DBColumn (Apache Empire-db Core 2.5.1 API)

java.lang.Object
- org.apache.empire.db.DBObject
- - org.apache.empire.db.DBExpr
  - - org.apache.empire.db.DBColumnExpr
    - - org.apache.empire.db.DBColumn

All Implemented Interfaces:

Serializable, Column, ColumnExpr

Direct Known Subclasses:

DBCommandExpr.DBCmdColumn, DBQueryColumn, DBTableColumn, DBView.DBViewColumn
```
public abstract class DBColumn
extends DBColumnExpr
implements Column
```
This is the base class for all database columns that have a physical representation. i.e. either table or view columns (DBTableColumn oder DBViewColumn)
The column object describes a database column and thus provides metadata. Other non data model specific metadata may be added through attributes.

See Also:

DBTableColumn, DBView.DBViewColumn, Serialized Form

Field Summary

Fields
Modifier and Type	Field and Description
`protected String`	`comment`
`static String`	`DBCOLATTR_SINGLEBYTECHARS` Read only column (Boolean)
`protected String`	`name`
`protected DBRowSet`	`rowset`

Fields inherited from class org.apache.empire.db.DBColumnExpr
attributes, beanPropertyName, DBCOLATTR_TITLE, DBCOLATTR_TYPE, options

Fields inherited from class org.apache.empire.db.DBExpr
CTX_ALIAS, CTX_ALL, CTX_DEFAULT, CTX_FULLNAME, CTX_NAME, CTX_NOPARENTHESES, CTX_VALUE

Fields inherited from interface org.apache.empire.data.Column
COLATTR_CURRENCY_CODE, COLATTR_DATETIMEPATTERN, COLATTR_ENUMTYPE, COLATTR_FRACTION_DIGITS, COLATTR_INTEGER_DIGITS, COLATTR_MAXVALUE, COLATTR_MINLENGTH, COLATTR_MINVALUE, COLATTR_NUMBER_GROUPSEP, COLATTR_NUMBER_TYPE, COLATTR_REGEXP, COLATTR_TITLE, COLATTR_TOOLTIP, COLATTR_TYPE

Constructor Summary

Constructors
Modifier Constructor and Description

protected DBColumn(DBRowSet rowset, String name)
Constructs a DBColumn object and set the specified parameters to this object.

Constructors
Modifier	Constructor and Description
`protected`	`DBColumn(DBRowSet rowset, String name)` Constructs a DBColumn object and set the specified parameters to this object.

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Concrete Methods Deprecated Methods
Modifier and Type	Method and Description
`void`	`addReferencedColumns(Set<DBColumn> list)` Internal function to obtain all DBColumnExpr-objects used by this expression.
`void`	`addSQL(StringBuilder buf, long context)` Adds the colunm name to the SQL-Command.
`abstract Element`	`addXml(Element parent, long flags)` Add a description of this column with relevant metadata to the supplied parent XML Element.
`void`	`checkValue(Object value)` Deprecated. use validate() instead
`DBColumnExpr`	`decodeEnum()` Creates and returns a sql-expression that maps enum values by name or ordinal to their string representation
`DBColumnExpr`	`decodeSort(boolean defaultToEnd)` Creates and returns a sql-expression that maps enum values from name to ordinal
`boolean`	`equals(Object other)`
`static DBColumn`	`findById(String columnId)` returns a rowset by its identifier
`String`	`getAlias()` returns the qualified alias name for this column
`Object`	`getAttribute(String name)` Returns the value of a column attribute.
`String`	`getComment()` Returns a comment describing the column in the data scheme.
`DBDatabase`	`getDatabase()` Returns the database object to which this object belongs to.
`Class<Enum<?>>`	`getEnumType()` Returns the enum type for this column
`String`	`getFullName()` Returns the full qualified column name.
`String`	`getId()` Gets an identifier for this RowSet Object
`String`	`getName()` Returns the column name.
`Options`	`getOptions()` Returns the list of options for this column containing all possible field values.
`DBRowSet`	`getRowSet()` Returns DBTable, DBQuery or DBView object.
`abstract double`	`getSize()` Returns the size of the column.
`DBColumn`	`getUpdateColumn()` Returns this object.
`int`	`hashCode()`
`boolean`	`isAggregate()` Always returns false since DBColumns cannot be aggregates.
`abstract boolean`	`isAutoGenerated()` Returns true if column is a columns value is an automatically generated value
`boolean`	`isEnum()` Returns true if an enum type has been set for this column
`abstract boolean`	`isReadOnly()` Returns true if the column is read-only.
`abstract boolean`	`isRequired()` Returns true if the column is required.
`DBColumnExpr`	`qualified()` returns an expression that renames the column with its alias name
`void`	`setComment(String comment)` Sets a comment describing the current column.
`DBSetExpr`	`to(Object value)` Creates and returns a new DBSetExpr object.
`String`	`toString()` Override the toString method.
`abstract Object`	`validate(Object value)` Checks if the given value is a valid value for this column If not, an exception is thrown

