Index: src/tclsqlite.c
==================================================================
--- src/tclsqlite.c
+++ src/tclsqlite.c
@@ -9,11 +9,11 @@
 **    May you share freely, never taking more than you give.
 **
 *************************************************************************
 ** A TCL Interface to SQLite
 **
-** $Id: tclsqlite.c,v 1.135 2005/12/07 06:27:44 danielk1977 Exp $
+** $Id: tclsqlite.c,v 1.136 2005/12/10 21:19:05 drh Exp $
 */
 #ifndef NO_TCL     /* Omit this whole file if TCL is unavailable */
 
 #include "sqliteInt.h"
 #include "hash.h"
@@ -619,25 +619,26 @@
   static const char *DB_strs[] = {
     "authorizer",         "busy",              "cache",
     "changes",            "close",             "collate",
     "collation_needed",   "commit_hook",       "complete",
     "copy",               "errorcode",         "eval",
-    "function",           "last_insert_rowid", "nullvalue",
-    "onecolumn",          "profile",           "progress",
-    "rekey",              "timeout",           "total_changes",
-    "trace",              "transaction",       "version",
-    0                    
+    "exists",             "function",          "last_insert_rowid",
+    "nullvalue",          "onecolumn",         "profile",
+    "progress",           "rekey",             "timeout",
+    "total_changes",      "trace",             "transaction",
+    "version",            0                    
   };
   enum DB_enum {
     DB_AUTHORIZER,        DB_BUSY,             DB_CACHE,
     DB_CHANGES,           DB_CLOSE,            DB_COLLATE,
     DB_COLLATION_NEEDED,  DB_COMMIT_HOOK,      DB_COMPLETE,
     DB_COPY,              DB_ERRORCODE,        DB_EVAL,
-    DB_FUNCTION,          DB_LAST_INSERT_ROWID,DB_NULLVALUE,
-    DB_ONECOLUMN,         DB_PROFILE,          DB_PROGRESS,
-    DB_REKEY,             DB_TIMEOUT,          DB_TOTAL_CHANGES,
-    DB_TRACE,             DB_TRANSACTION,      DB_VERSION
+    DB_EXISTS,            DB_FUNCTION,         DB_LAST_INSERT_ROWID,
+    DB_NULLVALUE,         DB_ONECOLUMN,        DB_PROFILE,
+    DB_PROGRESS,          DB_REKEY,            DB_TIMEOUT,
+    DB_TOTAL_CHANGES,     DB_TRACE,            DB_TRANSACTION,
+    DB_VERSION
   };
   /* don't leave trailing commas on DB_enum, it confuses the AIX xlc compiler */
 
   if( objc<2 ){
     Tcl_WrongNumArgs(interp, 1, objv, "SUBCOMMAND ...");
@@ -1134,11 +1135,12 @@
   **
   ** The onecolumn method is the equivalent of:
   **     lindex [$db eval $sql] 0
   */
   case DB_ONECOLUMN:
-  case DB_EVAL: {
+  case DB_EVAL:
+  case DB_EXISTS: {
     char const *zSql;      /* Next SQL statement to execute */
     char const *zLeft;     /* What is left after first stmt in zSql */
     sqlite3_stmt *pStmt;   /* Compiled SQL statment */
     Tcl_Obj *pArray;       /* Name of array into which results are written */
     Tcl_Obj *pScript;      /* Script to run for each result set */
@@ -1147,23 +1149,26 @@
     Tcl_Obj *aParm[10];    /* Static space for apParm[] in the common case */
     Tcl_Obj *pRet;         /* Value to be returned */
     SqlPreparedStmt *pPreStmt;  /* Pointer to a prepared statement */
     int rc2;
 
