Class EmbedResultSetMetaData

java.lang.Object

org.apache.derby.impl.jdbc.EmbedResultSetMetaData

All Implemented Interfaces:

ResultSetMetaData, Wrapper

public class EmbedResultSetMetaData
extends Object
implements ResultSetMetaData

A ResultSetMetaData object can be used to find out about the types and properties of the columns in a ResultSet.

We take the (Derby) ResultDescription and examine it, to return the appropriate information.

This class can be used outside of this package to convert a ResultDescription into a ResultSetMetaData object.

EmbedResultSetMetaData objects are shared across multiple threads by being stored in the ResultDescription for a compiled plan. If the required api for ResultSetMetaData ever changes so that it has a close() method, a getConnection() method or any other Connection or ResultSet specific method then this sharing must be removed.

Field Summary

Fields

Modifier and Type	Field	Description
private final ResultColumnDescriptor[]	columnInfo

Fields inherited from interface ResultSetMetaData

columnNoNulls, columnNullable, columnNullableUnknown

Constructor Summary

Constructors

Constructor	Description
EmbedResultSetMetaData(ResultColumnDescriptor[] columnInfo)

Method Summary

Modifier and Type	Method	Description
final String	getCatalogName(int column)	What's a column's table's catalog name?
final String	getColumnClassName(int column)	JDBC 2.0
final int	getColumnCount()	What's the number of columns in the ResultSet?
final int	getColumnDisplaySize(int column)	What's the column's normal max width in chars?
final String	getColumnLabel(int column)	What's the suggested column title for use in printouts and displays?
final String	getColumnName(int column)	What's a column's name?
final int	getColumnType(int column)	What's a column's SQL type?
private DataTypeDescriptor	getColumnTypeDescriptor(int column)
final String	getColumnTypeName(int column)	What's a column's data source specific type name?
final int	getPrecision(int column)	What's a column's number of decimal digits?
static ResultColumnDescriptor	getResultColumnDescriptor(String name, int jdcbTypeId, boolean nullable)
static ResultColumnDescriptor	getResultColumnDescriptor(String name, int jdcbTypeId, boolean nullable, int length)
static ResultColumnDescriptor	getResultColumnDescriptor(String name, DataTypeDescriptor dtd)
final int	getScale(int column)	What's a column's number of digits to right of the decimal point?
final String	getSchemaName(int column)	What's a column's table's schema?
final String	getTableName(int column)	What's a column's table name?
final boolean	isAutoIncrement(int column)	Is the column automatically numbered, thus read-only?
final boolean	isCaseSensitive(int column)	Does a column's case matter?
final boolean	isCurrency(int column)	Is the column a cash value?
final boolean	isDefinitelyWritable(int column)	Will a write on the column definitely succeed?
final int	isNullable(int column)	Can you put a NULL in this column?
final boolean	isReadOnly(int column)	Is a column definitely not writable?
final boolean	isSearchable(int column)	Can the column be used in a where clause?
final boolean	isSigned(int column)	Is the column a signed number?
final boolean	isWrapperFor(Class<?> iface)	Returns whether or not this instance implements the specified interface.
final boolean	isWritable(int column)	Is it possible for a write on the column to succeed?
final <T> T	unwrap(Class<T> iface)	Returns this if this class implements the interface.
private void	validColumnNumber(int column)

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

columnInfo

private final ResultColumnDescriptor[] columnInfo

Constructor Details

EmbedResultSetMetaData

public EmbedResultSetMetaData(ResultColumnDescriptor[] columnInfo)

Method Details

getColumnCount

public final int getColumnCount()

What's the number of columns in the ResultSet?

Specified by:

getColumnCount in interface ResultSetMetaData

Returns:

the number

isAutoIncrement

public final boolean isAutoIncrement(int column)
                              throws SQLException

Is the column automatically numbered, thus read-only?

Specified by:

isAutoIncrement in interface ResultSetMetaData

Parameters:

column - the first column is 1, the second is 2, ...

Returns:

true if so

Throws:

SQLException - thrown on failure

isCaseSensitive

public final boolean isCaseSensitive(int column)
                              throws SQLException

Does a column's case matter?

Specified by:

isCaseSensitive in interface ResultSetMetaData

Parameters:

column - the first column is 1, the second is 2, ...

Returns:

true if so

Throws:

SQLException - thrown on failure

isSearchable

public final boolean isSearchable(int column)
                           throws SQLException

Can the column be used in a where clause?

Specified by:

isSearchable in interface ResultSetMetaData

Parameters:

column - the first column is 1, the second is 2, ...

Returns:

true if so

Throws:

SQLException - thrown on failure

isCurrency

public final boolean isCurrency(int column)
                         throws SQLException

Is the column a cash value? Always returns false since there are no currency data types in Derby.

Specified by:

isCurrency in interface ResultSetMetaData

Parameters:

column - the first column is 1, the second is 2, ...

Returns:

false, always

Throws:

SQLException - thrown on failure

isNullable

public final int isNullable(int column)
                     throws SQLException

Can you put a NULL in this column?

Specified by:

isNullable in interface ResultSetMetaData

Parameters:

column - the first column is 1, the second is 2, ...

Returns:

columnNoNulls, columnNullable or columnNullableUnknown

Throws:

SQLException - thrown on failure

isSigned

public final boolean isSigned(int column)
                       throws SQLException

Is the column a signed number?

Specified by:

isSigned in interface ResultSetMetaData

Parameters:

column - the first column is 1, the second is 2, ...

