MDEV-22164 revert "make THAN optional"

mysql-test/suite/parts/r/alter_table.result

@@ -366,8 +366,7 @@ drop table validation;
 create table t (a int primary key);
 create table tp (a int primary key) partition by range (a) (
 partition p0 values less than (100),
-# Cunning syntax (same as above)
-p1 values less (300));
+p1 values less than (300));
 insert into t values (1), (99);
 insert into tp values (2), (200);
 select * from t order by a;
@@ -486,11 +485,11 @@ a
 200
 drop prepare validation;
 drop prepare without_validation;
-alter table tp convert table t to partition p2 values less (maxvalue);
+alter table tp convert table t to partition p2 values less than (maxvalue);
 ERROR HY000: Found a row that does not match the partition
-alter table tp convert table t to partition p2 values less (maxvalue) with validation;
+alter table tp convert table t to partition p2 values less than (maxvalue) with validation;
 ERROR HY000: Found a row that does not match the partition
-alter table tp convert table t to partition p2 values less (maxvalue) without validation;
+alter table tp convert table t to partition p2 values less than (maxvalue) without validation;
 select * from tp partition (p0) order by a;
 a
 2

mysql-test/suite/parts/t/alter_table.test

@@ -331,8 +331,7 @@ create table t (a int primary key);
 
 create table tp (a int primary key) partition by range (a) (
   partition p0 values less than (100),
-  # Cunning syntax (same as above)
-  p1 values less (300));
+  p1 values less than (300));
 
 insert into t values (1), (99);
 insert into tp values (2), (200);
@@ -407,10 +406,10 @@ drop prepare without_validation;
 
 # CONVERT IN
 --error ER_ROW_DOES_NOT_MATCH_PARTITION
-alter table tp convert table t to partition p2 values less (maxvalue);
+alter table tp convert table t to partition p2 values less than (maxvalue);
 --error ER_ROW_DOES_NOT_MATCH_PARTITION
-alter table tp convert table t to partition p2 values less (maxvalue) with validation;
-alter table tp convert table t to partition p2 values less (maxvalue) without validation;
+alter table tp convert table t to partition p2 values less than (maxvalue) with validation;
+alter table tp convert table t to partition p2 values less than (maxvalue) without validation;
 select * from tp partition (p0) order by a;
 select * from tp partition (p1) order by a;
 select * from tp partition (p2) order by a;

sql/sql_yacc.yy

@@ -4960,10 +4960,6 @@ part_name:
           }
         ;
 
-opt_than:
-          /* empty */
-          | THAN_SYM;
-
 opt_part_values:
           /* empty */
           {
@@ -4981,7 +4977,7 @@ opt_part_values:
             else
               part_info->part_type= HASH_PARTITION;
           }
-        | VALUES_LESS_SYM opt_than
+        | VALUES_LESS_SYM THAN_SYM
           {
             LEX *lex= Lex;
             partition_info *part_info= lex->part_info;