fix: sql compare to undefined values

apps/emqx_rule_engine/src/emqx_rule_runtime.erl

@@ -216,10 +216,8 @@ match_conditions({}, _Data) ->
     true.
 
 %% comparing numbers against strings
-compare(Op, undefined, undefined) ->
+compare(Op, L, R) when L == undefined; R == undefined ->
-    do_compare(Op, undefined, undefined);
+    do_compare(Op, L, R);
-compare(_Op, L, R) when L == undefined; R == undefined ->
-    false;
 compare(Op, L, R) when is_number(L), is_binary(R) ->
     do_compare(Op, L, number(R));
 compare(Op, L, R) when is_binary(L), is_number(R) ->
@@ -232,10 +230,14 @@ compare(Op, L, R) ->
     do_compare(Op, L, R).
 
 do_compare('=', L, R) -> L == R;
+do_compare('>', L, R) when L == undefined; R == undefined -> false;
 do_compare('>', L, R) -> L > R;
+do_compare('<', L, R) when L == undefined; R == undefined -> false;
 do_compare('<', L, R) -> L < R;
-do_compare('<=', L, R) -> L =< R;
+do_compare('<=', L, R) ->
-do_compare('>=', L, R) -> L >= R;
+    do_compare('=', L, R) orelse do_compare('<', L, R);
+do_compare('>=', L, R) ->
+    do_compare('=', L, R) orelse do_compare('>', L, R);
 do_compare('<>', L, R) -> L /= R;
 do_compare('!=', L, R) -> L /= R;
 do_compare('=~', T, F) -> emqx_topic:match(T, F).

apps/emqx_rule_engine/test/emqx_rule_engine_SUITE.erl

@@ -126,6 +126,10 @@ groups() ->
        t_sqlparse_array_range_1,
        t_sqlparse_array_range_2,
        t_sqlparse_true_false,
+       t_sqlparse_compare_null_null,
+       t_sqlparse_compare_null_notnull,
+       t_sqlparse_compare_notnull_null,
+       t_sqlparse_compare,
        t_sqlparse_new_map,
        t_sqlparse_invalid_json
       ]},
@@ -2486,6 +2490,210 @@ t_sqlparse_true_false(_Config) ->
                    <<"c">> := [true]
                    }, Res00).
 
