NULL values are distinct. A comparison involving a NULL is always false.

Operations on a NULL value yield a NULL result.  This change makes SQLite
operate more like the SQL spec, but it may break existing applications that
assumed the old behavior.  All the old tests pass but we still need to add
new tests to better verify the new behavior.  Fix for ticket #44. (CVS 589)

FossilOrigin-Name: 9051173742f1b0e15a809d12a0c9c98fd2c4614d

src/vdbe.h

@@ -15,7 +15,7 @@
 ** or VDBE.  The VDBE implements an abstract machine that runs a
 ** simple program to access and modify the underlying database.
 **
-** $Id: vdbe.h,v 1.52 2002/05/23 22:07:03 drh Exp $
+** $Id: vdbe.h,v 1.53 2002/05/26 20:54:34 drh Exp $
 */
 #ifndef _SQLITE_VDBE_H_
 #define _SQLITE_VDBE_H_
@@ -157,53 +157,54 @@ typedef struct VdbeOp VdbeOp;
 
 #define OP_Goto               76
 #define OP_If                 77
-#define OP_Halt               78
+#define OP_IfNot              78
+#define OP_Halt               79
 
-#define OP_ColumnCount        79
-#define OP_ColumnName         80
-#define OP_Callback           81
-#define OP_NullCallback       82
+#define OP_ColumnCount        80
+#define OP_ColumnName         81
+#define OP_Callback           82
+#define OP_NullCallback       83
 
-#define OP_Integer            83
-#define OP_String             84
-#define OP_Pop                85
-#define OP_Dup                86
-#define OP_Pull               87
-#define OP_Push               88
-#define OP_MustBeInt          89
+#define OP_Integer            84
+#define OP_String             85
+#define OP_Pop                86
+#define OP_Dup                87
+#define OP_Pull               88
+#define OP_Push               89
+#define OP_MustBeInt          90
 
-#define OP_Add                90
-#define OP_AddImm             91
-#define OP_Subtract           92
-#define OP_Multiply           93
-#define OP_Divide             94
-#define OP_Remainder          95
-#define OP_BitAnd             96
-#define OP_BitOr              97
-#define OP_BitNot             98
-#define OP_ShiftLeft          99
-#define OP_ShiftRight        100
-#define OP_AbsValue          101
-#define OP_Eq                102
-#define OP_Ne                103
-#define OP_Lt                104
-#define OP_Le                105
-#define OP_Gt                106
-#define OP_Ge                107
-#define OP_IsNull            108
-#define OP_NotNull           109
-#define OP_Negative          110
-#define OP_And               111
-#define OP_Or                112
-#define OP_Not               113
-#define OP_Concat            114
-#define OP_Noop              115
-#define OP_Function          116
+#define OP_Add                91
+#define OP_AddImm             92
+#define OP_Subtract           93
+#define OP_Multiply           94
+#define OP_Divide             95
+#define OP_Remainder          96
+#define OP_BitAnd             97
+#define OP_BitOr              98
+#define OP_BitNot             99
+#define OP_ShiftLeft         100
+#define OP_ShiftRight        101
+#define OP_AbsValue          102
+#define OP_Eq                103
+#define OP_Ne                104
+#define OP_Lt                105
+#define OP_Le                106
+#define OP_Gt                107
+#define OP_Ge                108
+#define OP_IsNull            109
+#define OP_NotNull           110
+#define OP_Negative          111
+#define OP_And               112
+#define OP_Or                113
+#define OP_Not               114
+#define OP_Concat            115
+#define OP_Noop              116
+#define OP_Function          117
 
-#define OP_Limit             117
+#define OP_Limit             118
 
 
-#define OP_MAX               117
+#define OP_MAX               118
 
 /*
 ** Prototypes for the VDBE interface.  See comments on the implementation