ResultSetMetaData


1   /*
2    * @(#)ResultSetMetaData.java   1.27 03/12/19
3    *
4    * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
5    * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
6    */
7   
8   package java.sql;
9   
10  /**
11   * An object that can be used to get information about the types 
12   * and properties of the columns in a <code>ResultSet</code> object.
13   * The following code fragment creates the <code>ResultSet</code> object rs,
14   * creates the <code>ResultSetMetaData</code> object rsmd, and uses rsmd
15   * to find out how many columns rs has and whether the first column in rs
16   * can be used in a <code>WHERE</code> clause.
17   * <PRE>
18   *
19   *     ResultSet rs = stmt.executeQuery("SELECT a, b, c FROM TABLE2");
20   *     ResultSetMetaData rsmd = rs.getMetaData();
21   *     int numberOfColumns = rsmd.getColumnCount();
22   *     boolean b = rsmd.isSearchable(1);
23   *
24   * </PRE>
25   */
26  
27  public interface ResultSetMetaData {
28  
29      /**
30       * Returns the number of columns in this <code>ResultSet</code> object.
31       *
32       * @return the number of columns
33       * @exception SQLException if a database access error occurs
34       */
35      int getColumnCount() throws SQLException  ;
36  
37      /**
38       * Indicates whether the designated column is automatically numbered, thus read-only.
39       *
40       * @param column the first column is 1, the second is 2, ...
41       * @return <code>true</code> if so; <code>false</code> otherwise
42       * @exception SQLException if a database access error occurs
43       */
44      boolean isAutoIncrement(int column) throws SQLException  ;
45  
46      /**
47       * Indicates whether a column's case matters.
48       *
49       * @param column the first column is 1, the second is 2, ...
50       * @return <code>true</code> if so; <code>false</code> otherwise
51       * @exception SQLException if a database access error occurs
52       */
53      boolean isCaseSensitive(int column) throws SQLException  ;    
54  
55      /**
56       * Indicates whether the designated column can be used in a where clause.
57       *
58       * @param column the first column is 1, the second is 2, ...
59       * @return <code>true</code> if so; <code>false</code> otherwise
60       * @exception SQLException if a database access error occurs
61       */
62      boolean isSearchable(int column) throws SQLException  ;
63  
64      /**
65       * Indicates whether the designated column is a cash value.
66       *
67       * @param column the first column is 1, the second is 2, ...
68       * @return <code>true</code> if so; <code>false</code> otherwise
69       * @exception SQLException if a database access error occurs
70       */
71      boolean isCurrency(int column) throws SQLException  ;
72  
73      /**
74       * Indicates the nullability of values in the designated column.        
75       *
76       * @param column the first column is 1, the second is 2, ...
77       * @return the nullability status of the given column; one of <code>columnNoNulls</code>,
78       *          <code>columnNullable</code> or <code>columnNullableUnknown</code>
79       * @exception SQLException if a database access error occurs
80       */
81      int isNullable(int column) throws SQLException  ;
82  
83      /**
84       * The constant indicating that a
85       * column does not allow <code>NULL</code> values.
86       */
87      int columnNoNulls = 0;
88  
89      /**
90       * The constant indicating that a
91       * column allows <code>NULL</code> values.
92       */
93      int columnNullable = 1;
94  
95      /**
96       * The constant indicating that the
97       * nullability of a column's values is unknown.
98       */
99      int columnNullableUnknown = 2;
100 
101     /**
102      * Indicates whether values in the designated column are signed numbers.
103      *
104      * @param column the first column is 1, the second is 2, ...
105      * @return <code>true</code> if so; <code>false</code> otherwise
106      * @exception SQLException if a database access error occurs
107      */
108     boolean isSigned(int column) throws SQLException  ;
109 
110     /**
111      * Indicates the designated column's normal maximum width in characters.
112      *
113      * @param column the first column is 1, the second is 2, ...
114      * @return the normal maximum number of characters allowed as the width
115      *          of the designated column
116      * @exception SQLException if a database access error occurs
117      */
118     int getColumnDisplaySize(int column) throws SQLException  ;
119 
120     /**
121      * Gets the designated column's suggested title for use in printouts and
122      * displays.
123      *
124      * @param column the first column is 1, the second is 2, ...
