Index: src/tclsqlite.c
==================================================================
--- src/tclsqlite.c
+++ src/tclsqlite.c
@@ -162,15 +162,22 @@
   IncrblobChannel *pIncrblob;/* Linked list of open incrblob channels */
   int nStep, nSort, nIndex;  /* Statistics for most recent operation */
   int nVMStep;               /* Another statistic for most recent operation */
   int nTransaction;          /* Number of nested [transaction] methods */
   int openFlags;             /* Flags used to open.  (SQLITE_OPEN_URI) */
+  unsigned int modeFlags;    /* Operating mode flags */
 #ifdef SQLITE_TEST
   int bLegacyPrepare;        /* True to use sqlite3_prepare() */
 #endif
 };
 
+/*
+** Valid values for SqliteDb.modeFlags
+*/
+#define SQLITE_TCLMODE_UNSETNULL  0x0001  /* Unset NULL array values in */
+                                          /*   db eval ARRAY SQL */
+
 struct IncrblobChannel {
   sqlite3_blob *pBlob;      /* sqlite3 blob handle */
   SqliteDb *pDb;            /* Associated database connection */
   int iSeek;                /* Current seek offset */
   Tcl_Channel channel;      /* Channel identifier */
@@ -1728,15 +1735,19 @@
     int i;
     int nCol;
     Tcl_Obj **apColName;
     dbEvalRowInfo(p, &nCol, &apColName);
     for(i=0; i<nCol; i++){
-      Tcl_Obj *pVal = dbEvalColumnValue(p, i);
       if( pArray==0 ){
-        Tcl_ObjSetVar2(interp, apColName[i], 0, pVal, 0);
+        Tcl_ObjSetVar2(interp, apColName[i], 0, dbEvalColumnValue(p,i), 0);
+      }else if( (p->pDb->modeFlags & SQLITE_TCLMODE_UNSETNULL)!=0
+             && sqlite3_column_type(p->pPreStmt->pStmt, i)==SQLITE_NULL 
+      ){
+        Tcl_UnsetVar2(interp, Tcl_GetString(pArray), 
+                      Tcl_GetString(apColName[i]), 0);
       }else{
-        Tcl_ObjSetVar2(interp, pArray, apColName[i], pVal, 0);
+        Tcl_ObjSetVar2(interp, pArray, apColName[i], dbEvalColumnValue(p,i), 0);
       }
     }
 
     /* The required interpreter variables are now populated with the data
     ** from the current row. If using NRE, schedule callbacks to evaluate
@@ -3307,10 +3318,11 @@
   char *zErrMsg;
   int i;
   const char *zFile;
   const char *zVfs = 0;
   int flags;
+  unsigned int modeFlags = 0;
   Tcl_DString translatedFilename;
 #if defined(SQLITE_HAS_CODEC) && !defined(SQLITE_OMIT_CODEC_FROM_TCL)
   void *pKey = 0;
   int nKey = 0;
 #endif
@@ -3397,19 +3409,28 @@
       if( b ){
         flags |= SQLITE_OPEN_URI;
       }else{
         flags &= ~SQLITE_OPEN_URI;
       }
+    }else if( strcmp(zArg, "-unsetnull")==0 ){
+      int b;
+      if( Tcl_GetBooleanFromObj(interp, objv[i+1], &b) ) return TCL_ERROR;
+      if( b ){
+        modeFlags |= SQLITE_TCLMODE_UNSETNULL;
+      }else{
+        modeFlags &= ~SQLITE_TCLMODE_UNSETNULL;
+      }
     }else{
       Tcl_AppendResult(interp, "unknown option: ", zArg, (char*)0);
       return TCL_ERROR;
     }
   }
   if( objc<3 || (objc&1)!=1 ){
     Tcl_WrongNumArgs(interp, 1, objv,
       "HANDLE FILENAME ?-vfs VFSNAME? ?-readonly BOOLEAN? ?-create BOOLEAN?"
       " ?-nomutex BOOLEAN? ?-fullmutex BOOLEAN? ?-uri BOOLEAN?"
+      " ?-unsetnull BOOLEAN?"
 #if defined(SQLITE_HAS_CODEC) && !defined(SQLITE_OMIT_CODEC_FROM_TCL)
       " ?-key CODECKEY?"
 #endif
     );
     return TCL_ERROR;
@@ -3441,10 +3462,11 @@
     sqlite3_free(zErrMsg);
     return TCL_ERROR;
   }
   p->maxStmt = NUM_PREPARED_STMTS;
   p->openFlags = flags & SQLITE_OPEN_URI;
+  p->modeFlags = modeFlags;
   p->interp = interp;
   zArg = Tcl_GetStringFromObj(objv[1], 0);
   if( DbUseNre() ){
     Tcl_NRCreateCommand(interp, zArg, DbObjCmdAdaptor, DbObjCmd,
                         (char*)p, DbDeleteCmd);

