MDEV-8704 Wrong result for SELECT..WHERE LENGTH(double_column)!=6 AND double_column=100e0

mysql-test/r/type_float.result

@@ -532,3 +532,98 @@ DROP TABLE t1,t2;
 #
 # End of 10.0 tests
 #
+#
+# MDEV-8704 Wrong result for SELECT..WHERE LENGTH(double_column)!=6 AND double_column=100e0
+#
+CREATE TABLE t1 (a DOUBLE(9,2));
+INSERT INTO t1 VALUES (100),(110);
+SELECT * FROM t1 WHERE LENGTH(a)!=6;
+a
+SELECT * FROM t1 WHERE LENGTH(a)!=6 AND a=100e0;
+a
+DROP TABLE t1;
+CREATE TABLE t1 (a DOUBLE);
+INSERT INTO t1 VALUES (100),(110);
+SELECT * FROM t1 WHERE LENGTH(a)!=6;
+a
+100
+110
+SELECT * FROM t1 WHERE LENGTH(a)!=6 AND a=100e0;
+a
+100
+EXPLAIN EXTENDED
+SELECT * FROM t1 WHERE LENGTH(a)!=6 AND a=100e0;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
+Warnings:
+Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where (`test`.`t1`.`a` = 100e0)
+EXPLAIN EXTENDED
+SELECT * FROM t1 WHERE LENGTH(a)!=RAND() AND a=100e0;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
+Warnings:
+Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where ((`test`.`t1`.`a` = 100e0) and (<cache>(length(100)) <> rand()))
+DROP TABLE t1;
+CREATE TABLE t1 (a DOUBLE(10,1));
+INSERT INTO t1 VALUES (1.1),(1.2),(1.3);
+SELECT * FROM t1 WHERE LENGTH(a)!=3;
+a
+SELECT * FROM t1 WHERE LENGTH(a)!=3 AND a=1.10e0;
+a
+EXPLAIN EXTENDED
+SELECT * FROM t1 WHERE LENGTH(a)!=3 AND a=1.10e0;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE
+Warnings:
+Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where 0
+# Notice 1.1 instead of 1.10 in the final WHERE condition
+EXPLAIN EXTENDED
+SELECT * FROM t1 WHERE LENGTH(a)!=RAND() AND a=1.10e0;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
+Warnings:
+Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where ((`test`.`t1`.`a` = 1.10e0) and (<cache>(length(1.1)) <> rand()))
+DROP TABLE t1;
+CREATE TABLE t1 (a DOUBLE(10,2));
+INSERT INTO t1 VALUES (1.1),(1.2),(1.3);
+SELECT * FROM t1 WHERE LENGTH(a)!=4;
+a
+SELECT * FROM t1 WHERE LENGTH(a)!=4 AND a=1.10e0;
+a
+EXPLAIN EXTENDED
+SELECT * FROM t1 WHERE LENGTH(a)!=4 AND a=1.10e0;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE
+Warnings:
+Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where 0
+# Notice 1.10 in the final WHERE condition
+EXPLAIN EXTENDED
+SELECT * FROM t1 WHERE LENGTH(a)!=RAND() AND a=1.10e0;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
+Warnings:
+Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where ((`test`.`t1`.`a` = 1.10e0) and (<cache>(length(1.10)) <> rand()))
+DROP TABLE t1;
+CREATE TABLE t1 (a DOUBLE(10,3));
+INSERT INTO t1 VALUES (1.1),(1.2),(1.3);
+SELECT * FROM t1 WHERE LENGTH(a)!=5;
+a
+SELECT * FROM t1 WHERE LENGTH(a)!=5 AND a=1.10e0;
+a
+EXPLAIN EXTENDED
+SELECT * FROM t1 WHERE LENGTH(a)!=5 AND a=1.10e0;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE
+Warnings:
+Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where 0
+# Notice 1.100 rather than 1.10 in the final WHERE condition
+EXPLAIN EXTENDED
+SELECT * FROM t1 WHERE LENGTH(a)!=RAND() AND a=1.10e0;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
+Warnings:
+Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where ((`test`.`t1`.`a` = 1.10e0) and (<cache>(length(1.100)) <> rand()))
+DROP TABLE t1;
+#
+# End of 10.1 tests
+#