Methods inherited from class org.apache.empire.db.DBColumnExpr
abs, append, as, as, asc, avg, ceiling, cmp, coalesce, convertTo, convertTo, count, countDistinct, day, decode, decode, decode, decode, decode, decode, decodeEnum, decodeSort, desc, divideBy, floor, format, getBeanPropertyName, getControlType, getDataType, getExprFromPhrase, getExprFromPhrase, getSourceColumn, getTitle, in, in, in, indexOf, indexOf, indexOf, is, isBetween, isGreaterThan, isLessOrEqual, isMoreOrEqual, isNot, isNotBetween, isSmallerThan, length, like, like, likeLower, likeUpper, lower, max, min, minus, minus, modulo, month, multiplyWith, notIn, notIn, notIn, notLike, nvl, parenthesis, plus, plus, replace, reverse, round, setAttribute, setBeanPropertyName, setControlType, setOptions, setTitle, substring, substring, substring, substring, substring, substring, sum, toChar, toChar, trim, trimLeft, trimRight, trunc, upper, when, year

Methods inherited from class org.apache.empire.db.DBExpr
getObjectValue, getValueClass

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

Methods inherited from interface org.apache.empire.data.ColumnExpr
getBeanPropertyName, getControlType, getDataType, getSourceColumn, getTitle

- Field Detail
  - DBCOLATTR_SINGLEBYTECHARS
```
public static final String DBCOLATTR_SINGLEBYTECHARS
```
    Read only column (Boolean)
    
    See Also:
    
    Constant Field Values
  - rowset
```
protected final transient DBRowSet rowset
```
  - name
```
protected final String name
```
  - comment
```
protected String comment
```
- Constructor Detail
  - DBColumn
```
protected DBColumn(DBRowSet rowset,
                   String name)
```
    Constructs a DBColumn object and set the specified parameters to this object.
    
    Parameters:
    
    rowset - the rowset (i.e. Table or View) that this column belongs to
    
    name - the column name
- Method Detail
  - getId
```
public String getId()
```
    Gets an identifier for this RowSet Object
    
    Returns:
    
    the rowset identifier
  - findById
```
public static DBColumn findById(String columnId)
```
    returns a rowset by its identifier
    
    Parameters:
    
    columnId - the id of the column
    
    Returns:
    
    the DBColumn object
  - equals
```
public boolean equals(Object other)
```
    Overrides:
    
    equals in class Object
  - hashCode
```
public int hashCode()
```
    Overrides:
    
    hashCode in class Object
  - getSize
```
public abstract double getSize()
```
    Returns the size of the column.
    
    Specified by:
    
    getSize in interface Column
    
    Returns:
    
    Returns the size of the column
  - isRequired
```
public abstract boolean isRequired()
```
    Returns true if the column is required.
    
    Specified by:
    
    isRequired in interface Column
    
    Returns:
    
    Returns true if the column is required
  - isAutoGenerated
```
public abstract boolean isAutoGenerated()
```
    Returns true if column is a columns value is an automatically generated value
    
    Specified by:
    
    isAutoGenerated in interface Column
    
    Returns:
    
    true if column is auto-generated
  - isReadOnly
```
public abstract boolean isReadOnly()
```
    Returns true if the column is read-only.
    
    Specified by:
    
    isReadOnly in interface Column
    
    Returns:
    
    Returns true if the column is read-only
  - validate
```
public abstract Object validate(Object value)
```
    Checks if the given value is a valid value for this column If not, an exception is thrown
    
    Specified by:
    
    validate in interface Column
    
    Returns:
    
    the value the validated and possibly converted value
  - checkValue
```
@Deprecated
public final void checkValue(Object value)
```
    Deprecated. use validate() instead
  - addXml
```
public abstract Element addXml(Element parent,
                               long flags)
```
    Description copied from class: DBColumnExpr
    
    Add a description of this column with relevant metadata to the supplied parent XML Element.
    
    Specified by:
    
    addXml in class DBColumnExpr
    
    Parameters:
    
    parent - the parent element to which to append the column description
    
    flags - currently not used
    
    Returns:
    
    the newly created child element
  - getDatabase
```
public DBDatabase getDatabase()
```
    Description copied from class: DBObject
    
    Returns the database object to which this object belongs to. For the database object itself this function will return the this pointer.
    
    Specified by:
    
    getDatabase in class DBObject
    
    Returns:
    
    the current DBDatabase object
  - addReferencedColumns
```
public void addReferencedColumns(Set<DBColumn> list)
```
    Description copied from class: DBExpr
    
    Internal function to obtain all DBColumnExpr-objects used by this expression.
    
    Specified by:
    
    addReferencedColumns in class DBExpr
    
    Parameters:
    
    list - list to which all used column expressions must be added
    
    See Also:
    
    DBExpr.addReferencedColumns(Set)
  - addSQL
```
public void addSQL(StringBuilder buf,
                   long context)
```
    Adds the colunm name to the SQL-Command.
    This can be either a qualified or unqualified name depending on the context.
    
