stream of stored objects.
    
    Specified by:
    
    readExternal in interface java.io.Externalizable
    
    Parameters:
    
    in - read this.
    
    Throws:
    
    java.io.IOException - thrown on error
    
    java.lang.ClassNotFoundException - thrown on error
  - getTypeFormatId
```
public int getTypeFormatId()
```
    Get the formatID which corresponds to this class.
    
    Specified by:
    
    getTypeFormatId in interface TypedFormat
    
    Returns:
    
    the formatID of this class
  - toString
```
public java.lang.String toString()
```
    Overrides:
    
    toString in class java.lang.Object
  - getStoredDataTypeDescriptor
```
private DataTypeDescriptor getStoredDataTypeDescriptor(java.lang.Object o)
```
    When retrieving a DataTypeDescriptor, it might just be a regular DataTypeDescriptor or may be an OldRoutineType, as used for Routine parameters and return values prior to DERBY-2775. If it is not a regular DataTypeDescriptor, it must be an OldRoutineType, so convert it to a DataTypeDescriptor DERBY-4913
    
    Parameters:
    
    o - object as obtained by fh.get("type") in readExternal
    
    Returns:
    
    DataTypeDescriptor

Class GenericColumnDescriptor

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

name

schemaName

tableName

columnPos

type

isAutoincrement

updatableByCursor

hasGenerationClause

Constructor Detail

GenericColumnDescriptor

GenericColumnDescriptor

GenericColumnDescriptor

Method Detail

getType

getName

getSourceSchemaName

getSourceTableName

getColumnPosition

isAutoincrement

updatableByCursor

hasGenerationClause

writeExternal

readExternal

getTypeFormatId

toString

getStoredDataTypeDescriptor