Returns:

true if so

Throws:

SQLException - thrown on failure

getColumnDisplaySize

public final int getColumnDisplaySize(int column)
                               throws SQLException

What's the column's normal max width in chars?

Specified by:

getColumnDisplaySize in interface ResultSetMetaData

Parameters:

column - the first column is 1, the second is 2, ...

Returns:

max width

Throws:

SQLException - thrown on failure

getColumnLabel

public final String getColumnLabel(int column)
                            throws SQLException

What's the suggested column title for use in printouts and displays?

Specified by:

getColumnLabel in interface ResultSetMetaData

Parameters:

column - the first column is 1, the second is 2, ...

Returns:

true if so

Throws:

SQLException - thrown on failure

getColumnName

public final String getColumnName(int column)
                           throws SQLException

What's a column's name?

Specified by:

getColumnName in interface ResultSetMetaData

Parameters:

column - the first column is 1, the second is 2, ...

Returns:

column name

Throws:

SQLException - thrown on failure

getSchemaName

public final String getSchemaName(int column)
                           throws SQLException

What's a column's table's schema?

Specified by:

getSchemaName in interface ResultSetMetaData

Parameters:

column - the first column is 1, the second is 2, ...

Returns:

schema name or "" if not applicable

Throws:

SQLException - thrown on failure

getPrecision

public final int getPrecision(int column)
                       throws SQLException

What's a column's number of decimal digits?

Specified by:

getPrecision in interface ResultSetMetaData

Parameters:

column - the first column is 1, the second is 2, ...

Returns:

precision

Throws:

SQLException - thrown on failure

getScale

public final int getScale(int column)
                   throws SQLException

What's a column's number of digits to right of the decimal point?

Specified by:

getScale in interface ResultSetMetaData

Parameters:

column - the first column is 1, the second is 2, ...

Returns:

scale

Throws:

SQLException - thrown on failure

getTableName

public final String getTableName(int column)
                          throws SQLException

What's a column's table name?

Specified by:

getTableName in interface ResultSetMetaData

Returns:

table name or "" if not applicable

Throws:

SQLException - thrown on failure

getCatalogName

public final String getCatalogName(int column)
                            throws SQLException

What's a column's table's catalog name?

Specified by:

getCatalogName in interface ResultSetMetaData

Parameters:

column - the first column is 1, the second is 2, ...

Returns:

column name or "" if not applicable.

Throws:

SQLException - thrown on failure

getColumnType

public final int getColumnType(int column)
                        throws SQLException

What's a column's SQL type?

Specified by:

getColumnType in interface ResultSetMetaData

Parameters:

column - the first column is 1, the second is 2, ...

Returns:

SQL type

Throws:

SQLException - thrown on failure

See Also:

• Types

getColumnTypeName

public final String getColumnTypeName(int column)
                               throws SQLException

What's a column's data source specific type name?

Specified by:

getColumnTypeName in interface ResultSetMetaData

Parameters:

column - the first column is 1, the second is 2, ...

Returns:

type name

Throws:

SQLException - thrown on failure

isReadOnly

public final boolean isReadOnly(int column)
                         throws SQLException

Is a column definitely not writable?

Specified by:

isReadOnly in interface ResultSetMetaData

Parameters:

column - the first column is 1, the second is 2, ...

Returns:

true if so

Throws:

SQLException - thrown on failure

isWritable

public final boolean isWritable(int column)
                         throws SQLException

Is it possible for a write on the column to succeed?

Specified by:

isWritable in interface ResultSetMetaData

Parameters:

column - the first column is 1, the second is 2, ...

Returns:

true if so

Throws:

SQLException - thrown on failure

isDefinitelyWritable

public final boolean isDefinitelyWritable(int column)
                                   throws SQLException

Will a write on the column definitely succeed?

Specified by:

isDefinitelyWritable in interface ResultSetMetaData

Parameters:

column - the first column is 1, the second is 2, ...

Returns:

true if so

Throws:

SQLException - thrown on failure

validColumnNumber

private void validColumnNumber(int column)
                        throws SQLException

Throws:

SQLException

getColumnTypeDescriptor

private DataTypeDescriptor getColumnTypeDescriptor(int column)
                                            throws SQLException

Throws:

SQLException

getColumnClassName

public final String getColumnClassName(int column)
                                throws SQLException

JDBC 2.0

Return the fully qualified name of the Java class whose instances are manufactured if ResultSet.getObject() is called to retrieve a value from the column. ResultSet.getObject() may return a subClass of the class returned by this method.

Specified by:

getColumnClassName in interface ResultSetMetaData

Throws:

SQLException - Feature not inplemented for now.

getResultColumnDescriptor

public static ResultColumnDescriptor getResultColumnDescriptor(String name,
 int jdcbTypeId,
 boolean nullable)

getResultColumnDescriptor

public static ResultColumnDescriptor getResultColumnDescriptor(String name,
 int jdcbTypeId,
 boolean nullable,
 int length)

getResultColumnDescriptor

public static ResultColumnDescriptor getResultColumnDescriptor(String name,
 DataTypeDescriptor dtd)

isWrapperFor

public final boolean isWrapperFor(Class<?> iface)

Returns whether or not this instance implements the specified interface.

Specified by:

isWrapperFor in interface Wrapper

Parameters:

iface - the interface to check for

Returns:

true if this implements the interface

unwrap

public final <T> T unwrap(Class<T> iface)
                   throws SQLException

Returns this if this class implements the interface.

Specified by:

unwrap in interface Wrapper

Parameters:

iface - the interface

Returns:

an object that implements the interface

Throws:

SQLException - if no object is found that implements the interface