org.h2.table.IndexColumn Maven / Gradle / Ivy
/*
* Copyright 2004-2014 H2 Group. Multiple-Licensed under the MPL 2.0,
* and the EPL 1.0 (http://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.table;
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 {
/**
* The column name.
*/
public String columnName;
/**
* The column, or null if not set.
*/
public Column column;
/**
* The sort type. Ascending (the default) and descending are supported;
* nulls can be sorted first or last.
*/
public int sortType = SortOrder.ASCENDING;
/**
* Get the SQL snippet for this index column.
*
* @return the SQL snippet
*/
public String getSQL() {
StringBuilder buff = new StringBuilder(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();
}
/**
* Create an array of index columns from a list of columns. The default sort
* type is used.
*
* @param columns the column list
* @return the index column array
*/
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;
}
/**
* Map the columns using the column names and the specified table.
*
* @param indexColumns the column list with column names set
* @param table the table from where to map the column names to columns
*/
public static void mapColumns(IndexColumn[] indexColumns, Table table) {
for (IndexColumn col : indexColumns) {
col.column = table.getColumn(col.columnName);
}
}
@Override
public String toString() {
return "IndexColumn " + getSQL();
}
}