    Specified by:
    
    addSQL in class DBExpr
    
    Parameters:
    
    buf - the SQL statment
    
    context - the current SQL-Command context
  - getUpdateColumn
```
public DBColumn getUpdateColumn()
```
    Returns this object.
    
    Specified by:
    
    getUpdateColumn in class DBColumnExpr
    
    Returns:
    
    this object
  - isAggregate
```
public boolean isAggregate()
```
    Always returns false since DBColumns cannot be aggregates.
    
    Specified by:
    
    isAggregate in class DBColumnExpr
    
    Returns:
    
    false
  - getRowSet
```
public DBRowSet getRowSet()
```
    Returns DBTable, DBQuery or DBView object.
    
    Returns:
    
    the DBTable, DBQuery or DBView object
  - getName
```
public String getName()
```
    Returns the column name.
    
    Specified by:
    
    getName in interface ColumnExpr
    
    Specified by:
    
    getName in class DBColumnExpr
    
    Returns:
    
    the column name
  - getFullName
```
public String getFullName()
```
    Returns the full qualified column name.
    
    Returns:
    
    the full qualified column name
  - getAlias
```
public String getAlias()
```
    returns the qualified alias name for this column
  - qualified
```
public DBColumnExpr qualified()
```
    returns an expression that renames the column with its alias name
  - getAttribute
```
public Object getAttribute(String name)
```
    Description copied from class: DBColumnExpr
    
    Returns the value of a column attribute. Column attributes are used to provide metadata for a column.
    
    Specified by:
    
    getAttribute in interface ColumnExpr
    
    Overrides:
    
    getAttribute in class DBColumnExpr
    
    Parameters:
    
    name - the attribute name
    
    Returns:
    
    value of the attribute if it exists or null otherwise
    
    See Also:
    
    DBColumnExpr.getAttribute(String)
  - getOptions
```
public Options getOptions()
```
    Description copied from class: DBColumnExpr
    
    Returns the list of options for this column containing all possible field values.
    
    Specified by:
    
    getOptions in interface ColumnExpr
    
    Overrides:
    
    getOptions in class DBColumnExpr
    
    Returns:
    
    the list of options
    
    See Also:
    
    DBColumnExpr.getOptions()
  - isEnum
```
public final boolean isEnum()
```
    Returns true if an enum type has been set for this column
    
    Returns:
    
    true if an enum type has been set for this column or false otherwise
  - getEnumType
```
public Class<Enum<?>> getEnumType()
```
    Returns the enum type for this column
    
    Specified by:
    
    getEnumType in interface Column
    
    Returns:
    
    the enum type
  - decodeEnum
```
public DBColumnExpr decodeEnum()
```
    Creates and returns a sql-expression that maps enum values by name or ordinal to their string representation
    
    Returns:
    
    a DBDecodeExpr object
  - decodeSort
```
public DBColumnExpr decodeSort(boolean defaultToEnd)
```
    Creates and returns a sql-expression that maps enum values from name to ordinal
    
    Returns:
    
    a DBDecodeExpr object
  - to
```
public DBSetExpr to(Object value)
```
    Creates and returns a new DBSetExpr object.
    
    Parameters:
    
    value - the Object value
    
    Returns:
    
    the new DBSetExpr object
    
    See Also:
    
    DBSetExpr
  - toString
```
public String toString()
```
    Override the toString method.
    
    Overrides:
    
    toString in class Object
    
    Returns:
    
    the table name and the column name (e.g. CUSTOMER.ID)
  - getComment
```
public String getComment()
```
    Returns a comment describing the column in the data scheme.
    
    Returns:
    
    Returns the comment.
  - setComment
```
public void setComment(String comment)
```
    Sets a comment describing the current column.
    
    Parameters:
    
    comment - the column comment

Class DBColumn

Field Summary

Fields inherited from class org.apache.empire.db.DBColumnExpr

Fields inherited from class org.apache.empire.db.DBExpr

Fields inherited from interface org.apache.empire.data.Column

Constructor Summary

Method Summary

Methods inherited from class org.apache.empire.db.DBColumnExpr

Methods inherited from class org.apache.empire.db.DBExpr

Methods inherited from class java.lang.Object

Methods inherited from interface org.apache.empire.data.ColumnExpr

Field Detail

DBCOLATTR_SINGLEBYTECHARS

rowset

name

comment

Constructor Detail

DBColumn

Method Detail

getId

findById

equals

hashCode

getSize

isRequired

isAutoGenerated

isReadOnly

validate

checkValue

addXml

getDatabase

addReferencedColumns

addSQL

getUpdateColumn

isAggregate

getRowSet

getName

getFullName

getAlias

qualified

getAttribute

getOptions

isEnum

getEnumType

decodeEnum

decodeSort

to

toString

getComment

setComment