Package org.castor.cpa.persistence.sql.driver

Source Code of org.castor.cpa.persistence.sql.driver.SapDbQueryExpression

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* $Id: SapDbQueryExpression.java 7585 2008-05-03 18:45:19Z rjoachim $
*/
package org.castor.cpa.persistence.sql.driver;

import java.util.Enumeration;
import java.util.Vector;

import org.exolab.castor.jdo.engine.JDBCSyntax;
import org.exolab.castor.persist.spi.PersistenceFactory;

/**
* QueryExpression for SAP DB.
*
* @author <a href="mailto:on@ibis.odessa.ua">Oleg Nitz</a>
* @version $Revision: 7585 $ $Date: 2004-10-01 07:25:46 -0600 (Fri, 01 Oct 2004) $
*/
public final class SapDbQueryExpression extends JDBCQueryExpression {
    public SapDbQueryExpression(final PersistenceFactory factory) {
        super(factory);
    }

    public String getStatement(final boolean lock) {
        Join         join;
        StringBuffer sql;
        boolean      first;
        Enumeration  enumeration;
        int          size;
        Vector       sorted = new Vector();

        sql = new StringBuffer();
        sql.append(JDBCSyntax.SELECT);
        if (_distinct) {
            sql.append(JDBCSyntax.DISTINCT);
        }

        sql.append(getColumnList());

        sql.append(JDBCSyntax.FROM);
        // Add all the tables to the FROM clause
        // They should go in the special order: the table from the left side of outer join
        // should go before the table from the right side.
        // first add elements that participate in outer joins
        enumeration = _joins.elements();
        while (enumeration.hasMoreElements()) {
            int left;
            int right;

            join = (Join) enumeration.nextElement();
            if (!join._outer) {
                continue;
            }
            left = sorted.indexOf(join._leftTable);
            right = sorted.indexOf(join._rightTable);
            if (left >= 0 && right >= 0) {
                if (left > right) {
                    sorted.removeElement(join._leftTable);
                    sorted.insertElementAt(join._leftTable, right);
                }
            } else if (left < 0 && right >= 0) {
                sorted.insertElementAt(join._leftTable, right);
            } else if (left >= 0 && right < 0) {
                sorted.insertElementAt(join._rightTable, left + 1);
            } else { // (left < 0 && right < 0)
                sorted.addElement(join._leftTable);
                sorted.addElement(join._rightTable);
            }
        }
        // now add elements that don't participate in outer joins
        enumeration = _tables.keys();
        while (enumeration.hasMoreElements()) {
            Object name;

            name = enumeration.nextElement();
            if (!sorted.contains(name)) {
                sorted.addElement(name);
            }
        }
        // Append all the tables (from sorted) to the sql string.
        enumeration = sorted.elements();
        while (enumeration.hasMoreElements()) {
            String tableAlias = (String) enumeration.nextElement();
            String tableName = (String) _tables.get(tableAlias);
            if (tableAlias.equals(tableName)) {
                sql.append(_factory.quoteName(tableName));
            } else {
                sql.append(_factory.quoteName(tableName) + " "
                        + _factory.quoteName(tableAlias));
            }
            if (enumeration.hasMoreElements()) {
                sql.append(JDBCSyntax.TABLE_SEPARATOR);
            }
        }
        first = true;
        // Use asterisk notation to denote a left outer join
        // and equals to denote an inner join
        size = _joins.size();
        for (int i = 0; i < size; ++i) {
            if (first) {
                sql.append(JDBCSyntax.WHERE);
                first = false;
            } else {
                sql.append(JDBCSyntax.AND);
            }

            join = (Join) _joins.elementAt(i);
            for (int j = 0; j < join._leftColumns.length; ++j) {
                if (j > 0) {
                    sql.append(JDBCSyntax.AND);
                }

                sql.append(_factory.quoteName(join._leftTable
                        + JDBCSyntax.TABLE_COLUMN_SEPARATOR
                        + join._leftColumns[j]));

                sql.append(OP_EQUALS);
                sql.append(_factory.quoteName(join._rightTable
                        + JDBCSyntax.TABLE_COLUMN_SEPARATOR
                        + join._rightColumns[j]));
                if (join._outer) {
                    sql.append("(+)");
                }
            }
        }
        first = addWhereClause(sql, first);

        if (_order != null) {
            sql.append(JDBCSyntax.ORDER_BY).append(_order);
        }

        // Use WITH LOCK to lock selected tables.
        if (lock) {
            sql.append(" WITH LOCK");
        }
        return sql.toString();
    }
}


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