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1
5 package org.h2.expression;
6
7 import java.sql.SQLException  ;
8
9 import org.h2.command.dml.Query;
10 import org.h2.engine.Session;
11 import org.h2.message.Message;
12 import org.h2.result.LocalResult;
13 import org.h2.table.ColumnResolver;
14 import org.h2.table.TableFilter;
15 import org.h2.value.Value;
16 import org.h2.value.ValueArray;
17 import org.h2.value.ValueNull;
18
19
22
23 public class Subquery extends Expression {
24
25 private Query query;
26
27 public Subquery(Query query) {
28 this.query = query;
29 }
30
31 public Value getValue(Session session) throws SQLException {
32 query.setSession(session);
33 LocalResult result = query.query(2);
34 try {
35 int rowcount = result.getRowCount();
36 if(rowcount > 1) {
37 throw Message.getSQLException(Message.SCALAR_SUBQUERY_CONTAINS_MORE_THAN_ONE_ROW);
38 }
39 Value v;
40 if(rowcount <= 0) {
41 v = ValueNull.INSTANCE;
42 } else {
43 result.next();
44 Value[] values = result.currentRow();
45 if(result.getVisibleColumnCount() == 1) {
46 v = values[0];
47 } else {
48 v = ValueArray.get(values);
49 }
50 }
51 return v;
52 } finally {
53 result.close();
54 }
55 }
56
57 public int getType() {
58 return getExpression().getType();
59 }
60
61 public void mapColumns(ColumnResolver resolver, int level) throws SQLException {
62 query.mapColumns(resolver, level + 1);
63 }
64
65 public Expression optimize(Session session) throws SQLException {
66 query.prepare();
67 return this;
68 }
69
70 public void setEvaluatable(TableFilter tableFilter, boolean b) {
71 query.setEvaluatable(tableFilter, b);
72 }
73
74 public int getScale() {
75 return getExpression().getScale();
76 }
77
78 public long getPrecision() {
79 return getExpression().getPrecision();
80 }
81
82 public String getSQL() {
83 return "(" + query.getPlan() +")";
84 }
85
86 public void updateAggregate(Session session) {
87 }
89
90 private Expression getExpression() {
91 return (Expression) query.getExpressions().get(0);
92 }
93
94 public boolean isEverything(ExpressionVisitor visitor) {
95 return query.isEverything(visitor);
96 }
97
98 public Query getQuery() {
99 return query;
100 }
101
102 public int getCost() {
103 return 10 + (int)(10 * query.getCost());
104 }
105
106 }
107 |
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