tinysqlresultsetmetadata.java

TinySQL是一个轻量级的纯java数据库引擎

/*
 * tinySQLResultSetMetaData
 *
 * This is the tinySQL Result Set Meta Data class.
 *
 * A lot of this code is based on or directly taken from
 * George Reese's ([e-mail]) mSQL driver.
 *
 * So, it's probably safe to say:
 *
 * Portions of this code Copyright (c) 1996 George Reese
 *
 * The rest of it:
 *
 * Copyright 1996, Brian C. Jepson
 *                 ([e-mail])
 * $Author: davis $
 * $Date: 2004/12/18 21:32:53 $
 * $Revision: 1.1 $
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 *
 */

package com.sqlmagic.tinysql;

import java.sql.SQLException;
import java.sql.Types;

public class tinySQLResultSetMetaData implements java.sql.ResultSetMetaData {

  /**
   *
   * The result set.
   *
   */
  private tsResultSet tsql;

  /**
   *
   * Constructs a tinySQLResultSet; requires a tsResultSet object
   * @param result the tsResultSet object
   *
   */
  public tinySQLResultSetMetaData(tsResultSet result) {
    tsql = result;
  }

  /**
   *
   * Returns the number of columns in this result set.
   * @see java.sqlResultSetMetaData#getColumnCount
   * @return number of columns
   *
   */
  public int getColumnCount() throws SQLException {
    return tsql.getColumnCount();
  }

  /**
   *
   * Is the column an autoincrement (identity, counter) column?
   * @see java.sql.ResultSetMetaData#isAutoIncrement
   * @return false - tinySQL does not support autoincrement columns
   *
   */
  public boolean isAutoIncrement(int column) throws SQLException { 
    return false;
  }

  /**
   *
   * Is case significant in column names?
   * @see java.sql.ResultSetMetaData#isCaseSensitive
   * @return true
   *
   */
  public boolean isCaseSensitive(int column) throws SQLException {
    return true;
  }

  /**
   *
   * Can the column be used in a where clause?
   * @see java.sql.ResultSetMetaData#isSearchable
   * @return 
   *
   */
  public boolean isSearchable(int column) throws SQLException {
    return true;
  }

  /**
   *
   * Is the column some sort of currency?
   * @see java.sql.ResultSetMetaData#isCurrency
   * @return tinySQL doesn't have such things, so it's false
   *
   */
  public boolean isCurrency(int column) throws SQLException {
    return false;
  }

  /**
   *
   * Determines if the column in question is nullable. tinySQL
   * does not yet support nulls.
   * @see java.sql.ResultSetMetaData#isNullable
   * @return columnNoNulls, columnNullable, or columnNullableUnknown
   *
   */
  public int isNullable(int column) throws SQLException{
    return columnNoNulls;
  }

  /**
   *
   * All tinySQL integers are signed, so this returns true.
   * @see java.sql.ResultSetMetaData#isSigned
   * @return true
   *
   */
  public boolean isSigned(int column) throws SQLException {
    return true;
  }

  /**
   *
   * Gives the display size for this column.
   * @see java.sql.ResultSetMetaData#getColumnDisplaySize
   *
   */
  public int getColumnDisplaySize(int column) throws SQLException {

    // get a column object. Remember, tinySQL uses a column
    // offset of zero, but JDBC columns start numbering at one.
    // That's why there's a -1 in the columnAtIndex invocation.
    //
    tsColumn col = tsql.columnAtIndex(column-1);
    return col.size;

  }

  /**
   *
   * This returns the column name in the form table_name.column_name.
   * @see java.sql.ResultSetMetaData#getColumnLabel
   * @param column the column whose label is wanted
   * @return the fully qualified column name
   *
   */
  public String getColumnLabel(int column)
       throws SQLException {

    // get the column, return its table and name, separated by a '.'
    //
    tsColumn col = tsql.columnAtIndex(column-1);
    return (col.tableName + "." + col.name);
  }

