diff --git a/manifest b/manifest
index 597a6be6c1..a054ecee7a 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Restrict\sthe\sRANDOM()\sfunction\sto\shave\szero\sarguments.\s\sTicket\s#3627.\s(CVS\s6229)
-D 2009-02-02T01:50:40
+C Update\sthe\sSUBSTR\sfunction\sso\sthat\sworks\sconsistently\swhen\sthe\n2nd\sparameter\sis\s0.\s\sTicket\s#3628.\s(CVS\s6230)
+D 2009-02-02T16:32:55
 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
 F Makefile.in 3871d308188cefcb7c5ab20da4c7b6aad023bc52
 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -113,7 +113,7 @@ F src/date.c 870770dde3fb56772ab247dfb6a6eda44d16cfbc
 F src/delete.c 6249005bdd8f85db6ec5f31ddb5c07de023693cc
 F src/expr.c 76dc3dc83b56ab8db50a772714fac49def8bbf12
 F src/fault.c dc88c821842157460750d2d61a8a8b4197d047ff
-F src/func.c a3aac94811d3d02ba9f4e79b429d011c3e921910
+F src/func.c f58648e196e86a1c7dfced3f1c82a7fbc714ebd0
 F src/global.c ab003581ea4ff193cfe17a00e1303bc51db619a5
 F src/hash.c 5824e6ff7ba78cd34c8d6cd724367713583e5b55
 F src/hash.h 28f38ebb1006a5beedcb013bcdfe31befe7437ae
@@ -538,7 +538,7 @@ F test/speed4p.test 0e51908951677de5a969b723e03a27a1c45db38b
 F test/sqllimits1.test 2f7ca3c7e7cef39a9c499e941e98b7f1708c4780
 F test/subquery.test b524f57c9574b2c0347045b4510ef795d4686796
 F test/subselect.test d24fd8757daf97dafd2e889c73ea4c4272dcf4e4
-F test/substr.test d08879fe398c4d2d332cbf8f5a112861635e3278
+F test/substr.test c23b84173371337f6b847ef2ede100bdded0fbec
 F test/sync.test ded6b39d8d8ca3c0c5518516c6371b3316d3e3a3
 F test/table.test 0aac9468b69d2683e68ee2682cdae28d82a453ec
 F test/tableapi.test 505031f15b18a750184d967d2c896cf88fcc969c
@@ -693,7 +693,7 @@ F tool/speedtest16.c c8a9c793df96db7e4933f0852abb7a03d48f2e81
 F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
-P 779fce82b7a89b972da488ce8bd35e23ca120c04
-R 451a04d06310737a09d46869e6ee15cb
+P b8b546b6ed799dc1621ef7b06273249af1042fb2
+R b631440e88a8d4df13cea097fdad8929
 U drh
-Z e2350e0a9b291ec6aab2df9bc3d08f44
+Z bb04b6d0ebe7bcb9aeeb21b9182eef4e
diff --git a/manifest.uuid b/manifest.uuid
index 9c6ac67408..e6b16f01f6 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-b8b546b6ed799dc1621ef7b06273249af1042fb2
\ No newline at end of file
+5fc125d362df4b8525c7e1ab34a14f505756af24
\ No newline at end of file
diff --git a/src/func.c b/src/func.c
index 4d4c8590ff..d92fa5bbf0 100644
--- a/src/func.c
+++ b/src/func.c
@@ -16,7 +16,7 @@
 ** sqliteRegisterBuildinFunctions() found at the bottom of the file.
 ** All other code has file scope.
 **
-** $Id: func.c,v 1.215 2009/02/02 01:50:40 drh Exp $
+** $Id: func.c,v 1.216 2009/02/02 16:32:55 drh Exp $
 */
 #include "sqliteInt.h"
 #include <stdlib.h>
@@ -43,7 +43,7 @@ static void minmaxFunc(
   int iBest;
   CollSeq *pColl;
 
