MDEV-12086 sql_mode=ORACLE: allow SELECT UNIQUE as a synonym for SELECT DISTINCT

mysql-test/suite/compat/oracle/r/misc.result

+SET sql_mode=ORACLE;
+#
+# MDEV-12086 sql_mode=ORACLE: allow SELECT UNIQUE as a synonym for SELECT DISTINCT
+#
+CREATE TABLE t1 (a INT);
+INSERT INTO t1 VALUES (10),(20),(20),(30),(30),(30);
+SELECT UNIQUE a FROM t1;
+a
+10
+20
+30
+DROP TABLE t1;

mysql-test/suite/compat/oracle/t/misc.test

+SET sql_mode=ORACLE;
+
+--echo #
+--echo # MDEV-12086 sql_mode=ORACLE: allow SELECT UNIQUE as a synonym for SELECT DISTINCT
+--echo #
+
+CREATE TABLE t1 (a INT);
+INSERT INTO t1 VALUES (10),(20),(20),(30),(30),(30);
+SELECT UNIQUE a FROM t1;
+DROP TABLE t1;

sql/sql_yacc_ora.yy

@@ -16194,6 +16194,7 @@ query_expression_option:
             Select->options|= SELECT_HIGH_PRIORITY;
           }
         | DISTINCT         { Select->options|= SELECT_DISTINCT; }
+        | UNIQUE_SYM       { Select->options|= SELECT_DISTINCT; }
         | SQL_SMALL_RESULT { Select->options|= SELECT_SMALL_RESULT; }
         | SQL_BIG_RESULT   { Select->options|= SELECT_BIG_RESULT; }
         | SQL_BUFFER_RESULT