MDEV-12985: syntax added for the percentile_cont and percentile_disc functions

sql/lex.h

@@ -701,6 +701,7 @@ static SYMBOL symbols[] = {
   { "WHILE",            SYM(WHILE_SYM)},
   { "WINDOW",           SYM(WINDOW_SYM)}, 
   { "WITH",		SYM(WITH)},
+  { "WITHIN",   SYM(WITHIN)},
   { "WORK",		SYM(WORK_SYM)},
   { "WRAPPER",		SYM(WRAPPER_SYM)},
   { "WRITE",		SYM(WRITE_SYM)},
@@ -743,6 +744,8 @@ static SYMBOL sql_functions[] = {
   { "NTILE",            SYM(NTILE_SYM)},
   { "POSITION",		SYM(POSITION_SYM)},
   { "PERCENT_RANK",     SYM(PERCENT_RANK_SYM)},
+  { "PERCENTILE_CONT",  SYM(PERCENTILE_CONT_SYM)},
+  { "PERCENTILE_DISC",  SYM(PERCENTILE_DISC_SYM)},
   { "RANK",             SYM(RANK_SYM)},
   { "ROW_NUMBER",       SYM(ROW_NUMBER_SYM)},
   { "SESSION_USER",     SYM(USER_SYM)},

sql/sql_yacc.yy

@@ -1328,6 +1328,8 @@ bool my_yyoverflow(short **a, YYSTYPE **b, ulong *yystacksize);
 %token  PARTITIONING_SYM
 %token  PASSWORD_SYM
 %token  PERCENT_RANK_SYM
+%token  PERCENTILE_CONT_SYM
+%token  PERCENTILE_DISC_SYM
 %token  PERSISTENT_SYM
 %token  PHASE_SYM
 %token  PLUGINS_SYM
@@ -1574,6 +1576,7 @@ bool my_yyoverflow(short **a, YYSTYPE **b, ulong *yystacksize);
 %token  WINDOW_SYM
 %token  WHILE_SYM
 %token  WITH                          /* SQL-2003-R */
+%token  WITHIN
 %token  WITH_CUBE_SYM                 /* INTERNAL */
 %token  WITH_ROLLUP_SYM               /* INTERNAL */
 %token  WORK_SYM                      /* SQL-2003-N */
@@ -1733,6 +1736,7 @@ bool my_yyoverflow(short **a, YYSTYPE **b, ulong *yystacksize);
         window_func_expr
         window_func
         simple_window_func
+        inverse_distribution_function
         function_call_keyword
         function_call_nonkeyword
         function_call_generic
@@ -1951,7 +1955,6 @@ END_OF_INPUT
 
 %type <spvar_definition> row_field_name row_field_definition
 %type <spvar_definition_list> row_field_definition_list row_type_body
-
 %type <NONE> opt_window_clause window_def_list window_def window_spec
 %type <lex_str_ptr> window_name
 %type <NONE> opt_window_ref opt_window_frame_clause
@@ -9374,6 +9377,7 @@ column_default_non_parenthesized_expr:
         | variable
         | sum_expr
         | window_func_expr
+        | inverse_distribution_function
         | ROW_SYM '(' expr ',' expr_list ')'
           {
             $5->push_front($3, thd->mem_root);
@@ -10693,6 +10697,25 @@ simple_window_func:
           }
         ;
 
+
+inverse_distribution_function:
+        inverse_distribution_function_type '(' expr ')' WITHIN GROUP_SYM
+        '(' order_by_single_element_list ')' OVER_SYM '(' opt_window_ref opt_window_partition_clause ')'
+        {
+           my_yyabort_error((ER_VIEW_SELECT_VARIABLE, MYF(0)));
+        };
+
+inverse_distribution_function_type:
+     PERCENTILE_CONT_SYM
+      {}
+    |PERCENTILE_DISC_SYM
+    {}
+    ;
+
+order_by_single_element_list:
+    ORDER_SYM BY order_ident order_dir
+    ;
+
 window_name:
           ident
           {