01: /*
02: * Licensed to the Apache Software Foundation (ASF) under one
03: * or more contributor license agreements. See the NOTICE file
04: * distributed with this work for additional information
05: * regarding copyright ownership. The ASF licenses this file
06: * to you under the Apache License, Version 2.0 (the
07: * "License"); you may not use this file except in compliance
08: * with the License. You may obtain a copy of the License at
09: *
10: * http://www.apache.org/licenses/LICENSE-2.0
11: *
12: * Unless required by applicable law or agreed to in writing,
13: * software distributed under the License is distributed on an
14: * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15: * KIND, either express or implied. See the License for the
16: * specific language governing permissions and limitations
17: * under the License.
18: */
19: package org.apache.openjpa.jdbc.sql;
20:
21: /**
22: * SQL UNION.
23: *
24: * @author Abe White
25: */
26: public interface Union extends SelectExecutor {
27:
28: /**
29: * Return the selects that make up this union.
30: */
31: public Select[] getSelects();
32:
33: /**
34: * Get the union-level ordering, if any.
35: */
36: public String getOrdering();
37:
38: /**
39: * Whether this is a true UNION, rather than a logical combination of
40: * independent selects.
41: */
42: public boolean isUnion();
43:
44: /**
45: * Force the use of a series of standard selects rather than a true UNION.
46: */
47: public void abortUnion();
48:
49: /**
50: * Select data using the given selector.
51: */
52: public void select(Selector selector);
53:
54: /**
55: * A callback used to create the selects in a SQL union.
56: */
57: public static interface Selector {
58:
59: /**
60: * Populate the <code>i</code>th select in the union.
61: */
62: public void select(Select sel, int i);
63: }
64: }
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