Source Code Cross Referenced for AggregatedField.java in  » Database-ORM » MMBase » org » mmbase » storage » search » Java Source Code / Java DocumentationJava Source Code and Java Documentation

01:        /*
02:
03:        This software is OSI Certified Open Source Software.
04:        OSI Certified is a certification mark of the Open Source Initiative.
05:
06:        The license (Mozilla version 1.0) can be read at the MMBase site.
07:        See http://www.MMBase.org/license
08:
09:         */
10:        package org.mmbase.storage.search;
11:
12:        /**
13:         * A field in an aggregated query.
14:         * <p>
15:         * Each field in a aggregated query has an aggregation type, which is one of
16:         * the values listed below.
17:         * </ul>
18:         * This corresponds to an aggregated field in SQL SELECT-syntax.
19:         *
20:         * @author Rob van Maris
21:         * @version $Id: AggregatedField.java,v 1.4 2005/04/25 14:56:57 pierre Exp $
22:         * @since MMBase-1.7
23:         */
24:        public interface AggregatedField extends StepField {
25:
26:            /**
27:             * Aggregation type, resulting in grouping the results on non-null
28:             * values of this field.
29:             */
30:            public final static int AGGREGATION_TYPE_GROUP_BY = 1;
31:
32:            /**
33:             * Aggregation type, resulting in count of non-null
34:             * values in this field.
35:             */
36:            public final static int AGGREGATION_TYPE_COUNT = 2;
37:
38:            /**
39:             * Aggregation type, resulting in count of distinct non-null
40:             * values in this field.
41:             */
42:            public final static int AGGREGATION_TYPE_COUNT_DISTINCT = 3;
43:
44:            /** Aggregation type, resulting in minimum value in this field. */
45:            public final static int AGGREGATION_TYPE_MIN = 4;
46:
47:            /** Aggregation type, resulting in maximum value in this field. */
48:            public final static int AGGREGATION_TYPE_MAX = 5;
49:
50:            /**
51:             * Search type descriptions corresponding to the search type values:
52:             * {@link #AGGREGATION_TYPE_GROUP_BY}, {@link #AGGREGATION_TYPE_COUNT}, {@link #AGGREGATION_TYPE_COUNT_DISTINCT},
53:             * {@link #AGGREGATION_TYPE_MIN}, and {@link #AGGREGATION_TYPE_MAX}
54:             */
55:            String[] AGGREGATION_TYPE_DESCRIPTIONS = new String[] { null, // not specified
56:                    "group by", "count", "count distinct", "min", "max" };
57:
58:            /**
59:             * Gets the aggregation type.
60:             */
61:            public int getAggregationType();
62:
63:            /**
64:             * Compares this aggregated field to the specified object. The result is
65:             * <code>true</code> if and only if the argument is a non-null
66:             * <code>AggregatedField</code> object associated with the same field,
67:             * using the same alias, and having the same aggregation type.
68:             *
69:             * @param obj The object to compare with.
70:             * @return <code>true</code> if the objects are equal,
71:             * <code>false</code> otherwise.
72:             */
73:            public boolean equals(Object obj);
74:
75:            /**
76:             * Returns a string representation of this AggregatedField.
77:             * The string representation has the form
78:             * "AggregatedField(step:&lt;step&gt;, fieldname:&lt;fieldname&gt;,
79:             *  alias:&lt;alias&gt;, aggregationtype:&lt;aggregationtype&gt;)"
80:             * where
81:             * <ul>
82:             * <li><em>&lt;step&gt;</em> is the step alias returned by
83:             *     <code>getStep().getAlias()</code> or,
84:             *     when the step alias is <code>null</code>, the step tablename
85:             *     returned by <code>getStep().getTableName()</code>.
86:             * <li><em>&lt;fieldname&gt;</em> is the fieldname returned by
87:             *     {@link #getFieldName getFieldName()}
88:             * <li><em>&lt;alias&gt;</em> is the alias returned by
89:             *     {@link #getAlias getAlias()}
90:             * <li><em>&lt;aggregationtype&gt;</em> is the alias returned by
91:             *     {@link #getAggregationType getAggregationType()}
92:             * </ul>
93:             *
94:             * @return A string representation of this AggregatedField.
95:             */
96:            public String toString();
97:        }