-    if( choice==DB_ONECOLUMN ){
-      if( objc!=3 ){
-        Tcl_WrongNumArgs(interp, 2, objv, "SQL");
-        return TCL_ERROR;
-      }
-      pRet = 0;
-    }else{
+    if( choice==DB_EVAL ){
       if( objc<3 || objc>5 ){
         Tcl_WrongNumArgs(interp, 2, objv, "SQL ?ARRAY-NAME? ?SCRIPT?");
         return TCL_ERROR;
       }
       pRet = Tcl_NewObj();
       Tcl_IncrRefCount(pRet);
+    }else{
+      if( objc!=3 ){
+        Tcl_WrongNumArgs(interp, 2, objv, "SQL");
+        return TCL_ERROR;
+      }
+      pRet = 0;
+      if( choice==DB_EXISTS ){
+        Tcl_SetObjResult(interp, Tcl_NewBooleanObj(0));
+      }
     }
     if( objc==3 ){
       pArray = pScript = 0;
     }else if( objc==4 ){
       pArray = 0;
@@ -1364,15 +1369,22 @@
               Tcl_ObjSetVar2(interp, apColName[i], 0, pVal, 0);
             }else{
               Tcl_ObjSetVar2(interp, pArray, apColName[i], pVal, 0);
             }
           }else if( choice==DB_ONECOLUMN ){
+            assert( pRet==0 );
             if( pRet==0 ){
               pRet = pVal;
               Tcl_IncrRefCount(pRet);
             }
             rc = TCL_BREAK;
+            i = nCol;
+          }else if( choice==DB_EXISTS ){
+            assert( pRet==0 );
+            Tcl_SetObjResult(interp, Tcl_NewBooleanObj(1));
+            rc = TCL_BREAK;
+            i = nCol;
           }else{
             Tcl_ListObjAppendElement(interp, pRet, pVal);
           }
         }
   

Index: test/tclsqlite.test
==================================================================
--- test/tclsqlite.test
+++ test/tclsqlite.test
@@ -13,11 +13,11 @@
 #
 # Actually, all tests are based on the TCL interface, so the main
 # interface is pretty well tested.  This file contains some addition
 # tests for fringe issues that the main test suite does not cover.
 #
-# $Id: tclsqlite.test,v 1.44 2005/08/29 23:00:05 drh Exp $
+# $Id: tclsqlite.test,v 1.45 2005/12/10 21:19:06 drh Exp $
 
 set testdir [file dirname $argv0]
 source $testdir/tester.tcl
 
 # Check the error messages generated by tclsqlite
@@ -32,11 +32,11 @@
   lappend v $msg
 } [list 1 "wrong # args: should be \"$r\""]
 do_test tcl-1.2 {
   set v [catch {db bogus} msg]
   lappend v $msg
-} {1 {bad option "bogus": must be authorizer, busy, cache, changes, close, collate, collation_needed, commit_hook, complete, copy, errorcode, eval, function, last_insert_rowid, nullvalue, onecolumn, profile, progress, rekey, timeout, total_changes, trace, transaction, or version}}
+} {1 {bad option "bogus": must be authorizer, busy, cache, changes, close, collate, collation_needed, commit_hook, complete, copy, errorcode, eval, exists, function, last_insert_rowid, nullvalue, onecolumn, profile, progress, rekey, timeout, total_changes, trace, transaction, or version}}
 do_test tcl-1.3 {
   execsql {CREATE TABLE t1(a int, b int)}
   execsql {INSERT INTO t1 VALUES(10,20)}
   set v [catch {
     db eval {SELECT * FROM t1} data {
@@ -432,7 +432,17 @@
   }]
 } {2}
 do_test tcl-10.13 {
   db eval {SELECT * FROM t4}
 } {1 2 3 4 5 6 7}
+
+do_test tcl-11.1 {
+  db exists {SELECT x,x*2,x+x FROM t4 WHERE x==4}
+} {1}
+do_test tcl-11.2 {
+  db exists {SELECT 0 FROM t4 WHERE x==4}
+} {1}
+do_test tcl-11.3 {
+  db exists {SELECT 1 FROM t4 WHERE x==8}
+} {0}
 
 finish_test