-  if( argc==0 ) return;
+  assert( argc>1 );
   mask = sqlite3_user_data(context)==0 ? 0 : -1;
   pColl = sqlite3GetFuncCollSeq(context);
   assert( pColl );
@@ -53,6 +53,7 @@ static void minmaxFunc(
   for(i=1; i<argc; i++){
     if( sqlite3_value_type(argv[i])==SQLITE_NULL ) return;
     if( (sqlite3MemCompare(argv[iBest], argv[i], pColl)^mask)>=0 ){
+      testcase( mask==0 );
       iBest = i;
     }
   }
@@ -70,11 +71,11 @@ static void typeofFunc(
   const char *z = 0;
   UNUSED_PARAMETER(NotUsed);
   switch( sqlite3_value_type(argv[0]) ){
-    case SQLITE_NULL:    z = "null";    break;
     case SQLITE_INTEGER: z = "integer"; break;
     case SQLITE_TEXT:    z = "text";    break;
     case SQLITE_FLOAT:   z = "real";    break;
     case SQLITE_BLOB:    z = "blob";    break;
+    default:             z = "null";    break;
   }
   sqlite3_result_text(context, z, -1, SQLITE_STATIC);
 }
@@ -169,6 +170,7 @@ static void substrFunc(
   int len;
   int p0type;
   i64 p1, p2;
+  int negP2 = 0;
 
   assert( argc==3 || argc==2 );
   if( sqlite3_value_type(argv[1])==SQLITE_NULL
@@ -193,6 +195,10 @@ static void substrFunc(
   p1 = sqlite3_value_int(argv[1]);
   if( argc==3 ){
     p2 = sqlite3_value_int(argv[2]);
+    if( p2<0 ){
+      p2 = -p2;
+      negP2 = 1;
+    }
   }else{
     p2 = sqlite3_context_db_handle(context)->aLimit[SQLITE_LIMIT_LENGTH];
   }
@@ -200,19 +206,22 @@ static void substrFunc(
     p1 += len;
     if( p1<0 ){
       p2 += p1;
+      if( p2<0 ) p2 = 0;
       p1 = 0;
     }
   }else if( p1>0 ){
     p1--;
+  }else if( p2>0 ){
+    p2--;
   }
-  if( p2<0 ){
-    p1 += p2;
-    p2 = -p2;
+  if( negP2 ){
+    p1 -= p2;
     if( p1<0 ){
       p2 += p1;
       p1 = 0;
     }
   }
+  assert( p1>=0 && p2>=0 );
   if( p1+p2>len ){
     p2 = len-p1;
   }
@@ -226,7 +235,6 @@ static void substrFunc(
     }
     sqlite3_result_text(context, (char*)z, (int)(z2-z), SQLITE_TRANSIENT);
   }else{
-    if( p2<0 ) p2 = 0;
     sqlite3_result_blob(context, (char*)&z[p1], (int)p2, SQLITE_TRANSIENT);
   }
 }
diff --git a/test/substr.test b/test/substr.test
index d780c1466e..0a3303d92e 100644
--- a/test/substr.test
+++ b/test/substr.test
@@ -11,7 +11,7 @@
 # This file implements regression tests for SQLite library.  The
 # focus of this file is testing the built-in SUBSTR() functions.
 #
-# $Id: substr.test,v 1.5 2009/02/01 19:42:38 drh Exp $
+# $Id: substr.test,v 1.6 2009/02/02 16:32:55 drh Exp $
 
 set testdir [file dirname $argv0]
 source $testdir/tester.tcl
@@ -66,7 +66,7 @@ substr-test 1.1 abcdefg 1 1 a
 substr-test 1.2 abcdefg 2 1 b
 substr-test 1.3 abcdefg 1 2 ab
 substr-test 1.4 abcdefg 1 100 abcdefg
-substr-test 1.5 abcdefg 0 1 a
+substr-test 1.5 abcdefg 0 2 a
 substr-test 1.6 abcdefg -1 1 g
 substr-test 1.7 abcdefg -1 10 g
 substr-test 1.8 abcdefg -5 3 cde
@@ -112,7 +112,7 @@ subblob-test 3.1 61626364656667 1 1 61
 subblob-test 3.2 61626364656667 2 1 62
 subblob-test 3.3 61626364656667 1 2 6162
 subblob-test 3.4 61626364656667 1 100 61626364656667
-subblob-test 3.5 61626364656667 0 1 61
+subblob-test 3.5 61626364656667 0 2 61
 subblob-test 3.6 61626364656667 -1 1 67
 subblob-test 3.7 61626364656667 -1 10 67
 subblob-test 3.8 61626364656667 -5 3 636465