resultsetmetadata.java

mysql的jdbc驱动

			return field.isUnsigned() ? "DOUBLE UNSIGNED" : "DOUBLE";

		case MysqlDefs.FIELD_TYPE_NULL:
			return "NULL"; //$NON-NLS-1$

		case MysqlDefs.FIELD_TYPE_TIMESTAMP:
			return "TIMESTAMP"; //$NON-NLS-1$       

		case MysqlDefs.FIELD_TYPE_LONGLONG:
			return field.isUnsigned() ? "BIGINT UNSIGNED" : "BIGINT";

		case MysqlDefs.FIELD_TYPE_INT24:
			return field.isUnsigned() ? "MEDIUMINT UNSIGNED" : "MEDIUMINT";

		case MysqlDefs.FIELD_TYPE_DATE:
			return "DATE"; //$NON-NLS-1$       

		case MysqlDefs.FIELD_TYPE_TIME:
			return "TIME"; //$NON-NLS-1$       

		case MysqlDefs.FIELD_TYPE_DATETIME:
			return "DATETIME"; //$NON-NLS-1$      

		case MysqlDefs.FIELD_TYPE_TINY_BLOB:
			return "TINYBLOB"; //$NON-NLS-1$

		case MysqlDefs.FIELD_TYPE_MEDIUM_BLOB:
			return "MEDIUMBLOB"; //$NON-NLS-1$

		case MysqlDefs.FIELD_TYPE_LONG_BLOB:
			return "LONGBLOB"; //$NON-NLS-1$

		case MysqlDefs.FIELD_TYPE_BLOB:
			if (getField(column).isBinary()) {
				return "BLOB";//$NON-NLS-1$
			}

			return "TEXT";//$NON-NLS-1$

		case MysqlDefs.FIELD_TYPE_VARCHAR:
			return "VARCHAR"; //$NON-NLS-1$

		case MysqlDefs.FIELD_TYPE_VAR_STRING:
			return "VARCHAR"; //$NON-NLS-1$

		case MysqlDefs.FIELD_TYPE_STRING:
			return "CHAR"; //$NON-NLS-1$

		case MysqlDefs.FIELD_TYPE_ENUM:
			return "ENUM"; //$NON-NLS-1$

		case MysqlDefs.FIELD_TYPE_YEAR:
			return "YEAR"; // $NON_NLS-1$

		case MysqlDefs.FIELD_TYPE_SET:
			return "SET"; //$NON-NLS-1$

		default:
			return "UNKNOWN"; //$NON-NLS-1$
		}
	}

	/**
	 * Returns the field instance for the given column index
	 * 
	 * @param columnIndex
	 *            the column number to retrieve a field instance for
	 * 
	 * @return the field instance for the given column index
	 * 
	 * @throws SQLException
	 *             if an error occurs
	 */
	protected Field getField(int columnIndex) throws SQLException {
		if ((columnIndex < 1) || (columnIndex > this.fields.length)) {
			throw new SQLException(Messages.getString("ResultSetMetaData.46"), //$NON-NLS-1$
					SQLError.SQL_STATE_INVALID_COLUMN_NUMBER);
		}

		return this.fields[columnIndex - 1];
	}

	/**
	 * What is a column's number of decimal digits.
	 * 
	 * @param column
	 *            the first column is 1, the second is 2...
	 * 
	 * @return the precision
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public int getPrecision(int column) throws SQLException {
		Field f = getField(column);

		// if (f.getMysqlType() == MysqlDefs.FIELD_TYPE_NEW_DECIMAL) {
		// return f.getLength();
		// }

		if (isDecimalType(f.getSQLType())) {
			if (f.getDecimals() > 0) {
				return clampedGetLength(f) - 1 + f.getPrecisionAdjustFactor();
			}

			return clampedGetLength(f) + f.getPrecisionAdjustFactor();
		}

		switch (f.getMysqlType()) {
		case MysqlDefs.FIELD_TYPE_TINY_BLOB:
		case MysqlDefs.FIELD_TYPE_BLOB:
		case MysqlDefs.FIELD_TYPE_MEDIUM_BLOB:
		case MysqlDefs.FIELD_TYPE_LONG_BLOB:
			return clampedGetLength(f); // this may change in the future
		// for now, the server only
		// returns FIELD_TYPE_BLOB for _all_
		// BLOB types, but varying lengths
		// indicating the _maximum_ size
		// for each BLOB type.
		default:
			return clampedGetLength(f) / f.getMaxBytesPerCharacter();

