001: /**********************************************************************
002: Copyright (c) 2008 Andy Jefferson and others. All rights reserved.
003: Licensed under the Apache License, Version 2.0 (the "License");
004: you may not use this file except in compliance with the License.
005: You may obtain a copy of the License at
006:
007: http://www.apache.org/licenses/LICENSE-2.0
008:
009: Unless required by applicable law or agreed to in writing, software
010: distributed under the License is distributed on an "AS IS" BASIS,
011: WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012: See the License for the specific language governing permissions and
013: limitations under the License.
014:
015: Contributors:
016: ...
017: **********************************************************************/package org.jpox.store.expression;
018:
019: import org.jpox.exceptions.JPOXUserException;
020:
021: /**
022: * An expression representing a subquery.
023: *
024: * @version $Revision: 1.6 $
025: **/
026: public class SubqueryExpression extends BooleanExpression {
027: /** Subquery expression. */
028: private final QueryExpression subqueryExpr;
029:
030: /**
031: * Construct an expression containing this subquery.
032: * @param qs the QueryExpression
033: * @param expr Expression for the subquery
034: */
035: public SubqueryExpression(QueryExpression qs, QueryExpression expr) {
036: super (qs);
037:
038: this .subqueryExpr = expr;
039:
040: // Mark the subquery as having our statement as its parent
041: expr.setParent(qs);
042:
043: st.append("(").append(expr).append(')');
044: }
045:
046: /**
047: * Convenience accessor for the subquery expression.
048: * @return Subquery expression
049: */
050: public QueryExpression getSubquery() {
051: return subqueryExpr;
052: }
053:
054: /**
055: * Method to convert the subquery statement into ALL ({subquery})
056: */
057: public void all() {
058: // TODO This is RDBMS-specific and shouldn't be in here
059: st.clearStatement();
060: st.append("ALL (").append(subqueryExpr).append(")");
061: }
062:
063: /**
064: * Method to convert the subquery statement into ANY ({subquery})
065: */
066: public void any() {
067: // TODO This is RDBMS-specific and shouldn't be in here
068: st.clearStatement();
069: st.append("ANY (").append(subqueryExpr).append(")");
070: }
071:
072: /**
073: * Method to convert the subquery statement into EXISTS ({subquery})
074: */
075: public void exists() {
076: // TODO This is RDBMS-specific and shouldn't be in here
077: st.clearStatement();
078: st.append("EXISTS (").append(subqueryExpr).append(")");
079: }
080:
081: /**
082: * Method to convert the subquery statement into "expr IN ({subquery})"
083: * @param expr The expression that is being contained
084: * @return BooleanExpression for the IN
085: */
086: public BooleanExpression in(ScalarExpression expr) {
087: return new InExpression(expr, OP_IN, this );
088: }
089:
090: /**
091: * Method to return an expression for whether the specified expression is contained in this subquery.
092: * Uses IN operator.
093: * @param expr The expression that is being contained
094: * @return BooleanExpression for the contains(expr)
095: */
096: public BooleanExpression containsMethod(ScalarExpression expr) {
097: return in(expr);
098: }
099:
100: /**
101: * Method to return the size of the subquery.
102: * @return Size of the subquery
103: */
104: public NumericExpression sizeMethod() {
105: throw new JPOXUserException(
106: "size() is not currently supported on subqueries. Use COUNT(*) in the subquery");
107: }
108:
109: /**
110: * Method to return an expression for whether the subquery is empty (no results).
111: * @return BooleanExpression for the isEmpty()
112: */
113: public BooleanExpression isEmptyMethod() {
114: throw new JPOXUserException(
115: "isEmpty() is not currently supported on subqueries. Use COUNT(*) in the subquery and compare with 0");
116: }
117: }
|