001    /* ResultSetMetaData.java -- Returns information about the ResultSet
002       Copyright (C) 1999, 2000, 2002, 2006 Free Software Foundation, Inc.
003    
004    This file is part of GNU Classpath.
005    
006    GNU Classpath is free software; you can redistribute it and/or modify
007    it under the terms of the GNU General Public License as published by
008    the Free Software Foundation; either version 2, or (at your option)
009    any later version.
010    
011    GNU Classpath is distributed in the hope that it will be useful, but
012    WITHOUT ANY WARRANTY; without even the implied warranty of
013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014    General Public License for more details.
015    
016    You should have received a copy of the GNU General Public License
017    along with GNU Classpath; see the file COPYING.  If not, write to the
018    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019    02110-1301 USA.
020    
021    Linking this library statically or dynamically with other modules is
022    making a combined work based on this library.  Thus, the terms and
023    conditions of the GNU General Public License cover the whole
024    combination.
025    
026    As a special exception, the copyright holders of this library give you
027    permission to link this library with independent modules to produce an
028    executable, regardless of the license terms of these independent
029    modules, and to copy and distribute the resulting executable under
030    terms of your choice, provided that you also meet, for each linked
031    independent module, the terms and conditions of the license of that
032    module.  An independent module is a module which is not derived from
033    or based on this library.  If you modify this library, you may extend
034    this exception to your version of the library, but you are not
035    obligated to do so.  If you do not wish to do so, delete this
036    exception statement from your version. */
037    
038    
039    package 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     */
049    public 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    }