001/* ResultSetMetaData.java -- Returns information about the ResultSet
002   Copyright (C) 1999, 2000, 2002, 2006 Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038
039package java.sql;
040
041/**
042 * This interface provides a mechanism for obtaining information about
043 * the columns that are present in a <code>ResultSet</code>.
044 *
045 * <p> Note that in this class column indices start at 1, not 0.</p>
046 *
047 * @author Aaron M. Renn (arenn@urbanophile.com)
048 */
049public interface ResultSetMetaData
050{
051  /**
052   * The column does not allow NULL's.
053   */
054  int columnNoNulls = 0;
055
056  /**
057   * The column allows NULL's.
058   */
059  int columnNullable = 1;
060
061  /**
062   * It is unknown whether or not the column allows NULL's.
063   */
064  int columnNullableUnknown = 2;
065
066  /**
067   * This method returns the number of columns in the result set.
068   *
069   * @return The number of columns in the result set.
070   * @exception SQLException If an error occurs.
071   */
072  int getColumnCount() throws SQLException;
073
074  /**
075   * This method test whether or not the column is an auto-increment column.
076   * Auto-increment columns are read-only.
077   *
078   * @param columnIndex The index of the column to test.
079   * @return <code>true</code> if the column is auto-increment, <code>false</code>
080   *         otherwise.
081   * @exception SQLException If an error occurs.
082   */
083  boolean isAutoIncrement(int columnIndex) throws SQLException;
084
085  /**
086   * This method tests whether or not a column is case sensitive in its values.
087   *
088   * @param columnIndex The index of the column to test.
089   * @return <code>true</code> if the column value is case sensitive,
090   *         <code>false</code> otherwise.
091   * @exception SQLException If an error occurs.
092   */
093  boolean isCaseSensitive(int columnIndex) throws SQLException;
094
095  /**
096   * This method tests whether not the specified column can be used in
097   * a WHERE clause.
098   *
099   * @param columnIndex The index of the column to test.
100   * @return <code>true</code> if the column may be used in a WHERE clause,
101   *         <code>false</code> otherwise.
102   * @exception SQLException If an error occurs.
103   */
104  boolean isSearchable(int columnIndex) throws SQLException;
105
106  /**
107   * This method tests whether or not the column stores a monetary value.
108   *
109   * @param columnIndex The index of the column to test.
110   * @return <code>true</code> if the column contains a monetary value,
111   *         <code>false</code> otherwise.
112   * @exception SQLException If an error occurs.
113   */
114  boolean isCurrency(int columnIndex) throws SQLException;
115
116  /**
117   * This method returns a value indicating whether or not the specified
118   * column may contain a NULL value.
119   *
120   * @param columnIndex The index of the column to test.
121   * @return A constant indicating whether or not the column can contain NULL,
122   *         which will be one of <code>columnNoNulls</code>,
123   *         <code>columnNullable</code>, or <code>columnNullableUnknown</code>.
124   * @exception SQLException If an error occurs.
125   */
126  int isNullable(int columnIndex) throws SQLException;
127
128  /**
129   * This method tests whether or not the value of the specified column
130   * is signed or unsigned.
131   *
132   * @param columnIndex The index of the column to test.
133   * @return <code>true</code> if the column value is signed, <code>false</code>
134   *         otherwise.
135   * @exception SQLException If an error occurs.
136   */
137  boolean isSigned(int columnIndex) throws SQLException;
138
139  /**
140   * This method returns the maximum number of characters that can be used
141   * to display a value in this column.
142   *
143   * @param columnIndex The index of the column to check.
144   * @return The maximum number of characters that can be used to display a
145   *         value for this column.
146   * @exception SQLException If an error occurs.
147   */
148  int getColumnDisplaySize(int columnIndex) throws SQLException;
149
150  /**
151   * This method returns a string that should be used as a caption for this
152   * column for user display purposes.
153   *
154   * @param columnIndex The index of the column to check.
155   * @return A display string for the column.
156   * @exception SQLException If an error occurs.
