Parse DB2's special registers only in DB2 mode

h2/src/main/org/h2/command/Parser.java

@@ -3377,16 +3377,8 @@ public class Parser {
                     r = readFunctionWithoutParameters("LOCALTIME");
                 } else if (equalsToken("SYSTIME", name)) {
                     r = readFunctionWithoutParameters("CURRENT_TIME");
-                } else if (equalsToken("CURRENT", name)) {
-                    if (readIf("TIMESTAMP")) {
-                        r = readFunctionWithoutParameters("CURRENT_TIMESTAMP");
-                    } else if (readIf("TIME")) {
-                        r = readFunctionWithoutParameters("CURRENT_TIME");
-                    } else if (readIf("DATE")) {
-                        r = readFunctionWithoutParameters("CURRENT_DATE");
-                    } else {
-                        r = new ExpressionColumn(database, null, null, name);
-                    }
+                } else if (database.getMode().getEnum() == ModeEnum.DB2 && equalsToken("CURRENT", name)) {
+                    r = parseDB2SpecialRegisters(name);
                 } else if (equalsToken("NEXT", name) && readIf("VALUE")) {
                     read(FOR);
                     Sequence sequence = readSequence();
@@ -3588,6 +3580,24 @@ public class Parser {
         return r;
     }
 
+    private Expression parseDB2SpecialRegisters(String name) {
+        // Only "CURRENT" name is supported
+        if (readIf("TIMESTAMP")) {
+            if (readIf(WITH)) {
+                read("TIME");
+                read("ZONE");
+                return readFunctionWithoutParameters("CURRENT_TIMESTAMP");
+            }
+            return readFunctionWithoutParameters("LOCALTIMESTAMP");
+        } else if (readIf("TIME")) {
+            return readFunctionWithoutParameters("CURRENT_TIME");
+        } else if (readIf("DATE")) {
+            return readFunctionWithoutParameters("CURRENT_DATE");
+        }
+        // No match, parse CURRENT as a column
+        return new ExpressionColumn(database, null, null, name);
+    }
+
     private Expression readCase() {
         if (readIf("END")) {
             readIf("CASE");

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

@@ -561,6 +561,19 @@ public class TestCompatibility extends TestDb {
                 "select date from test where date = '2014-04-05-09.48.28.020005'");
         assertResult("2014-04-05 09:48:28.020005", stat,
                 "select date from test where date = '2014-04-05 09:48:28.020005'");
+
+        // Test limited support for DB2's special registers
+
+        // Standard SQL functions like LOCALTIMESTAMP, CURRENT_TIMESTAMP and
+        // others are used to compare values, their implementation in H2 is
+        // compatible with standard, but may be not really compatible with DB2.
+        assertResult("TRUE", stat, "SELECT LOCALTIMESTAMP = CURRENT TIMESTAMP");
+        assertResult("TRUE", stat, "SELECT CAST(LOCALTIMESTAMP AS VARCHAR) = CAST(CURRENT TIMESTAMP AS VARCHAR)");
+        assertResult("TRUE", stat, "SELECT CURRENT_TIMESTAMP = CURRENT TIMESTAMP WITH TIME ZONE");
+        assertResult("TRUE", stat,
+                "SELECT CAST(CURRENT_TIMESTAMP AS VARCHAR) = CAST(CURRENT TIMESTAMP WITH TIME ZONE AS VARCHAR)");
+        assertResult("TRUE", stat, "SELECT CURRENT_TIME = CURRENT TIME");
+        assertResult("TRUE", stat, "SELECT CURRENT_DATE = CURRENT DATE");
     }
 
     private void testDerby() throws SQLException {