Index: test/tclsqlite.test
==================================================================
--- test/tclsqlite.test
+++ test/tclsqlite.test
@@ -20,11 +20,11 @@
 set testdir [file dirname $argv0]
 source $testdir/tester.tcl
 
 # Check the error messages generated by tclsqlite
 #
-set r "sqlite_orig HANDLE FILENAME ?-vfs VFSNAME? ?-readonly BOOLEAN? ?-create BOOLEAN? ?-nomutex BOOLEAN? ?-fullmutex BOOLEAN? ?-uri BOOLEAN?"
+set r "sqlite_orig HANDLE FILENAME ?-vfs VFSNAME? ?-readonly BOOLEAN? ?-create BOOLEAN? ?-nomutex BOOLEAN? ?-fullmutex BOOLEAN? ?-uri BOOLEAN? ?-unsetnull BOOLEAN?"
 if {[sqlite3 -has-codec]} {
   append r " ?-key CODECKEY?"
 }
 do_test tcl-1.1 {
   set v [catch {sqlite3 bogus} msg]
@@ -662,12 +662,47 @@
 } {1}
 do_test tcl-15.5 {
   db exists {SELECT a FROM t1 WHERE a>3}
 } {0}
 
-
-
-
-
-
+# 2017-06-26: Different behavior with "-unsetnull 1" versus "-unsetnull 0"
+#
+# In the "db eval SQL ARRAY" form, NULL results cause the corresponding
+# array entry to be unset with -unsetnull 1.  With -unsetnull 0, the NULL
+# results cause the array entry to be filled with the [db nullvalue] string.
+# The -unsetnull 0 version is the default, for legacy compatibility.
+#
+catch {db close}
+forcedelete test.db
+sqlite3 db test.db
+do_execsql_test tcl-16.100 {
+  CREATE TABLE t1(a,b);
+  INSERT INTO t1 VALUES(1,2),(2,NULL),(3,'xyz');
+}
+do_test tcl-16.101 {
+  set res {}
+  unset -nocomplain x
+  db eval {SELECT * FROM t1} x {
+    lappend res $x(a) [array names x]
+  }
+  set res
+} {1 {a b *} 2 {a b *} 3 {a b *}}
+sqlite3 db test.db -unsetnull 0
+do_test tcl-16.102 {
+  set res {}
+  unset -nocomplain x
+  db eval {SELECT * FROM t1} x {
+    lappend res $x(a) [array names x]
+  }
+  set res
+} {1 {a b *} 2 {a b *} 3 {a b *}}
+sqlite3 db test.db -unsetnull 1
+do_test tcl-16.103 {
+  set res {}
+  unset -nocomplain x
+  db eval {SELECT * FROM t1} x {
+    lappend res $x(a) [array names x]
+  }
+  set res
+} {1 {a b *} 2 {a *} 3 {a b *}}
 
 finish_test