select.java

纯Java的数据库

/* Copyright (c) 1995-2000, The Hypersonic SQL Group.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of the Hypersonic SQL Group nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE HYPERSONIC SQL GROUP,
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * This software consists of voluntary contributions made by many individuals
 * on behalf of the Hypersonic SQL Group.
 *
 *
 * For work added by the HSQL Development Group:
 *
 * Copyright (c) 2001-2008, The HSQL Development Group
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of the HSQL Development Group nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL HSQL DEVELOPMENT GROUP, HSQLDB.ORG,
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */


package org.hsqldb;

import org.hsqldb.HsqlNameManager.HsqlName;
import org.hsqldb.lib.HashMap;
import org.hsqldb.lib.HashSet;
import org.hsqldb.lib.HsqlArrayList;
import org.hsqldb.lib.IntKeyHashMap;
import org.hsqldb.lib.Iterator;

// fredt@users 20010701 - patch 1.6.1 by hybris
// basic implementation of LIMIT n m
// fredt@users 20020130 - patch 471710 by fredt - LIMIT rewritten
// for SELECT LIMIT n m DISTINCT
// fredt@users 20020221 - patch 513005 by sqlbob@users (RMP)
// type and logging attributes of sIntotable
// fredt@users 20020230 - patch 495938 by johnhobs@users - GROUP BY order
// fred@users 20020522 - patch 1.7.0 - aggregate functions with DISTINCT
// rougier@users 20020522 - patch 552830 - COUNT(DISTINCT)
// fredt@users 20020804 - patch 580347 by dkkopp - view speedup
// tony_lai@users 20021020 - patch 1.7.2 - improved aggregates and HAVING
// boucherb@users 20030811 - patch 1.7.2 - prepared statement support
// fredt@users 20031012 - patch 1.7.2 - better OUTER JOIN implementation
// fredt@users 20031012 - patch 1.7.2 - SQL standard ORDER BY with UNION and other set queries
// fredt@users 200408xx - patch 1.7.2 - correct evaluation of the precedence of nested UNION and other set query

/**
 * The compiled representation of an SQL SELECT.
 *
 * Extended in successive versions of HSQLDB.
 *
 * @author Thomas Mueller (Hypersonic SQL Group)
 * @version 1.8.0
 * @since Hypersonic SQL
 */
class Select {

    boolean               isDistinctSelect;
    boolean               isAggregated;
    private boolean       isGrouped;
    private HashSet       groupColumnNames;
    TableFilter[]         tFilter;
    Expression            limitCondition;
    Expression            queryCondition;     // null means no condition
    Expression            havingCondition;    // null means none
    Expression[]          exprColumns;        // 'result', 'group' and 'order' columns
    int                   iResultLen;         // number of columns that are 'result'
    int                   iGroupLen;          // number of columns that are 'group'
    int                   iHavingLen;         // number of columns that are 'group'
    int                   iOrderLen;          // number of columns that are 'order'
    int[]                 sortOrder;
    int[]                 sortDirection;
    boolean               sortUnion;          // if true, sort the result of the full union
    HsqlName              sIntoTable;         // null means not select..into
    int                   intoType;
    Select[]              unionArray;         // only set in the first Select in a union chain
    int                   unionMaxDepth;      // max unionDepth in chain
    Select                unionSelect;        // null means no union select
    int                   unionType;
    int                   unionDepth;
    static final int      NOUNION   = 0,
                          UNION     = 1,
                          UNIONALL  = 2,
                          INTERSECT = 3,
                          EXCEPT    = 4;
    private boolean       simpleLimit;        // true if maxrows can be uses as is
    Result.ResultMetaData resultMetaData;
    IntKeyHashMap         asteriskPositions;

    /**
     * Experimental.
     *
     * Map the column aliases to expressions in order to resolve alias names
     * in WHERE clauses
     *
     */
    HashMap getColumnAliases() {

        HashMap aliasMap = new HashMap();

        for (int i = 0; i < iResultLen; i++) {
            String alias = exprColumns[i].getAlias();

            if (alias != null) {
                aliasMap.put(alias, exprColumns[i]);
            }
        }

        return aliasMap;
    }

    /**
     * Method declaration
     *
     *
     * @throws HsqlException
     */
    void resolve(Session session) throws HsqlException {

        resolveTables();
        resolveTypes(session);
        setFilterConditions(session);
    }

    /**
     * Method declaration
     *
     *
     * @throws HsqlException
     */
    private void resolveTables() throws HsqlException {

        // replace the aliases with expressions
        for (int i = iResultLen; i < exprColumns.length; i++) {
            if (exprColumns[i].getType() == Expression.COLUMN) {
                if (exprColumns[i].joinedTableColumnIndex == -1) {
                    boolean descending = exprColumns[i].isDescending();

                    exprColumns[i] =
                        exprColumns[i].getExpressionForAlias(exprColumns,
                            iResultLen);

                    if (descending) {
                        exprColumns[i].setDescending();
                    }
                }
            } else {
                exprColumns[i].replaceAliases(exprColumns, iResultLen);
            }
        }

        if (queryCondition != null) {
            queryCondition.replaceAliases(exprColumns, iResultLen);
        }

        int len = tFilter.length;

        for (int i = 0; i < len; i++) {
            resolveTables(tFilter[i]);
        }
    }

