embedresultsetmetadata.java

derby database source code.good for you.

/*

   Derby - Class org.apache.derby.impl.jdbc.EmbedResultSetMetaData

   Copyright 1997, 2004 The Apache Software Foundation or its licensors, as applicable.

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.

 */

package org.apache.derby.impl.jdbc;

import org.apache.derby.iapi.sql.ResultDescription;
import org.apache.derby.iapi.sql.ResultColumnDescriptor;
import org.apache.derby.iapi.types.DataTypeDescriptor;
import org.apache.derby.iapi.types.DataTypeUtilities;
import org.apache.derby.iapi.types.TypeId;

import org.apache.derby.iapi.services.sanity.SanityManager;

import org.apache.derby.iapi.reference.SQLState;

import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Types;
import java.sql.ResultSet;

/**
 * A ResultSetMetaData object can be used to find out about the types
 * and properties of the columns in a ResultSet.
 *
 * <p>
 * We take the (cloudscape) ResultDescription and examine it, to return
 * the appropriate information.

   <P>
   This class can be used outside of this package to convert a
   ResultDescription into a ResultSetMetaData object.
 *
 * @author ames
 */
public class EmbedResultSetMetaData
	implements ResultSetMetaData {

	private final ResultColumnDescriptor[] columnInfo;

	//
	// constructor
	//
	public EmbedResultSetMetaData(ResultColumnDescriptor[] columnInfo) {
		this.columnInfo = columnInfo;
	}

	//
	// ResultSetMetaData interface
	//

    /**
     * What's the number of columns in the ResultSet?
     *
     * @return the number
     */
	public int getColumnCount()	{
		return columnInfo == null ? 0 : columnInfo.length;
	}

    /**
     * Is the column automatically numbered, thus read-only?
     *
     * @param column the first column is 1, the second is 2, ...
     * @return true if so
	 * @exception SQLException thrown on failure
     *
     */
	public boolean isAutoIncrement(int column) throws SQLException	{

		ResultColumnDescriptor rcd = columnInfo[column - 1];
		return rcd.isAutoincrement();
	}

    /**
     * Does a column's case matter?
     *
     * @param column the first column is 1, the second is 2, ...
     * @return true if so
	 * @exception SQLException thrown on failure
     */
	public boolean isCaseSensitive(int column) throws SQLException	{
	  return DataTypeUtilities.isCaseSensitive(getColumnTypeDescriptor(column));
	}


    /**
     * Can the column be used in a where clause?
     *
     * @param column the first column is 1, the second is 2, ...
     * @return true if so
	 * @exception SQLException thrown on failure
     */
	public boolean isSearchable(int column) throws SQLException	{
		validColumnNumber(column);

		// we have no restrictions yet, so this is always true
		// might eventually be false for e.g. extra-long columns?
		return true;
	}

    /**
     * Is the column a cash value?
     *
     * @param column the first column is 1, the second is 2, ...
     * @return true if so
	 * @exception SQLException thrown on failure
     */
	public boolean isCurrency(int column) throws SQLException	{

		return DataTypeUtilities.isCurrency(getColumnTypeDescriptor(column));
	}

    /**
     * Can you put a NULL in this column?
     *
     * @param column the first column is 1, the second is 2, ...
     * @return columnNoNulls, columnNullable or columnNullableUnknown
	 * @exception SQLException thrown on failure
     */
	public int isNullable(int column) throws SQLException	{
		return DataTypeUtilities.isNullable(getColumnTypeDescriptor(column));
	}

    /**
     * Is the column a signed number?
     *
     * @param column the first column is 1, the second is 2, ...
     * @return true if so
	 * @exception SQLException thrown on failure
     */
	public boolean isSigned(int column) throws SQLException	{
		return DataTypeUtilities.isSigned(getColumnTypeDescriptor(column));
	}


    /**
     * What's the column's normal max width in chars?
     *
     * @param column the first column is 1, the second is 2, ...
     * @return max width
	 * @exception SQLException thrown on failure
     */
	public int getColumnDisplaySize(int column) throws SQLException	{
		return DataTypeUtilities.getColumnDisplaySize(getColumnTypeDescriptor(column));
	}

    /**
     * What's the suggested column title for use in printouts and
     * displays?
     *
     * @param column the first column is 1, the second is 2, ...
     * @return true if so
	 * @exception SQLException thrown on failure
     */
	public String getColumnLabel(int column) throws SQLException {
		ResultColumnDescriptor cd = columnInfo[column - 1];
		String s = cd.getName();

		// we could get fancier than this, but it's simple
    	return (s==null? "Column"+Integer.toString(column) : s);
	}


    /**
     * What's a column's name?
     *
     * @param column the first column is 1, the second is 2, ...
     * @return column name
	 * @exception SQLException thrown on failure
     */
	public String getColumnName(int column) throws SQLException	{
		ResultColumnDescriptor cd = columnInfo[column - 1];
		String s = cd.getName();
		// database returns null when no column name to differentiate from empty name
    	return (s==null? "" : s);

	}


    /**
     * What's a column's table's schema?
     *
     * @param column the first column is 1, the second is 2, ...
     * @return schema name or "" if not applicable
	 * @exception SQLException thrown on failure
     */
	public String getSchemaName(int column) throws SQLException	{
		ResultColumnDescriptor cd = columnInfo[column - 1];

