indexcolumn.java

来自「非常棒的java数据库」· Java 代码 · 共 50 行

/*
 * Copyright 2004-2008 H2 Group. Licensed under the H2 License, Version 1.0
 * (http://h2database.com/html/license.html).
 * Initial Developer: H2 Group
 */
package org.h2.table;

import java.sql.SQLException;

import org.h2.result.SortOrder;

/**
 * This represents a column item of an index. This is required because some
 * indexes support descending sorted columns.
 */
public class IndexColumn {
    public String columnName;
    public Column column;
    public int sortType = SortOrder.ASCENDING;

    public String getSQL() {
        StringBuffer buff = new StringBuffer(column.getSQL());
        if ((sortType & SortOrder.DESCENDING) != 0) {
            buff.append(" DESC");
        }
        if ((sortType & SortOrder.NULLS_FIRST) != 0) {
            buff.append(" NULLS FIRST");
        } else if ((sortType & SortOrder.NULLS_LAST) != 0) {
            buff.append(" NULLS LAST");
        }
        return buff.toString();
    }

    public static IndexColumn[] wrap(Column[] columns) {
        IndexColumn[] list = new IndexColumn[columns.length];
        for (int i = 0; i < list.length; i++) {
            list[i] = new IndexColumn();
            list[i].column = columns[i];
        }
        return list;
    }

    public static void mapColumns(IndexColumn[] indexColumns, Table table) throws SQLException {
        for (int i = 0; i < indexColumns.length; i++) {
            IndexColumn col = indexColumns[i];
            col.column = table.getColumn(col.columnName);
        }
    }
}