125      * @return the suggested column title
126      * @exception SQLException if a database access error occurs
127      */
128     String   getColumnLabel(int column) throws SQLException  ;  
129 
130     /**
131      * Get the designated column's name.
132      *
133      * @param column the first column is 1, the second is 2, ...
134      * @return column name
135      * @exception SQLException if a database access error occurs
136      */
137     String   getColumnName(int column) throws SQLException  ;
138 
139     /**
140      * Get the designated column's table's schema.
141      *
142      * @param column the first column is 1, the second is 2, ...
143      * @return schema name or "" if not applicable
144      * @exception SQLException if a database access error occurs
145      */
146     String   getSchemaName(int column) throws SQLException  ;
147 
148     /**
149      * Get the designated column's number of decimal digits.
150      *
151      * @param column the first column is 1, the second is 2, ...
152      * @return precision
153      * @exception SQLException if a database access error occurs
154      */
155     int getPrecision(int column) throws SQLException  ;
156 
157     /**
158      * Gets the designated column's number of digits to right of the decimal point.
159      *
160      * @param column the first column is 1, the second is 2, ...
161      * @return scale
162      * @exception SQLException if a database access error occurs
163      */
164     int getScale(int column) throws SQLException  ;   
165 
166     /**
167      * Gets the designated column's table name. 
168      *
169      * @param column the first column is 1, the second is 2, ...
170      * @return table name or "" if not applicable
171      * @exception SQLException if a database access error occurs
172      */
173     String   getTableName(int column) throws SQLException  ;
174 
175     /**
176      * Gets the designated column's table's catalog name.
177      *
178      * @param column the first column is 1, the second is 2, ...
179      * @return the name of the catalog for the table in which the given column
180      *          appears or "" if not applicable
181      * @exception SQLException if a database access error occurs
182      */
183     String   getCatalogName(int column) throws SQLException  ;
184 
185     /**
186      * Retrieves the designated column's SQL type.
187      *
188      * @param column the first column is 1, the second is 2, ...
189      * @return SQL type from java.sql.Types
190      * @exception SQLException if a database access error occurs
191      * @see Types
192      */
193     int getColumnType(int column) throws SQLException  ;
194 
195     /**
196      * Retrieves the designated column's database-specific type name.
197      *
198      * @param column the first column is 1, the second is 2, ...
199      * @return type name used by the database. If the column type is
200      * a user-defined type, then a fully-qualified type name is returned.
201      * @exception SQLException if a database access error occurs
202      */
203     String   getColumnTypeName(int column) throws SQLException  ;
204 
205     /**
206      * Indicates whether the designated column is definitely not writable.
207      *
208      * @param column the first column is 1, the second is 2, ...
209      * @return <code>true</code> if so; <code>false</code> otherwise
210      * @exception SQLException if a database access error occurs
211      */
212     boolean isReadOnly(int column) throws SQLException  ;
213 
214     /**
215      * Indicates whether it is possible for a write on the designated column to succeed.
216      *
217      * @param column the first column is 1, the second is 2, ...
218      * @return <code>true</code> if so; <code>false</code> otherwise
219      * @exception SQLException if a database access error occurs
220      */
221     boolean isWritable(int column) throws SQLException  ;
222 
223     /**
224      * Indicates whether a write on the designated column will definitely succeed.  
225      *
226      * @param column the first column is 1, the second is 2, ...
227      * @return <code>true</code> if so; <code>false</code> otherwise
228      * @exception SQLException if a database access error occurs
229      */
230     boolean isDefinitelyWritable(int column) throws SQLException  ;
231 
232     //--------------------------JDBC 2.0-----------------------------------
233 
234     /**
235      * <p>Returns the fully-qualified name of the Java class whose instances 
236      * are manufactured if the method <code>ResultSet.getObject</code>
237      * is called to retrieve a value 
238      * from the column.  <code>ResultSet.getObject</code> may return a subclass of the
239      * class returned by this method.
240      *
241      * @param column the first column is 1, the second is 2, ...
242      * @return the fully-qualified name of the class in the Java programming
243      *         language that would be used by the method 
244      * <code>ResultSet.getObject</code> to retrieve the value in the specified
245      * column. This is the class name used for custom mapping.
246      * @exception SQLException if a database access error occurs
247      * @since 1.2
248      */
249     String   getColumnClassName(int column) throws SQLException  ;
250 }
251
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