Support "SELECT version()"

Patch from Andrew Gaul argaul@gmail.com
Fixes issue 406.

h2/src/docsrc/help/help.csv

@@ -3811,6 +3811,14 @@ Returns the name of the current user of this session.
 CURRENT_USER()
 "
 
+"Functions (System)","VERSION","
+VERSION()
+","
+Returns the H2 version as a String.
+","
+VERSION()
+"
+
 "System Tables","Information Schema","
 INFORMATION_SCHEMA
 ","

h2/src/docsrc/html/changelog.html

@@ -25,6 +25,7 @@ Change Log
 </li><li>MVStore: old data is now retained for 45 seconds by default.
 </ul><li>MVStore: compress is now disabled by default, and can be enabled on request.
 </ul><li>Support ALTER TABLE ADD ... AFTER. Patch from Andrew Gaul argaul@gmail.com. Fixes issue 401.
+</ul><li>support "SELECT version()". Patch from Andrew Gaul argaul@gmail.com. Fixes issue 406.
 </li></ul>
 
 <h2>Version 1.3.170 (2012-11-30)</h2>

h2/src/main/org/h2/expression/Function.java

@@ -26,6 +26,7 @@ import java.util.regex.PatternSyntaxException;
 import org.h2.command.Command;
 import org.h2.command.Parser;
 import org.h2.constant.ErrorCode;
+import org.h2.engine.Constants;
 import org.h2.engine.Database;
 import org.h2.engine.Mode;
 import org.h2.engine.Session;
@@ -97,7 +98,8 @@ public class Function extends Expression implements FunctionCall {
             CASE = 206, NEXTVAL = 207, CURRVAL = 208, ARRAY_GET = 209, CSVREAD = 210, CSVWRITE = 211,
             MEMORY_FREE = 212, MEMORY_USED = 213, LOCK_MODE = 214, SCHEMA = 215, SESSION_ID = 216, ARRAY_LENGTH = 217,
             LINK_SCHEMA = 218, GREATEST = 219, LEAST = 220, CANCEL_SESSION = 221, SET = 222, TABLE = 223, TABLE_DISTINCT = 224,
-            FILE_READ = 225, TRANSACTION_ID = 226, TRUNCATE_VALUE = 227, NVL2 = 228, DECODE = 229, ARRAY_CONTAINS = 230;
+            FILE_READ = 225, TRANSACTION_ID = 226, TRUNCATE_VALUE = 227, NVL2 = 228, DECODE = 229, ARRAY_CONTAINS = 230,
+            VERSION = 231;
 
     public static final int ROW_NUMBER = 300;
 
@@ -343,6 +345,7 @@ public class Function extends Expression implements FunctionCall {
         addFunction("FILE_READ", FILE_READ, VAR_ARGS, Value.NULL, false, false, false);
         addFunctionNotDeterministic("TRANSACTION_ID", TRANSACTION_ID, 0, Value.STRING);
         addFunctionWithNull("DECODE", DECODE, VAR_ARGS, Value.NULL);
+        addFunction("VERSION", VERSION, 0, Value.STRING);
 
         // TableFunction
         addFunctionWithNull("TABLE", TABLE, VAR_ARGS, Value.RESULT_SET);
@@ -1114,6 +1117,9 @@ public class Function extends Expression implements FunctionCall {
         case LPAD:
             result = ValueString.get(StringUtils.pad(v0.getString(), v1.getInt(), v2 == null ? null : v2.getString(), false));
             break;
+        case VERSION:
+            result = ValueString.get(Constants.getVersion());
+            break;
             // date
         case DATE_ADD:
             result = ValueTimestamp.get(dateadd(v0.getString(), v1.getInt(), v2.getTimestamp()));

h2/src/test/org/h2/test/db/TestFunctions.java

@@ -29,6 +29,7 @@ import java.util.Properties;
 import java.util.UUID;
 import org.h2.api.AggregateFunction;
 import org.h2.constant.ErrorCode;
+import org.h2.engine.Constants;
 import org.h2.store.fs.FileUtils;
 import org.h2.test.TestBase;
 import org.h2.tools.SimpleResultSet;
@@ -54,6 +55,7 @@ public class TestFunctions extends TestBase implements AggregateFunction {
 
     public void test() throws Exception {
         deleteDb("functions");
+        testVersion();
         testFunctionTable();
         testArrayParameters();
         testDefaultConnection();
@@ -79,6 +81,20 @@ public class TestFunctions extends TestBase implements AggregateFunction {
         FileUtils.deleteRecursive(TEMP_DIR, true);
     }
 
+    private void testVersion() throws SQLException {
+        Connection conn = getConnection("functions");
+        Statement stat = conn.createStatement();
+        String query = "select version()";
+        ResultSet rs = stat.executeQuery(query);
+        assertTrue(rs.next());
+        String version = rs.getString(1);
+        assertEquals(Constants.getVersion(), version);
+        assertFalse(rs.next());
+        rs.close();
+        stat.close();
+        conn.close();
+    }
+
     private void testFunctionTable() throws SQLException {
         Connection conn = getConnection("functions");
         Statement stat = conn.createStatement();