column.java

来自「一个用java写的开源的数据库系统」· Java 代码 · 共 1,491 行 · 第 1/4 页

            case Types.BIGINT :
                return "BIGINT";

            case Types.REAL :
                return "REAL";

            case Types.FLOAT :
                return "FLOAT";

            case Types.NUMERIC :
                return "NUMERIC";

            case Types.TIMESTAMP :
                return "TIMESTAMP";

            case Types.BINARY :
                return "BINARY";

            case Types.VARBINARY :
                return "VARBINARY";

            case Types.LONGVARBINARY :
                return "LONGVARBINARY";

            case Types.OTHER :
                return "OBJECT";

            default :
                throw Trace.error(Trace.WRONG_DATA_TYPE, type);
        }
    }

    /**
     *  Add two object of a given type
     *
     * @param  a
     * @param  b
     * @param  type
     * @return result
     * @throws  SQLException
     */
    static Object add(Object a, Object b, int type) throws SQLException {

        if (a == null || b == null) {
            return null;
        }

        switch (type) {

            case Types.NULL :
                return null;

            case Types.REAL :
            case Types.FLOAT :
            case Types.DOUBLE :
                double ad = ((Number) a).doubleValue();
                double bd = ((Number) b).doubleValue();

                return new Double(ad + bd);

            case Types.VARCHAR :
            case Types.CHAR :
            case Types.LONGVARCHAR :
            case VARCHAR_IGNORECASE :
                return (String) a + (String) b;

            case Types.NUMERIC :
            case Types.DECIMAL :
                BigDecimal abd = (BigDecimal) a;
                BigDecimal bbd = (BigDecimal) b;

                return abd.add(bbd);

            case Types.TINYINT :
            case Types.SMALLINT :
            case Types.INTEGER :
                int ai = ((Number) a).intValue();
                int bi = ((Number) b).intValue();

                return new Integer(ai + bi);

            case Types.BIGINT :
                long longa = ((Number) a).longValue();
                long longb = ((Number) b).longValue();

                return new Long(longa + longb);

            default :
                throw Trace.error(Trace.FUNCTION_NOT_SUPPORTED, type);
        }
    }

    /**
     *  Concat two objects by turning them into strings first.
     *
     * @param  a
     * @param  b
     * @return result
     * @throws  SQLException
     */
    static Object concat(Object a, Object b) throws SQLException {

        if (a == null) {
            return b;
        } else if (b == null) {
            return a;
        }

        return convertObject(a) + convertObject(b);
    }

    /**
     *  Negate a numeric object.
     *
     * @param  a
     * @param  type
     * @return result
     * @throws  SQLException
     */
    static Object negate(Object a, int type) throws SQLException {

        if (a == null) {
            return null;
        }

        switch (type) {

            case Types.NULL :
                return null;

            case Types.REAL :
            case Types.FLOAT :
            case Types.DOUBLE :
                return new Double(-((Number) a).doubleValue());

            case Types.NUMERIC :
            case Types.DECIMAL :
                return ((BigDecimal) a).negate();

            case Types.TINYINT :
            case Types.SMALLINT :
            case Types.INTEGER :
                return new Integer(-((Number) a).intValue());

            case Types.BIGINT :
                return new Long(-((Number) a).longValue());

            default :
                throw Trace.error(Trace.FUNCTION_NOT_SUPPORTED, type);
        }
    }

    /**
     *  Multiply two numeric objects.
     *
     * @param  a
     * @param  b
     * @param  type
     * @return result
     * @throws  SQLException
     */
    static Object multiply(Object a, Object b, int type) throws SQLException {

        if (a == null || b == null) {
            return null;
        }

        switch (type) {

            case Types.NULL :
                return null;

            case Types.REAL :
            case Types.FLOAT :
            case Types.DOUBLE :
                double ad = ((Number) a).doubleValue();
                double bd = ((Number) b).doubleValue();

                return new Double(ad * bd);

            case Types.NUMERIC :
            case Types.DECIMAL :
                BigDecimal abd = (BigDecimal) a;
                BigDecimal bbd = (BigDecimal) b;

                return abd.multiply(bbd);

            case Types.TINYINT :
            case Types.SMALLINT :
            case Types.INTEGER :
                int ai = ((Number) a).intValue();
                int bi = ((Number) b).intValue();

                return new Integer(ai * bi);

            case Types.BIGINT :
                long longa = ((Number) a).longValue();
                long longb = ((Number) b).longValue();

                return new Long(longa * longb);

            default :
                throw Trace.error(Trace.FUNCTION_NOT_SUPPORTED, type);
        }
    }

