/*
 * @(#)ResultSetMetaData.java	1.20 00/02/02
 *
 * Copyright 1996-2000 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * This software is the proprietary information of Sun Microsystems, Inc.  
 * Use is subject to license terms.
 * 
 */

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>
 */

public interface ResultSetMetaData {

    /**
     * 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, thus read-only.
     *
     * @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.
     *
     * @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 number of decimal digits.
     *
     * @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.
     *
     * @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 column name 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.
	 *
	 * @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
	 * @see <a href="package-summary.html#2.0 API">What Is in the JDBC
	 *      2.0 API</a>
     */
    String getColumnClassName(int column) throws SQLException;
}