    /**
     * Converts the types of the columns in set operations to those in the first
     * Select.
     */
    void resolveUnionColumnTypes() throws HsqlException {

        if (unionSelect != null) {
            if (unionSelect.iResultLen != iResultLen) {
                throw Trace.error(Trace.COLUMN_COUNT_DOES_NOT_MATCH);
            }

            for (int i = 0; i < iResultLen; i++) {
                Expression e = exprColumns[i];

                if (!e.isTypeEqual(unionSelect.exprColumns[i])) {
                    unionSelect.exprColumns[i] =
                        new Expression(unionSelect.exprColumns[i],
                                       e.getDataType(), e.getColumnSize(),
                                       e.getColumnScale());
                }
            }
        }
    }

    /**
     * Sets the types of all the expressions that have so far resolved.
     *
     * @throws HsqlException
     */
    void resolveTypes(Session session) throws HsqlException {

        int len = exprColumns.length;

        for (int i = 0; i < len; i++) {
            exprColumns[i].resolveTypes(session);
        }

        if (queryCondition != null) {
            queryCondition.resolveTypes(session);
        }
    }

    void resolveTablesUnion(TableFilter f) throws HsqlException {

        if (unionArray == null) {
            resolveTables(f);
        } else {
            for (int i = 0; i < unionArray.length; i++) {
                unionArray[i].resolveTables(f);
            }
        }
    }

    /**
     * Resolves the tables for all the Expression in the Select object
     * if it is possible to do so with the given TableFilter.
     *
     * @param f
     *
     * @throws HsqlException
     */
    void resolveTables(TableFilter f) throws HsqlException {

        int len = exprColumns.length;

        for (int i = 0; i < len; i++) {
            exprColumns[i].resolveTables(f);
        }

        if (queryCondition != null) {
            queryCondition.resolveTables(f);
        }
    }

    private void setFilterConditions(Session session) throws HsqlException {

        if (queryCondition == null) {
            return;
        }

        for (int i = 0; i < tFilter.length; i++) {
            tFilter[i].setConditions(session, queryCondition);
        }
    }

    /**
     * Check all Expression have resolved. Return true or false as a result.
     * Throw if false and check parameter is true.
     *
     * @throws HsqlException
     */
    boolean checkResolved(boolean check) throws HsqlException {

        boolean result = true;
        int     len    = exprColumns.length;

        for (int i = 0; i < len; i++) {
            result = result && exprColumns[i].checkResolved(check);
        }

        if (queryCondition != null) {
            result = result && queryCondition.checkResolved(check);
        }

        if (havingCondition != null) {
            result = result && havingCondition.checkResolved(check);
        }

        for (int i = 0; i < tFilter.length; i++) {
            if (tFilter[i].filterIndex == null) {
                tFilter[i].filterIndex =
                    tFilter[i].filterTable.getPrimaryIndex();
            }
        }

        return result;
    }

    /**
     * Removes all the TableFilters from the Expressions.
     *
     * @throws HsqlException
     */
/*
    void removeFilters() throws HsqlException {

        int len = eColumn.length;

        for (int i = 0; i < len; i++) {
            eColumn[i].removeFilters();
        }

        if (eCondition != null) {
            eCondition.removeFilters();
        }
    }
*/

    /**
     * Returns a single value result or throws if the result has more than
     * one row with one value.
     *
     * @param type data type
     * @param session context
     * @return the single valued result
     * @throws HsqlException
     */
    Object getValue(Session session, int type) throws HsqlException {

        resolve(session);

        Result r    = getResult(session, 2);    // 2 records are required for test
        int    size = r.getSize();
        int    len  = r.getColumnCount();

        if (len == 1) {
            if (size == 0) {
                return null;
            } else if (size == 1) {
                Object o = r.rRoot.data[0];

                return r.metaData.colTypes[0] == type ? o
                                                      : Column.convertObject(
                                                      o, type);
            } else {
                throw Trace.error(Trace.CARDINALITY_VIOLATION_NO_SUBCLASS);
            }
        }

        HsqlException e =
            Trace.error(Trace.CARDINALITY_VIOLATION_NO_SUBCLASS);

        throw new HsqlInternalException(e);
    }

    /**
     * Resolves expressions and pepares thre metadata for the result.
     */
    void prepareResult(Session session) throws HsqlException {

        resolveAll(session, true);

        if (iGroupLen > 0) {    // has been set in Parser
            isGrouped        = true;
            groupColumnNames = new HashSet();

            for (int i = iResultLen; i < iResultLen + iGroupLen; i++) {

//              MarcH: this is wrong for a CASE WHEN statement in a SELECT CASE WHEN ...,<something aggregate> statement
//              collectColumnName collects no columns if exprColumns[i]'s expressiontype is Expression.CASEWHEN
//              collectAllColumnNames collects all columns used in the CASE WHEN statement
//              exprColumns[i].collectColumnName(groupColumnNames);
                exprColumns[i].collectAllColumnNames(groupColumnNames);
            }
        }

        int len = exprColumns.length;

        resultMetaData = new Result.ResultMetaData(len);

        Result.ResultMetaData rmd = resultMetaData;

        // tony_lai@users having
        int groupByStart = iResultLen;
        int groupByEnd   = groupByStart + iGroupLen;
        int orderByStart = groupByEnd + iHavingLen;
        int orderByEnd   = orderByStart + iOrderLen;

        for (int i = 0; i < len; i++) {
            Expression e = exprColumns[i];

            rmd.colTypes[i]  = e.getDataType();
            rmd.colSizes[i]  = e.getColumnSize();
            rmd.colScales[i] = e.getColumnScale();

            if (e.isAggregate()) {
                isAggregated = true;
            }