Java tutorial
/* * Copyright (c) 1996, 2005, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.sql; /** * An object that can be used to get information about the types * and properties of the columns in a <code>ResultSet</code> object. * The following code fragment creates the <code>ResultSet</code> object rs, * creates the <code>ResultSetMetaData</code> object rsmd, and uses rsmd * to find out how many columns rs has and whether the first column in rs * can be used in a <code>WHERE</code> clause. * <PRE> * * ResultSet rs = stmt.executeQuery("SELECT a, b, c FROM TABLE2"); * ResultSetMetaData rsmd = rs.getMetaData(); * int numberOfColumns = rsmd.getColumnCount(); * boolean b = rsmd.isSearchable(1); * * </PRE> * * @since 1.1 */ public interface ResultSetMetaData extends Wrapper { /** * Returns the number of columns in this <code>ResultSet</code> object. * * @return the number of columns * @exception SQLException if a database access error occurs */ int getColumnCount() throws SQLException; /** * Indicates whether the designated column is automatically numbered. * * @param column the first column is 1, the second is 2, ... * @return <code>true</code> if so; <code>false</code> otherwise * @exception SQLException if a database access error occurs */ boolean isAutoIncrement(int column) throws SQLException; /** * Indicates whether a column's case matters. * * @param column the first column is 1, the second is 2, ... * @return <code>true</code> if so; <code>false</code> otherwise * @exception SQLException if a database access error occurs */ boolean isCaseSensitive(int column) throws SQLException; /** * Indicates whether the designated column can be used in a where clause. * * @param column the first column is 1, the second is 2, ... * @return <code>true</code> if so; <code>false</code> otherwise * @exception SQLException if a database access error occurs */ boolean isSearchable(int column) throws SQLException; /** * Indicates whether the designated column is a cash value. * * @param column the first column is 1, the second is 2, ... * @return <code>true</code> if so; <code>false</code> otherwise * @exception SQLException if a database access error occurs */ boolean isCurrency(int column) throws SQLException; /** * Indicates the nullability of values in the designated column. * * @param column the first column is 1, the second is 2, ... * @return the nullability status of the given column; one of <code>columnNoNulls</code>, * <code>columnNullable</code> or <code>columnNullableUnknown</code> * @exception SQLException if a database access error occurs */ int isNullable(int column) throws SQLException; /** * The constant indicating that a * column does not allow <code>NULL</code> values. */ int columnNoNulls = 0; /** * The constant indicating that a * column allows <code>NULL</code> values. */ int columnNullable = 1; /** * The constant indicating that the * nullability of a column's values is unknown. */ int columnNullableUnknown = 2; /** * Indicates whether values in the designated column are signed numbers. * * @param column the first column is 1, the second is 2, ... * @return <code>true</code> if so; <code>false</code> otherwise * @exception SQLException if a database access error occurs */ boolean isSigned(int column) throws SQLException; /** * Indicates the designated column's normal maximum width in characters. * * @param column the first column is 1, the second is 2, ... * @return the normal maximum number of characters allowed as the width * of the designated column * @exception SQLException if a database access error occurs */ int getColumnDisplaySize(int column) throws SQLException; /** * Gets the designated column's suggested title for use in printouts and * displays. The suggested title is usually specified by the SQL <code>AS</code> * clause. If a SQL <code>AS</code> is not specified, the value returned from * <code>getColumnLabel</code> will be the same as the value returned by the * <code>getColumnName</code> method. * * @param column the first column is 1, the second is 2, ... * @return the suggested column title * @exception SQLException if a database access error occurs */ String getColumnLabel(int column) throws SQLException; /** * Get the designated column's name. * * @param column the first column is 1, the second is 2, ... * @return column name * @exception SQLException if a database access error occurs */ String getColumnName(int column) throws SQLException; /** * Get the designated 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 if a database access error occurs */ String getSchemaName(int column) throws SQLException; /** * Get the designated column's specified column size. * For numeric data, this is the maximum precision. For character data, this is the length in characters. * For datetime datatypes, this is the length in characters of the String representation (assuming the * maximum allowed precision of the fractional seconds component). For binary data, this is the length in bytes. For the ROWID datatype, * this is the length in bytes. 0 is returned for data types where the * column size is not applicable. * * @param column the first column is 1, the second is 2, ... * @return precision * @exception SQLException if a database access error occurs */ int getPrecision(int column) throws SQLException; /** * Gets the designated column's number of digits to right of the decimal point. * 0 is returned for data types where the scale is not applicable. * * @param column the first column is 1, the second is 2, ... * @return scale * @exception SQLException if a database access error occurs */ int getScale(int column) throws SQLException; /** * Gets the designated column's table name. * * @param column the first column is 1, the second is 2, ... * @return table name or "" if not applicable * @exception SQLException if a database access error occurs */ String getTableName(int column) throws SQLException; /** * Gets the designated column's table's catalog name. * * @param column the first column is 1, the second is 2, ... * @return the name of the catalog for the table in which the given column * appears or "" if not applicable * @exception SQLException if a database access error occurs */ String getCatalogName(int column) throws SQLException; /** * Retrieves the designated column's SQL type. * * @param column the first column is 1, the second is 2, ... * @return SQL type from java.sql.Types * @exception SQLException if a database access error occurs * @see Types */ int getColumnType(int column) throws SQLException; /** * Retrieves the designated column's database-specific type name. * * @param column the first column is 1, the second is 2, ... * @return type name used by the database. If the column type is * a user-defined type, then a fully-qualified type name is returned. * @exception SQLException if a database access error occurs */ String getColumnTypeName(int column) throws SQLException; /** * Indicates whether the designated column is definitely not writable. * * @param column the first column is 1, the second is 2, ... * @return <code>true</code> if so; <code>false</code> otherwise * @exception SQLException if a database access error occurs */ boolean isReadOnly(int column) throws SQLException; /** * Indicates whether it is possible for a write on the designated column to succeed. * * @param column the first column is 1, the second is 2, ... * @return <code>true</code> if so; <code>false</code> otherwise * @exception SQLException if a database access error occurs */ boolean isWritable(int column) throws SQLException; /** * Indicates whether a write on the designated column will definitely succeed. * * @param column the first column is 1, the second is 2, ... * @return <code>true</code> if so; <code>false</code> otherwise * @exception SQLException if a database access error occurs */ boolean isDefinitelyWritable(int column) throws SQLException; //--------------------------JDBC 2.0----------------------------------- /** * <p>Returns the fully-qualified name of the Java class whose instances * are manufactured if the method <code>ResultSet.getObject</code> * is called to retrieve a value * from the column. <code>ResultSet.getObject</code> may return a subclass of the * class returned by this method. * * @param column the first column is 1, the second is 2, ... * @return the fully-qualified name of the class in the Java programming * language that would be used by the method * <code>ResultSet.getObject</code> to retrieve the value in the specified * column. This is the class name used for custom mapping. * @exception SQLException if a database access error occurs * @since 1.2 */ String getColumnClassName(int column) throws SQLException; }