		}
	}

	/**
	 * What is a column's number of digits to the right of the decimal point?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2...
	 * 
	 * @return the scale
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public int getScale(int column) throws SQLException {
		Field f = getField(column);

		if (isDecimalType(f.getSQLType())) {
			return f.getDecimals();
		}

		return 0;
	}

	/**
	 * What is a column's table's schema? This relies on us knowing the table
	 * name. The JDBC specification allows us to return "" if this is not
	 * applicable.
	 * 
	 * @param column
	 *            the first column is 1, the second is 2...
	 * 
	 * @return the Schema
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public String getSchemaName(int column) throws SQLException {
		return ""; //$NON-NLS-1$
	}

	/**
	 * Whats a column's table's name?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2...
	 * 
	 * @return column name, or "" if not applicable
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public String getTableName(int column) throws SQLException {
		return getField(column).getTableName();
	}

	/**
	 * Is the column automatically numbered (and thus read-only)
	 * 
	 * @param column
	 *            the first column is 1, the second is 2...
	 * 
	 * @return true if so
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public boolean isAutoIncrement(int column) throws SQLException {
		Field f = getField(column);

		return f.isAutoIncrement();
	}

	/**
	 * Does a column's case matter?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2...
	 * 
	 * @return true if so
	 * 
	 * @throws java.sql.SQLException
	 *             if a database access error occurs
	 */
	public boolean isCaseSensitive(int column) throws java.sql.SQLException {
		Field field = getField(column);

		int sqlType = field.getSQLType();

		switch (sqlType) {
		case Types.BIT:
		case Types.TINYINT:
		case Types.SMALLINT:
		case Types.INTEGER:
		case Types.BIGINT:
		case Types.FLOAT:
		case Types.REAL:
		case Types.DOUBLE:
		case Types.DATE:
		case Types.TIME:
		case Types.TIMESTAMP:
			return false;

		case Types.CHAR:
		case Types.VARCHAR:
		case Types.LONGVARCHAR:

			if (field.isBinary()) {
				return true;
			}

			String collationName = field.getCollation();

			return ((collationName != null) && !collationName.endsWith("_ci"));

		default:
			return true;
		}
	}

	/**
	 * Is the column a cash value?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2...
	 * 
	 * @return true if its a cash column
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public boolean isCurrency(int column) throws SQLException {
		return false;
	}

	/**
	 * Will a write on this column definately succeed?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2, etc..
	 * 
	 * @return true if so
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public boolean isDefinitelyWritable(int column) throws SQLException {
		return isWritable(column);
	}

	/**
	 * Can you put a NULL in this column?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2...
	 * 
	 * @return one of the columnNullable values
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public int isNullable(int column) throws SQLException {
		if (!getField(column).isNotNull()) {
			return java.sql.ResultSetMetaData.columnNullable;
		}

		return java.sql.ResultSetMetaData.columnNoNulls;
	}

	/**
	 * Is the column definitely not writable?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2, etc.
	 * 
	 * @return true if so
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public boolean isReadOnly(int column) throws SQLException {
		return getField(column).isReadOnly();
	}

	/**
	 * Can the column be used in a WHERE clause? Basically for this, I split the
	 * functions into two types: recognised types (which are always useable),
	 * and OTHER types (which may or may not be useable). The OTHER types, for
	 * now, I will assume they are useable. We should really query the catalog
	 * to see if they are useable.
	 * 
	 * @param column
	 *            the first column is 1, the second is 2...
	 * 
	 * @return true if they can be used in a WHERE clause
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public boolean isSearchable(int column) throws SQLException {
		return true;
	}

	/**
	 * Is the column a signed number?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2...
	 * 
	 * @return true if so
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public boolean isSigned(int column) throws SQLException {
		Field f = getField(column);
		int sqlType = f.getSQLType();

		switch (sqlType) {
		case Types.TINYINT:
		case Types.SMALLINT:
		case Types.INTEGER:
		case Types.BIGINT:
		case Types.FLOAT:
		case Types.REAL:
		case Types.DOUBLE:
		case Types.NUMERIC:
		case Types.DECIMAL:
			return !f.isUnsigned();

		case Types.DATE:
		case Types.TIME:
		case Types.TIMESTAMP:
			return false;

		default:
			return false;
		}
	}

	// *********************************************************************
	//
	// END OF PUBLIC INTERFACE
	//
	// *********************************************************************

	/**
	 * Is it possible for a write on the column to succeed?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2, etc.
	 * 
	 * @return true if so
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public boolean isWritable(int column) throws SQLException {
		return !isReadOnly(column);
	}

	/**
	 * Returns a string representation of this object
	 * 
	 * @return ...
	 */
	public String toString() {
		StringBuffer toStringBuf = new StringBuffer();
		toStringBuf.append(super.toString());
		toStringBuf.append(" - Field level information: "); //$NON-NLS-1$

		for (int i = 0; i < this.fields.length; i++) {
			toStringBuf.append("\n\t"); //$NON-NLS-1$
			toStringBuf.append(this.fields[i].toString());
		}

		return toStringBuf.toString();
	}
}