MDEV-36319: Wrong result json_table

Analysis:
Json path comparison logic was incorrect.

Author: mariadb-RuchaDeodhar

mysql-test/main/func_json.result

@@ -2692,4 +2692,75 @@ json_detailed('[[123],456]')
 SELECT JSON_VALUE(JSON_OBJECT("a", ""), '$.a') = "" AS not_null;
 not_null
 1
+#
+# MDEV-36319: Wrong result json_table
+#
+SET @JSON='
+{
+  "SZ": [
+    {
+      "NAME": "S0",
+      "OFFERS": [
+        {
+          "NAME": "S0A0"
+        }
+      ]
+    },
+    {
+      "NAME": "S1",
+      "OFFERS": [
+        {
+          "NAME": "S1A0"
+        },
+        {
+          "NAME": "S1A1"
+        }
+      ]
+    },
+    {
+      "NAME": "S2",
+      "OFFERS": [
+        {
+          "NAME": "S2A0"
+        }
+      ]
+    },
+    {
+      "NAME": "S3",
+      "OFFERS": [
+        {
+          "NAME": "S3A0"
+        }
+      ]
+    },
+    {
+      "NAME": "S4",
+      "OFFERS": [
+        {
+          "NAME": "S4A0"
+        }
+      ]
+    },
+    {
+      "NAME": "S5",
+      "OFFERS": [
+        {
+          "NAME": "S5A0"
+        }
+      ]
+    }
+  ]
+}
+ 
+'
+;
+# Should return EMPTY result
+SELECT * FROM json_table(@JSON, '$.SZ[0].OFFERS[1]' 
+COLUMNS(NAME VARCHAR(30) PATH '$.NAME')) AS t_sz;
+NAME
+# Should return S1A1
+SELECT * FROM json_table(@JSON, '$.SZ[1].OFFERS[1]' 
+COLUMNS(NAME VARCHAR(30) PATH '$.NAME')) AS t_sz;
+NAME
+S1A1
 # End of 10.11 Test

mysql-test/main/func_json.test

@@ -1953,4 +1953,76 @@ select json_detailed('[[123],456]');
 
 SELECT JSON_VALUE(JSON_OBJECT("a", ""), '$.a') = "" AS not_null;
 
+--echo #
+--echo # MDEV-36319: Wrong result json_table
+--echo #
+
+SET @JSON='
+{
+  "SZ": [
+    {
+      "NAME": "S0",
+      "OFFERS": [
+        {
+          "NAME": "S0A0"
+        }
+      ]
+    },
+    {
+      "NAME": "S1",
+      "OFFERS": [
+        {
+          "NAME": "S1A0"
+        },
+        {
+          "NAME": "S1A1"
+        }
+      ]
+    },
+    {
+      "NAME": "S2",
+      "OFFERS": [
+        {
+          "NAME": "S2A0"
+        }
+      ]
+    },
+    {
+      "NAME": "S3",
+      "OFFERS": [
+        {
+          "NAME": "S3A0"
+        }
+      ]
+    },
+    {
+      "NAME": "S4",
+      "OFFERS": [
+        {
+          "NAME": "S4A0"
+        }
+      ]
+    },
+    {
+      "NAME": "S5",
+      "OFFERS": [
+        {
+          "NAME": "S5A0"
+        }
+      ]
+    }
+  ]
+}
+ 
+'
+;
+ 
+--echo # Should return EMPTY result
+SELECT * FROM json_table(@JSON, '$.SZ[0].OFFERS[1]' 
+COLUMNS(NAME VARCHAR(30) PATH '$.NAME')) AS t_sz;
+ 
+--echo # Should return S1A1
+SELECT * FROM json_table(@JSON, '$.SZ[1].OFFERS[1]' 
+COLUMNS(NAME VARCHAR(30) PATH '$.NAME')) AS t_sz;
+
 --echo # End of 10.11 Test

sql/item_jsonfunc.cc

@@ -206,24 +206,23 @@ int json_path_parts_compare(
     {
       if (b->type & JSON_PATH_ARRAY)
       {
-        int res= 0, corrected_n_item_a= 0;
-        if (array_sizes)
-          corrected_n_item_a= a->n_item < 0 ?
-                                array_sizes[b-temp_b] + a->n_item : a->n_item;
-        if (a->type & JSON_PATH_ARRAY_RANGE)
+        int res = 0;
+        if (a->type & JSON_PATH_WILD)
+          res = 1;
+        else if (a->type & JSON_PATH_ARRAY_RANGE && array_sizes)
         {
-          int corrected_n_item_end_a= 0;
-          if (array_sizes)
-            corrected_n_item_end_a= a->n_item_end < 0 ?
-                                    array_sizes[b-temp_b] + a->n_item_end :
-                                    a->n_item_end;
-          res= b->n_item >= corrected_n_item_a &&
-                b->n_item <= corrected_n_item_end_a;
+            int start = (a->n_item >= 0) ? a->n_item
+                         : array_sizes[b - temp_b] + a->n_item;
+            int end   = (a->n_item_end >= 0) ? a->n_item_end
+                                   : array_sizes[b - temp_b] + a->n_item_end;
+            res = (b->n_item >= start && b->n_item <= end);
         }
-        else
-         res= corrected_n_item_a == b->n_item;
+        else if (a->n_item >= 0)
+          res = (a->n_item == b->n_item);
+        else if (a->n_item < 0 && array_sizes)
+          res = (a->n_item == b->n_item - array_sizes[b - temp_b]);
 
-        if ((a->type & JSON_PATH_WILD) || res)
+        if (res)
           goto step_fits;
         goto step_failed;
       }