+-define(TEST_SQL(SQL),
+    emqx_rule_sqltester:test(
+        #{<<"rawsql">> => SQL,
+          <<"ctx">> => #{<<"payload">> => <<"">>,
+                         <<"topic">> => <<"t/a">>}})).
+t_sqlparse_compare_null_null(_Config) ->
+    %% test undefined == undefined
+    Sql00 = "select "
+            " a = b as c "
+            "from \"t/#\" ",
+    {ok, Res00} = ?TEST_SQL(Sql00),
+    ?assertMatch(#{<<"c">> := true
+                   }, Res00),
+
+    %% test undefined != undefined
+    Sql01 = "select "
+            " a != b as c "
+            "from \"t/#\" ",
+    {ok, Res01} = ?TEST_SQL(Sql01),
+    ?assertMatch(#{<<"c">> := false
+                   }, Res01),
+
+    %% test undefined > undefined
+    Sql02 = "select "
+            " a > b as c "
+            "from \"t/#\" ",
+    {ok, Res02} = ?TEST_SQL(Sql02),
+    ?assertMatch(#{<<"c">> := false
+                   }, Res02),
+
+    %% test undefined < undefined
+    Sql03 = "select "
+            " a < b as c "
+            "from \"t/#\" ",
+    {ok, Res03} = ?TEST_SQL(Sql03),
+    ?assertMatch(#{<<"c">> := false
+                   }, Res03),
+
+    %% test undefined <= undefined
+    Sql04 = "select "
+            " a <= b as c "
+            "from \"t/#\" ",
+    {ok, Res04} = ?TEST_SQL(Sql04),
+    ?assertMatch(#{<<"c">> := true
+                   }, Res04),
+
+    %% test undefined >= undefined
+    Sql05 = "select "
+            " a >= b as c "
+            "from \"t/#\" ",
+    {ok, Res05} = ?TEST_SQL(Sql05),
+    ?assertMatch(#{<<"c">> := true
+                   }, Res05).
+
+t_sqlparse_compare_null_notnull(_Config) ->
+    %% test undefined == b
+    Sql00 = "select "
+            " 'b' as b, a = b as c "
+            "from \"t/#\" ",
+    {ok, Res00} = ?TEST_SQL(Sql00),
+    ?assertMatch(#{<<"c">> := false
+                   }, Res00),
+
+    %% test undefined != b
+    Sql01 = "select "
+            " 'b' as b, a != b as c "
+            "from \"t/#\" ",
+    {ok, Res01} = ?TEST_SQL(Sql01),
+    ?assertMatch(#{<<"c">> := true
+                   }, Res01),
+
+    %% test undefined > b
+    Sql02 = "select "
+            " 'b' as b, a > b as c "
+            "from \"t/#\" ",
+    {ok, Res02} = ?TEST_SQL(Sql02),
+    ?assertMatch(#{<<"c">> := false
+                   }, Res02),
+
+    %% test undefined < b
+    Sql03 = "select "
+            " 'b' as b, a < b as c "
+            "from \"t/#\" ",
+    {ok, Res03} = ?TEST_SQL(Sql03),
+    ?assertMatch(#{<<"c">> := false
+                   }, Res03),
+
+    %% test undefined <= b
+    Sql04 = "select "
+            " 'b' as b, a <= b as c "
+            "from \"t/#\" ",
+    {ok, Res04} = ?TEST_SQL(Sql04),
+    ?assertMatch(#{<<"c">> := false
+                   }, Res04),
+
+    %% test undefined >= b
+    Sql05 = "select "
+            " 'b' as b, a >= b as c "
+            "from \"t/#\" ",
+    {ok, Res05} = ?TEST_SQL(Sql05),
+    ?assertMatch(#{<<"c">> := false
+                   }, Res05).
+
+t_sqlparse_compare_notnull_null(_Config) ->
+    %% test 'a' == undefined
+    Sql00 = "select "
+            " 'a' as a, a = b as c "
+            "from \"t/#\" ",
+    {ok, Res00} = ?TEST_SQL(Sql00),
+    ?assertMatch(#{<<"c">> := false
+                   }, Res00),
+
+    %% test 'a' != undefined
+    Sql01 = "select "
+            " 'a' as a, a != b as c "
+            "from \"t/#\" ",
+    {ok, Res01} = ?TEST_SQL(Sql01),
+    ?assertMatch(#{<<"c">> := true
+                   }, Res01),
+
+    %% test 'a' > undefined
+    Sql02 = "select "
+            " 'a' as a, a > b as c "
+            "from \"t/#\" ",
+    {ok, Res02} = ?TEST_SQL(Sql02),
+    ?assertMatch(#{<<"c">> := false
+                   }, Res02),
+
+    %% test 'a' < undefined
+    Sql03 = "select "
+            " 'a' as a, a < b as c "
+            "from \"t/#\" ",
+    {ok, Res03} = ?TEST_SQL(Sql03),
+    ?assertMatch(#{<<"c">> := false
+                   }, Res03),
+
+    %% test 'a' <= undefined
+    Sql04 = "select "
+            " 'a' as a, a <= b as c "
+            "from \"t/#\" ",
+    {ok, Res04} = ?TEST_SQL(Sql04),
+    ?assertMatch(#{<<"c">> := false
+                   }, Res04),
+
+    %% test 'a' >= undefined
+    Sql05 = "select "
+            " 'a' as a, a >= b as c "
+            "from \"t/#\" ",
+    {ok, Res05} = ?TEST_SQL(Sql05),
+    ?assertMatch(#{<<"c">> := false
+                   }, Res05).
+
+t_sqlparse_compare(_Config) ->
+    Sql00 = "select "
+            " 'a' as a, 'a' as b, a = b as c "
+            "from \"t/#\" ",
+    {ok, Res00} = ?TEST_SQL(Sql00),
+    ?assertMatch(#{<<"c">> := true
+                   }, Res00),
+
+    Sql01 = "select "
+            " is_null(a) as c "
+            "from \"t/#\" ",
+    {ok, Res01} = ?TEST_SQL(Sql01),
+    ?assertMatch(#{<<"c">> := true
+                   }, Res01),
+
+    Sql02 = "select "
+            " 1 as a, 2 as b, a < b as c "
+            "from \"t/#\" ",
+    {ok, Res02} = ?TEST_SQL(Sql02),
+    ?assertMatch(#{<<"c">> := true
+                   }, Res02),
+
+    Sql03 = "select "
+            " 1 as a, 2 as b, a > b as c "
+            "from \"t/#\" ",
+    {ok, Res03} = ?TEST_SQL(Sql03),
+    ?assertMatch(#{<<"c">> := false
+                   }, Res03),
+
+    Sql04 = "select "
+            " 1 as a, 2 as b, a = b as c "
+            "from \"t/#\" ",
+    {ok, Res04} = ?TEST_SQL(Sql04),
+    ?assertMatch(#{<<"c">> := false
+                   }, Res04),
+
+    %% test 'a' >= undefined
+    Sql05 = "select "
+            " 1 as a, 2 as b, a >= b as c "
+            "from \"t/#\" ",
+    {ok, Res05} = ?TEST_SQL(Sql05),
+    ?assertMatch(#{<<"c">> := false
+                   }, Res05),
+
+    %% test 'a' >= undefined
+    Sql06 = "select "
+            " 1 as a, 2 as b, a <= b as c "
+            "from \"t/#\" ",
+    {ok, Res06} = ?TEST_SQL(Sql06),
+    ?assertMatch(#{<<"c">> := true
+                   }, Res06).
+
 t_sqlparse_new_map(_Config) ->
     %% construct a range without 'as'
     Sql00 = "select "