		String s = cd.getSourceSchemaName();
		// database returns null when no schema name to differentiate from empty name
		return (s==null? "" : s);
	}

    /**
     * What's a column's number of decimal digits?
     *
     * @param column the first column is 1, the second is 2, ...
     * @return precision
	 * @exception SQLException thrown on failure
     */
	public int getPrecision(int column) throws SQLException	{
		return DataTypeUtilities.getDigitPrecision(getColumnTypeDescriptor(column));
	}


    /**
     * What's a column's number of digits to right of the decimal point?
     *
     * @param column the first column is 1, the second is 2, ...
     * @return scale
	 * @exception SQLException thrown on failure
     */
	public int getScale(int column) throws SQLException	{
		DataTypeDescriptor dtd = getColumnTypeDescriptor(column);
		// REMIND -- check it is valid to ask for scale
		return dtd.getScale();
	}

    /**
     * What's a column's table name?
     *
     * @return table name or "" if not applicable
	 * @exception SQLException thrown on failure
     */
	public String getTableName(int column) throws SQLException {
		ResultColumnDescriptor cd = columnInfo[column - 1];
		String s = cd.getSourceTableName();

		// database returns null when no table name to differentiate from empty name
		return (s==null? "" : s);
	}

    /**
     * What's a column's table's catalog name?
     *
     * @param column the first column is 1, the second is 2, ...
     * @return column name or "" if not applicable.
	 * @exception SQLException thrown on failure
     */
	public String getCatalogName(int column) throws SQLException {
		validColumnNumber(column);
		return "";
	}

    /**
     * What's a column's SQL type?
     *
     * @param column the first column is 1, the second is 2, ...
     * @return SQL type
     * @see Types
	 * @exception SQLException thrown on failure
     */
	public int getColumnType(int column) throws SQLException {
		DataTypeDescriptor dtd = getColumnTypeDescriptor(column);
		return dtd.getTypeId().getJDBCTypeId();
	}

    /**
     * What's a column's data source specific type name?
     *
     * @param column the first column is 1, the second is 2, ...
     * @return type name
	 * @exception SQLException thrown on failure
     */
	public String getColumnTypeName(int column) throws SQLException	{
		DataTypeDescriptor dtd = getColumnTypeDescriptor(column);
		return dtd.getTypeId().getSQLTypeName();
	}

    /**
     * Is a column definitely not writable?
     *
     * @param column the first column is 1, the second is 2, ...
     * @return true if so
	 * @exception SQLException thrown on failure
     */
	public boolean isReadOnly(int column) throws SQLException {
		validColumnNumber(column);

		// we just don't know if it is a base table column or not
		return false;
	}

    /**
     * Is it possible for a write on the column to succeed?
     *
     * @param column the first column is 1, the second is 2, ...
     * @return true if so
	 * @exception SQLException thrown on failure
     */
	public boolean isWritable(int column) throws SQLException {
		validColumnNumber(column);
		return columnInfo[column - 1].updatableByCursor();
	}

    /**
     * Will a write on the column definitely succeed?
     *
     * @param column the first column is 1, the second is 2, ...
     * @return true if so
	 * @exception SQLException thrown on failure
     */
	public boolean isDefinitelyWritable(int column) throws SQLException	{
		validColumnNumber(column);

		// we just don't know if it is a base table column or not
		return false;
	}

	/*
	 * class interface
	 */

	private void validColumnNumber(int column) throws SQLException {
	  if (column < 1 ||
		        column > getColumnCount() )
			    throw Util.generateCsSQLException(
                      SQLState.COLUMN_NOT_FOUND, new Integer(column));
	}

	public DataTypeDescriptor getColumnTypeDescriptor(int column) throws SQLException 
	{
		validColumnNumber(column);

		ResultColumnDescriptor cd = columnInfo[column - 1];

		return cd.getType();
	}

	/////////////////////////////////////////////////////////////////////////
	//
	//	JDBC 2.0	-	New public methods
	//
	/////////////////////////////////////////////////////////////////////////

    /**
     * JDBC 2.0
     *
     * <p>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.
	 *
	 * @exception SQLException Feature not inplemented for now.
     */
    public String getColumnClassName(int column) throws SQLException {
		
		return getColumnTypeDescriptor(column).getTypeId().getResultSetMetaDataTypeName();
	}


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

		return new org.apache.derby.impl.sql.GenericColumnDescriptor(
			name, DataTypeDescriptor.getBuiltInDataTypeDescriptor(jdcbTypeId, nullable));
	}
	public static ResultColumnDescriptor getResultColumnDescriptor(String name, int jdcbTypeId, boolean nullable, int length) {

		return new org.apache.derby.impl.sql.GenericColumnDescriptor(
			name, DataTypeDescriptor.getBuiltInDataTypeDescriptor(jdcbTypeId, nullable, length));
	}
	public static ResultColumnDescriptor getResultColumnDescriptor(String name, DataTypeDescriptor dtd) {
		return new org.apache.derby.impl.sql.GenericColumnDescriptor(name, dtd);
	}
}