157   */
158  String getColumnLabel(int columnIndex) throws SQLException;
159
160  /**
161   * This method returns the name of the specified column.
162   *
163   * @param columnIndex The index of the column to return the name of.
164   * @return The name of the column.
165   * @exception SQLException If an error occurs.
166   */
167  String getColumnName(int columnIndex) throws SQLException;
168
169  /**
170   * This method returns the name of the schema that contains the specified
171   * column.
172   *
173   * @param columnIndex The index of the column to check the schema name for.
174   * @return The name of the schema that contains the column.
175   * @exception SQLException If an error occurs.
176   */
177  String getSchemaName(int columnIndex) throws SQLException;
178
179  /**
180   * This method returns the precision of the specified column, which is the
181   * number of decimal digits it contains.
182   *
183   * @param columnIndex The index of the column to check the precision on.
184   * @return The precision of the specified column.
185   * @exception SQLException If an error occurs.
186   */
187  int getPrecision(int columnIndex) throws SQLException;
188
189  /**
190   * This method returns the scale of the specified column, which is the
191   * number of digits to the right of the decimal point.
192   *
193   * @param columnIndex The index column to check the scale of.
194   * @return The scale of the column.
195   * @exception SQLException If an error occurs.
196   */
197  int getScale(int columnIndex) throws SQLException;
198
199  /**
200   * This method returns the name of the table containing the specified
201   * column.
202   *
203   * @param columnIndex The index of the column to check the table name for.
204   * @return The name of the table containing the column.
205   * @exception SQLException If an error occurs.
206   */
207  String getTableName(int columnIndex) throws SQLException;
208
209  /**
210   * This method returns the name of the catalog containing the specified
211   * column.
212   *
213   * @param columnIndex The index of the column to check the catalog name for.
214   * @return The name of the catalog containing the column.
215   * @exception SQLException If an error occurs.
216   */
217  String getCatalogName(int columnIndex) throws SQLException;
218
219  /**
220   * This method returns the SQL type of the specified column.  This will
221   * be one of the constants from <code>Types</code>.
222   *
223   * @param columnIndex The index of the column to check the SQL type of.
224   * @return The SQL type for this column.
225   * @exception SQLException If an error occurs.
226   * @see Types
227   */
228  int getColumnType(int columnIndex) throws SQLException;
229
230  /**
231   * This method returns the name of the SQL type for this column.
232   *
233   * @param columnIndex The index of the column to check the SQL type name for.
234   * @return The name of the SQL type for this column.
235   * @exception SQLException If an error occurs.
236   */
237  String getColumnTypeName(int columnIndex) throws SQLException;
238
239  /**
240   * This method tests whether or not the specified column is read only.
241   *
242   * @param columnIndex The index of the column to check.
243   * @return <code>true</code> if the column is read only, <code>false</code>
244   *         otherwise.
245   * @exception SQLException If an error occurs.
246   */
247  boolean isReadOnly(int columnIndex) throws SQLException;
248
249  /**
250   * This method tests whether or not the column may be writable.  This
251   * does not guarantee that a write will be successful.
252   *
253   * @param columnIndex The index of the column to check for writability.
254   * @return <code>true</code> if the column may be writable,
255   *         <code>false</code> otherwise.
256   * @exception SQLException If an error occurs.
257   */
258  boolean isWritable(int columnIndex) throws SQLException;
259
260  /**
261   * This method tests whether or not the column is writable.  This
262   * does guarantee that a write will be successful.
263   *
264   * @param columnIndex The index of the column to check for writability.
265   * @return <code>true</code> if the column is writable,
266   *         <code>false</code> otherwise.
267   * @exception SQLException If an error occurs.
268   */
269  boolean isDefinitelyWritable(int columnIndex) throws SQLException;
270
271  /**
272   * This method returns the name of the Java class which will be used to
273   * create objects representing the data in this column.
274   *
275   * @param columnIndex The index of the column to check.
276   * @return The name of the Java class that will be used for values in
277   *         this column.
278   * @exception SQLException If an error occurs.
279   */
280  String getColumnClassName(int columnIndex) throws SQLException;
281}