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1
5 package org.h2.samples;
6
7 import java.sql.Connection  ;
8 import java.sql.DriverManager ;
9 import java.sql.PreparedStatement ;
10 import java.sql.ResultSet ;
11 import java.sql.SQLException ;
12 import java.sql.Statement ;
13 import java.sql.Types ;
14
15 import org.h2.tools.SimpleResultSet;
16
17 public class FunctionMultiReturn {
18
19 public static void main(String [] args) throws Exception {
20 Class.forName("org.h2.Driver");
21 Connection conn = DriverManager.getConnection("jdbc:h2:mem:", "sa", "");
22 Statement stat = conn.createStatement();
23 stat.execute("CREATE ALIAS P2C FOR \"org.h2.samples.FunctionMultiReturn.polar2Cartesian\" ");
24 PreparedStatement prep = conn.prepareStatement("SELECT X, Y FROM P2C(?, ?)");
25 prep.setDouble(1, 5.0);
26 prep.setDouble(2, 0.5);
27 ResultSet rs = prep.executeQuery();
28 while(rs.next()) {
29 double x = rs.getDouble(1);
30 double y = rs.getDouble(2);
31 System.out.println("result: (x=" + x + ", y="+y+")");
32 }
33
34 stat.execute("CREATE TABLE TEST(ID IDENTITY, R DOUBLE, A DOUBLE)");
35 stat.execute("INSERT INTO TEST(R, A) VALUES(5.0, 0.5), (10.0, 0.6)");
36 stat.execute("CREATE ALIAS P2C_SET FOR \"org.h2.samples.FunctionMultiReturn.polar2CartesianSet\" ");
37 rs = conn.createStatement().executeQuery("SELECT * FROM P2C_SET('SELECT * FROM TEST')");
38 while(rs.next()) {
39 double r = rs.getDouble("R");
40 double a = rs.getDouble("A");
41 double x = rs.getDouble("X");
42 double y = rs.getDouble("Y");
43 System.out.println("(r="+r+" a="+a+") : (x=" + x + ", y="+y+")");
44 }
45
46 stat.execute("CREATE ALIAS P2C_A FOR \"org.h2.samples.FunctionMultiReturn.polar2CartesianArray\" ");
47 rs = conn.createStatement().executeQuery("SELECT R, A, P2C_A(R, A) FROM TEST");
48 while(rs.next()) {
49 double r = rs.getDouble(1);
50 double a = rs.getDouble(2);
51 Object o = rs.getObject(3);
52 Object [] xy = (Object []) o;
53 double x = ((Double )xy[0]).doubleValue();
54 double y = ((Double )xy[1]).doubleValue();
55 System.out.println("(r="+r+" a="+a+") : (x=" + x + ", y="+y+")");
56 }
57
58 rs = conn.createStatement().executeQuery("SELECT R, A, ARRAY_GET(E, 1), ARRAY_GET(E, 2) FROM (SELECT R, A, P2C_A(R, A) E FROM TEST)");
59 while(rs.next()) {
60 double r = rs.getDouble(1);
61 double a = rs.getDouble(2);
62 double x = rs.getDouble(3);
63 double y = rs.getDouble(4);
64 System.out.println("(r="+r+" a="+a+") : (x=" + x + ", y="+y+")");
65 }
66
67 conn.close();
68 }
69
70
74 public static ResultSet polar2Cartesian(Double r, Double alpha) throws SQLException {
75 SimpleResultSet rs = new SimpleResultSet();
76 rs.addColumn("X", Types.DOUBLE, 0, 0);
77 rs.addColumn("Y", Types.DOUBLE, 0, 0);
78 if(r != null && alpha != null) {
79 double x = r.doubleValue() * Math.cos(alpha.doubleValue());
80 double y = r.doubleValue() * Math.sin(alpha.doubleValue());
81 rs.addRow(new Object [] { new Double (x), new Double (y) });
82 }
83 return rs;
84 }
85
86
90 public static Object [] polar2CartesianArray(Double r, Double alpha) throws SQLException {
91 double x = r.doubleValue() * Math.cos(alpha.doubleValue());
92 double y = r.doubleValue() * Math.sin(alpha.doubleValue());
93 return new Object []{new Double (x), new Double (y)};
94 }
95
96 public static ResultSet polar2CartesianSet(Connection conn, String query) throws SQLException {
97 SimpleResultSet result = new SimpleResultSet();
98 result.addColumn("R", Types.DOUBLE, 0, 0);
99 result.addColumn("A", Types.DOUBLE, 0, 0);
100 result.addColumn("X", Types.DOUBLE, 0, 0);
101 result.addColumn("Y", Types.DOUBLE, 0, 0);
102 if(query != null) {
103 ResultSet rs = conn.createStatement().executeQuery(query);
104 while(rs.next()) {
105 double r = rs.getDouble("R");
106 double alpha = rs.getDouble("A");
107 double x = r * Math.cos(alpha);
108 double y = r * Math.sin(alpha);
109 result.addRow(new Object [] { new Double (r), new Double (alpha), new Double (x), new Double (y) });
110 }
111 }
112 return result;
113 }
114
115 }
116 |
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