ResultSetMetaData.java

/* ResultSetMetaData.java -- Returns information about the ResultSet
   Copyright (C) 1999, 2000, 2002, 2006 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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General Public License for more details.

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02110-1301 USA.

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making a combined work based on this library.  Thus, the terms and
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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terms of your choice, provided that you also meet, for each linked
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package java.sql;

/**
 * This interface provides a mechanism for obtaining information about
 * the columns that are present in a <code>ResultSet</code>.
 * 
 * <p> Note that in this class column indices start at 1, not 0.</p>
 *
 * @author Aaron M. Renn (arenn@urbanophile.com)
 */
public interface ResultSetMetaData 
{
  /**
   * The column does not allow NULL's.
   */
  int columnNoNulls = 0;

  /**
   * The column allows NULL's.
   */
  int columnNullable = 1;

  /**
   * It is unknown whether or not the column allows NULL's.
   */
  int columnNullableUnknown = 2;

  /**
   * This method returns the number of columns in the result set.
   *
   * @return The number of columns in the result set.
   * @exception SQLException If an error occurs.
   */
  int getColumnCount() throws SQLException;

  /**
   * This method test whether or not the column is an auto-increment column.
   * Auto-increment columns are read-only.
   *
   * @param columnIndex The index of the column to test.
   * @return <code>true</code> if the column is auto-increment, <code>false</code>
   *         otherwise.
   * @exception SQLException If an error occurs.
   */
  boolean isAutoIncrement(int columnIndex) throws SQLException;

  /**
   * This method tests whether or not a column is case sensitive in its values.
   *
   * @param columnIndex The index of the column to test.
   * @return <code>true</code> if the column value is case sensitive,
   *         <code>false</code> otherwise.
   * @exception SQLException If an error occurs.
   */
  boolean isCaseSensitive(int columnIndex) throws SQLException;

  /**
   * This method tests whether not the specified column can be used in 
   * a WHERE clause.
   *
   * @param columnIndex The index of the column to test.
   * @return <code>true</code> if the column may be used in a WHERE clause,
   *         <code>false</code> otherwise.
   * @exception SQLException If an error occurs.
   */
  boolean isSearchable(int columnIndex) throws SQLException;

  /**
   * This method tests whether or not the column stores a monetary value.
   *
   * @param columnIndex The index of the column to test.
   * @return <code>true</code> if the column contains a monetary value,
   *         <code>false</code> otherwise.
   * @exception SQLException If an error occurs.
   */
  boolean isCurrency(int columnIndex) throws SQLException;

  /**
   * This method returns a value indicating whether or not the specified
   * column may contain a NULL value.
   *
   * @param columnIndex The index of the column to test.
   * @return A constant indicating whether or not the column can contain NULL,
   *         which will be one of <code>columnNoNulls</code>,
   *         <code>columnNullable</code>, or <code>columnNullableUnknown</code>.
   * @exception SQLException If an error occurs.
   */
  int isNullable(int columnIndex) throws SQLException;

  /**
   * This method tests whether or not the value of the specified column
   * is signed or unsigned.
   *
   * @param columnIndex The index of the column to test.
   * @return <code>true</code> if the column value is signed, <code>false</code>
   *         otherwise.
   * @exception SQLException If an error occurs.
   */
  boolean isSigned(int columnIndex) throws SQLException;

  /**
   * This method returns the maximum number of characters that can be used
   * to display a value in this column.
   *
   * @param columnIndex The index of the column to check.
   * @return The maximum number of characters that can be used to display a
   *         value for this column.
   * @exception SQLException If an error occurs.
   */
  int getColumnDisplaySize(int columnIndex) throws SQLException;

  /**
   * This method returns a string that should be used as a caption for this
   * column for user display purposes.
   *
   * @param columnIndex The index of the column to check.
   * @return A display string for the column.
   * @exception SQLException If an error occurs.
   */
  String getColumnLabel(int columnIndex) throws SQLException;

  /**
   * This method returns the name of the specified column.
   *
   * @param columnIndex The index of the column to return the name of.
   * @return The name of the column.
   * @exception SQLException If an error occurs.
   */
  String getColumnName(int columnIndex) throws SQLException;

  /**
   * This method returns the name of the schema that contains the specified
   * column.
   *
   * @param columnIndex The index of the column to check the schema name for.
   * @return The name of the schema that contains the column.
   * @exception SQLException If an error occurs.
   */
  String getSchemaName(int columnIndex) throws SQLException;

  /**
   * This method returns the precision of the specified column, which is the
   * number of decimal digits it contains.
   *
   * @param columnIndex The index of the column to check the precision on.
   * @return The precision of the specified column.
   * @exception SQLException If an error occurs.
   */
  int getPrecision(int columnIndex) throws SQLException;

  /**
   * This method returns the scale of the specified column, which is the
   * number of digits to the right of the decimal point.
   *
   * @param columnIndex The index column to check the scale of.
   * @return The scale of the column.
   * @exception SQLException If an error occurs.
   */
  int getScale(int columnIndex) throws SQLException;

  /**
   * This method returns the name of the table containing the specified
   * column.
   *
   * @param columnIndex The index of the column to check the table name for.
   * @return The name of the table containing the column.
   * @exception SQLException If an error occurs.
   */
  String getTableName(int columnIndex) throws SQLException;

  /**
   * This method returns the name of the catalog containing the specified
   * column.
   *
   * @param columnIndex The index of the column to check the catalog name for.
   * @return The name of the catalog containing the column.
   * @exception SQLException If an error occurs.
   */
  String getCatalogName(int columnIndex) throws SQLException;

  /**
   * This method returns the SQL type of the specified column.  This will
   * be one of the constants from <code>Types</code>.
   *
   * @param columnIndex The index of the column to check the SQL type of.
   * @return The SQL type for this column.
   * @exception SQLException If an error occurs.
   * @see Types
   */
  int getColumnType(int columnIndex) throws SQLException;

  /**
   * This method returns the name of the SQL type for this column.
   *
   * @param columnIndex The index of the column to check the SQL type name for.
   * @return The name of the SQL type for this column.
   * @exception SQLException If an error occurs.
   */
  String getColumnTypeName(int columnIndex) throws SQLException;

  /**
   * This method tests whether or not the specified column is read only.
   *
   * @param columnIndex The index of the column to check.
   * @return <code>true</code> if the column is read only, <code>false</code>
   *         otherwise.
   * @exception SQLException If an error occurs.
   */
  boolean isReadOnly(int columnIndex) throws SQLException;

  /**
   * This method tests whether or not the column may be writable.  This
   * does not guarantee that a write will be successful.
   *
   * @param columnIndex The index of the column to check for writability.
   * @return <code>true</code> if the column may be writable,
   *         <code>false</code> otherwise.
   * @exception SQLException If an error occurs.
   */
  boolean isWritable(int columnIndex) throws SQLException;

  /**
   * This method tests whether or not the column is writable.  This
   * does guarantee that a write will be successful.
   *
   * @param columnIndex The index of the column to check for writability.
   * @return <code>true</code> if the column is writable,
   *         <code>false</code> otherwise.
   * @exception SQLException If an error occurs.
   */
  boolean isDefinitelyWritable(int columnIndex) throws SQLException;

  /**
   * This method returns the name of the Java class which will be used to
   * create objects representing the data in this column.
   *
   * @param columnIndex The index of the column to check.
   * @return The name of the Java class that will be used for values in
   *         this column.
   * @exception SQLException If an error occurs.
   */
  String getColumnClassName(int columnIndex) throws SQLException;
}