    /**
     *  Divide numeric object a by object b.
     *
     * @param  a
     * @param  b
     * @param  type
     * @return result
     * @throws  SQLException
     */
    static Object divide(Object a, Object b, int type) throws SQLException {

        if (a == null || b == null) {
            return null;
        }

        switch (type) {

            case Types.NULL :
                return null;

            case Types.REAL :
            case Types.FLOAT :
            case Types.DOUBLE :
                double ad = ((Number) a).doubleValue();
                double bd = ((Number) b).doubleValue();

                return new Double(ad / bd);

            case Types.NUMERIC :
            case Types.DECIMAL :
                BigDecimal abd   = (BigDecimal) a;
                BigDecimal bbd   = (BigDecimal) b;
                int        scale = abd.scale() > bbd.scale() ? abd.scale()
                                                             : bbd.scale();

                return (bbd.signum() == 0) ? null
                                           : abd.divide(bbd, scale,
                                           BigDecimal.ROUND_HALF_DOWN);

            case Types.TINYINT :
            case Types.SMALLINT :
            case Types.INTEGER :
                int ai = ((Number) a).intValue();
                int bi = ((Number) b).intValue();

                Trace.check(bi != 0, Trace.DIVISION_BY_ZERO);

                return new Integer(ai / bi);

            case Types.BIGINT :
                long longa = ((Number) a).longValue();
                long longb = ((Number) b).longValue();

                return (longb == 0) ? null
                                    : new Long(longa / longb);

            default :
                throw Trace.error(Trace.FUNCTION_NOT_SUPPORTED, type);
        }
    }

    /**
     *  Subtract numeric object b from object a.
     *
     * @param  a
     * @param  b
     * @param  type
     * @return result
     * @throws  SQLException
     */
    static Object subtract(Object a, Object b, int type) throws SQLException {

        if (a == null || b == null) {
            return null;
        }

        switch (type) {

            case Types.NULL :
                return null;

            case Types.REAL :
            case Types.FLOAT :
            case Types.DOUBLE :
                double ad = ((Number) a).doubleValue();
                double bd = ((Number) b).doubleValue();

                return new Double(ad - bd);

            case Types.NUMERIC :
            case Types.DECIMAL :
                BigDecimal abd = (BigDecimal) a;
                BigDecimal bbd = (BigDecimal) b;

                return abd.subtract(bbd);

            case Types.TINYINT :
            case Types.SMALLINT :
            case Types.INTEGER :
                int ai = ((Number) a).intValue();
                int bi = ((Number) b).intValue();

                return new Integer(ai - bi);

            case Types.BIGINT :
                long longa = ((Number) a).longValue();
                long longb = ((Number) b).longValue();

                return new Long(longa - longb);

            default :
                throw Trace.error(Trace.FUNCTION_NOT_SUPPORTED, type);
        }
    }

    /**
     *  Add two numeric objects.
     *
     * @param  a
     * @param  b
     * @param  type
     * @return result
     * @throws  SQLException
     */
    static Object sum(Object a, Object b, int type) throws SQLException {

        if (a == null) {
            return b;
        }

        if (b == null) {
            return a;
        }

        switch (type) {

            case Types.NULL :
                return null;

            case Types.REAL :
            case Types.FLOAT :
            case Types.DOUBLE :
                return new Double(((Number) a).doubleValue()
                                  + ((Number) b).doubleValue());

            case Types.NUMERIC :
            case Types.DECIMAL :
                return ((BigDecimal) a).add((BigDecimal) b);

            case Types.TINYINT :
            case Types.SMALLINT :
            case Types.INTEGER :
                return new Integer(((Number) a).intValue()
                                   + ((Number) b).intValue());

            case Types.BIGINT :
                return new Long(((Number) a).longValue()
                                + ((Number) b).longValue());

            default :
                throw Trace.error(Trace.SUM_OF_NON_NUMERIC);
        }
    }

    /**
     *  Divide numeric object a by int count. Adding all of these values in
     *  a column of the result of a SELECT statement gives the average for