  /**
   * The name of a given column
   * @see java.sql.ResultSetMetaData#getColumnName
   * @param column the column whose name is wanted
   * @return the name of the requested column
   */
  public String getColumnName(int column)
       throws SQLException {

    // get the column and return its name
    //
    String columnName;
    int dotAt;
    String msg;
    tsColumn col = tsql.columnAtIndex(column-1);
    dotAt = col.name.indexOf(".");
    columnName = col.name;
    if ( dotAt > -1 ) columnName = col.name.substring(dotAt + 1);
    if ( col.alias != (String)null )
       if ( !col.alias.equals(columnName) ) return col.alias;
    columnName = tinySQLGlobals.getLongName(columnName);
    return columnName;
  }

  /**
   *
   * What's the column's schema? This is not applicable to tinySQL,
   * so it returns an empty string.
   *
   */
  public String getSchemaName(int column)
       throws SQLException {
    return "";
  }

  /**
   * 
   * What's the column's precision? Use size.
   *
   */
  public int getPrecision(int column)
       throws SQLException {
    tsColumn col = tsql.columnAtIndex(column-1);
    return col.size;
  }

  /**
   *
   * What's a column's number of digits to right of decimal?
   *
   */
  public int getScale(int column) throws SQLException {
    tsColumn col = tsql.columnAtIndex(column-1);
    return col.decimalPlaces;
  }

  /**
   *
   * Gives the name of the table to which this column belongs.
   * @see java.sql.ResultSetMetaData#getTableName
   * @param column the column of the field this information is needed for
   * @return the table name
   *
   */
  public String getTableName(int column)
       throws SQLException {

    // retrieve the column info and return the table name
    //
    tsColumn col = tsql.columnAtIndex(column-1);
    return col.tableName;
  }

  /**
   * 
   * Return the column's table catalog name. Not supported by tinySQL
   * 
   */
  public String getCatalogName(int column)
       throws SQLException {
    throw new SQLException("tinySQL does not support catalogues.");
  }

  /**
   *
   * Gives the column type using the types in java.sql.Types.
   * @see java.sqlTypes
   * @see java.sql.ResultSetMetaData#getColumnType
   * @exception SQLException thrown for any number of reasons
   * @param column the column type information is needed on
   * @return the type as listed in java.sql.Types
   *
   */
  public int getColumnType(int column) throws SQLException {

    // get the column info object
    //
    tsColumn col = tsql.columnAtIndex(column-1);
    return col.type;
  }

  /**
   *
   * Gives the column type as a string.
   * @see java.sql.ResultSetMetaData#getColumnTypeName
   * @exception SQLException thrown at you
   * @param column the column for which the type name is wanted
   * @return the name of the column type
   *
   * @author Thomas Morgner <[e-mail]>: This function does 
   * not properly return type names - everything except INTEGER or
   * CHAR returns &quot;NULL&quot;
   */
  public String getColumnTypeName(int column)
       throws SQLException {

    // just call getColumnType, and report on what it said
    //
    switch(getColumnType(column)) {

    case Types.INTEGER:
      return "INT";

    case Types.CHAR:
      return "CHAR";

    case Types.FLOAT:
      return "FLOAT";

    case Types.DATE:
      return "DATE";
    default:
      return "NULL";
    }
  }

  /**
   *
   * Is the column definitely not writable? This has no meaning
   * in tinySQL
   *
   */
  public boolean isReadOnly(int column) throws SQLException {
    return false;
  }

  /**
   *
   * Is the column potentially writable? This has no meaning
   * in tinySQL
   *
   */
  public boolean isWritable(int column) throws SQLException {
    return true;
  }

  /**
   *
   * Is the column definitely writable? This has no meaning
   * in tinySQL
   *
   */
  public boolean isDefinitelyWritable(int column) throws SQLException {
    return true;
  }

    //--------------------------JDBC 2.0-----------------------------------

    /**
     * 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
     */
    public String getColumnClassName(int column) throws SQLException {
      throw new SQLException("tinySQL does not support getColumnClassName.");
    }
}