1 files changed, 135 insertions, 0 deletions
diff --git a/mysql-test/include/empty_string_literal.inc b/mysql-test/include/empty_string_literal.inc
new file mode 100644
index 00000000..5857c26d
--- /dev/null
+++ b/mysql-test/include/empty_string_literal.inc
@@ -0,0 +1,135 @@
+SET SESSION character_set_connection=latin2;
+SET SESSION character_set_client=cp1250;
+
+--disable_service_connection
+
+--echo #
+--echo # Test litteral
+--echo #
+
+#enable view protocol after fix MDEV-27871 and
+# it is necessary that the view protocol uses the same connection,
+# not util connection
+--disable_view_protocol
+
+SET sql_mode=@mode;
+select @@sql_mode;
+SELECT '',CHARSET(''), null, CHARSET(null), CAST(null as char(10)), CHARSET(CAST(null as char(10))), 'x', CHARSET('x');
+SELECT CHARSET(NULLIF('','')),NULLIF('','');
+SET sql_mode=default;
+SELECT '',CHARSET(''), null, CHARSET(null), CAST(null as char(10)), CHARSET(CAST(null as char(10))), 'x', CHARSET('x');
+SELECT CHARSET(NULLIF('','')),NULLIF('','');
+
+
+
+--echo #
+--echo # Test NCHAR litteral
+--echo #
+SET sql_mode=@mode;
+SELECT N'',CHARSET(N''), N'x', CHARSET(N'x');
+SELECT CHARSET(NULLIF(N'',N'')),NULLIF(N'',N'');
+SET sql_mode=default;
+SELECT N'',CHARSET(N''), N'x', CHARSET(N'x');
+SELECT CHARSET(NULLIF(N'',N'')),NULLIF(N'',N'');
+
+
+
+--echo #
+--echo # Test CHARSET prefix litteral
+--echo #
+SET sql_mode=@mode;
+SELECT _cp1250 '',CHARSET(_cp1250 ''), _cp1250 'x', CHARSET(_cp1250 'x');
+SELECT CHARSET(NULLIF(_cp1250 '',_cp1250 '')),NULLIF(_cp1250 '',_cp1250 '');
+SET sql_mode=default;
+SELECT _cp1250 '',CHARSET(_cp1250 ''), _cp1250 'x', CHARSET(_cp1250 'x');
+SELECT CHARSET(NULLIF(_cp1250 '',_cp1250 '')),NULLIF(_cp1250 '',_cp1250 '');
+
+
+SET sql_mode=@mode;
+
+--echo #
+--echo # Test litteral concat
+--echo #
+SELECT 'a' 'b';
+SELECT 'a' '';
+SELECT '' 'b';
+SELECT '' '';
+SELECT '' 'b' 'c';
+SELECT '' '' 'c';
+SELECT 'a' '' 'c';
+SELECT 'a' '' '';
+SELECT '' '' '';
+
+SELECT '' '' '',CHARSET('' '' '');
+SELECT _latin1'' '' '',CHARSET(_latin1'' '' '');
+SELECT N'' '' '',CHARSET(N'' '' '');
+
+--enable_view_protocol
+
+--echo #
+--echo # UNION - implicit group by
+--echo #
+SELECT 1, null
+UNION
+SELECT 1 , ''
+ORDER BY 1;
+
+SELECT 1, null
+UNION
+SELECT 1 , N''
+ORDER BY 1;
+
+SELECT 1, null
+UNION
+SELECT 1 , _cp1250 ''
+ORDER BY 1;
+
+# it is necessary that the view protocol uses the same connection,
+# not util connection
+--disable_view_protocol
+
+SELECT NULLIF(_cp1250 '',_cp1250 '')
+UNION
+SELECT NULLIF(N'',N'');
+
+--enable_view_protocol
+
+--error ER_CANT_AGGREGATE_2COLLATIONS
+SELECT 1 , _latin2 ''
+UNION
+SELECT 1 , _cp1250 '';
+
+SELECT 1, null
+UNION
+SELECT 1 , ''
+UNION
+SELECT 1 , N'';
+
+CREATE TABLE t1 (c1 INT,c2 VARCHAR(10));
+INSERT INTO t1 VALUES (1,'one');
+INSERT INTO t1 VALUES (1,'');
+INSERT INTO t1 VALUES (1,null);
+
+--echo #
+--echo # Test in a view
+--echo #
+CREATE VIEW v1
+    AS SELECT c1, c2
+         FROM t1
+       UNION
+       SELECT c1 , ''
+         FROM t1
+       ORDER BY 1,2;
+SELECT * FROM v1;
+
+SHOW CREATE VIEW v1;
+
+DROP VIEW v1;
+DROP TABLE t1;
+
+EXPLAIN EXTENDED SELECT '';
+EXPLAIN EXTENDED SELECT _latin1'';
+EXPLAIN EXTENDED SELECT N'';
+EXPLAIN EXTENDED SELECT '' '';
+
+--enable_service_connection