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 }