mysql-test/t/type_float.test

@@ -385,3 +385,67 @@ DROP TABLE t1,t2;
 --echo #
 --echo # End of 10.0 tests
 --echo #
+
+
+--echo #
+--echo # MDEV-8704 Wrong result for SELECT..WHERE LENGTH(double_column)!=6 AND double_column=100e0
+--echo #
+
+# The original test case from the bug report
+CREATE TABLE t1 (a DOUBLE(9,2));
+INSERT INTO t1 VALUES (100),(110);
+SELECT * FROM t1 WHERE LENGTH(a)!=6;
+SELECT * FROM t1 WHERE LENGTH(a)!=6 AND a=100e0;
+DROP TABLE t1;
+
+# DOUBLE with no specific precision
+CREATE TABLE t1 (a DOUBLE);
+INSERT INTO t1 VALUES (100),(110);
+SELECT * FROM t1 WHERE LENGTH(a)!=6;
+SELECT * FROM t1 WHERE LENGTH(a)!=6 AND a=100e0;
+EXPLAIN EXTENDED
+SELECT * FROM t1 WHERE LENGTH(a)!=6 AND a=100e0;
+EXPLAIN EXTENDED
+SELECT * FROM t1 WHERE LENGTH(a)!=RAND() AND a=100e0;
+DROP TABLE t1;
+
+# The constant scale is bigger than the field scale
+CREATE TABLE t1 (a DOUBLE(10,1));
+INSERT INTO t1 VALUES (1.1),(1.2),(1.3);
+SELECT * FROM t1 WHERE LENGTH(a)!=3;
+SELECT * FROM t1 WHERE LENGTH(a)!=3 AND a=1.10e0;
+EXPLAIN EXTENDED
+SELECT * FROM t1 WHERE LENGTH(a)!=3 AND a=1.10e0;
+--echo # Notice 1.1 instead of 1.10 in the final WHERE condition
+EXPLAIN EXTENDED
+SELECT * FROM t1 WHERE LENGTH(a)!=RAND() AND a=1.10e0;
+DROP TABLE t1;
+
+# The constant scale is equal to the field scale
+CREATE TABLE t1 (a DOUBLE(10,2));
+INSERT INTO t1 VALUES (1.1),(1.2),(1.3);
+SELECT * FROM t1 WHERE LENGTH(a)!=4;
+SELECT * FROM t1 WHERE LENGTH(a)!=4 AND a=1.10e0;
+EXPLAIN EXTENDED
+SELECT * FROM t1 WHERE LENGTH(a)!=4 AND a=1.10e0;
+--echo # Notice 1.10 in the final WHERE condition
+EXPLAIN EXTENDED
+SELECT * FROM t1 WHERE LENGTH(a)!=RAND() AND a=1.10e0;
+DROP TABLE t1;
+
+# The constant scale is smaller than the field scale
+CREATE TABLE t1 (a DOUBLE(10,3));
+INSERT INTO t1 VALUES (1.1),(1.2),(1.3);
+SELECT * FROM t1 WHERE LENGTH(a)!=5;
+SELECT * FROM t1 WHERE LENGTH(a)!=5 AND a=1.10e0;
+EXPLAIN EXTENDED
+SELECT * FROM t1 WHERE LENGTH(a)!=5 AND a=1.10e0;
+--echo # Notice 1.100 rather than 1.10 in the final WHERE condition
+EXPLAIN EXTENDED
+SELECT * FROM t1 WHERE LENGTH(a)!=RAND() AND a=1.10e0;
+DROP TABLE t1;
+
+
+--echo #
+--echo # End of 10.1 tests
+--echo #

sql/field.cc

@@ -4639,6 +4639,28 @@ bool Field_real::get_date(MYSQL_TIME *ltime,ulonglong fuzzydate)
 }
 
 
+Item *Field_real::get_equal_const_item(THD *thd, const Context &ctx,
+                                       Item_field *field_item,
+                                       Item *const_item)
+{
+  if (flags & ZEROFILL_FLAG)
+    return Field_num::get_equal_zerofill_const_item(thd, ctx,
+                                                    field_item, const_item);
+  switch (ctx.subst_constraint()) {
+  case IDENTITY_SUBST:
+    if (const_item->decimal_scale() != Field_real::decimals())
+    {
+      double val= const_item->val_real();
+      return new (thd->mem_root) Item_float(thd, val, Field_real::decimals());
+    }
+    break;
+  case ANY_SUBST:
+    break;
+  }
+  return const_item;
+}
+
+
 String *Field_double::val_str(String *val_buffer,
 			      String *val_ptr __attribute__((unused)))
 {

sql/field.h

@@ -1363,6 +1363,8 @@ class Field_real :public Field_num {
   my_decimal *val_decimal(my_decimal *);
   uint32 max_display_length() { return field_length; }
   uint size_of() const { return sizeof(*this); }
+  Item *get_equal_const_item(THD *thd, const Context &ctx,
+                             Item_field *field_item, Item *const_item);
 };