From d50caace5fa82b2281f5118c49f6754609d51ba9 Mon Sep 17 00:00:00 2001
From: unknown <igor@olga.mysql.com>
Date: Sun, 22 Jul 2007 18:26:16 -0700
Subject: [PATCH] Fixed bug #29611. If a primary key is defined over column c
 of enum type then the EXPLAIN command for a look-up query of the form  
 SELECT * FROM t WHERE c=0 said that the query was with an impossible where
 condition though the query correctly returned non-empty result set when the
 table indeed contained rows with error empty strings for column c.

This kind of misbehavior was due to a bug in the function
Field_enum::store(longlong,bool) that erroneously returned 1 if
the the value to be stored was equal to 0.
Note that the method
Field_enum::store(const char *from,uint length,CHARSET_INFO *cs)
correctly returned 0 if a value of the error empty string
was stored.


mysql-test/r/type_enum.result:
  Added a test case for bug #29661.
mysql-test/t/type_enum.test:
  Added a test case for bug #29661.
sql/field.cc:
  Fixed bug #29611.
  If a primary key was defined over column c of enum type then
  the EXPLAIN command for a look-up query of the form
    SELECT * FROM t WHERE c=0
  said that the query was with an impossible where condition though the
  query correctly returned non-empty result set when the table indeed
  contained rows with error empty strings for column c.

  This kind of misbehavior was due to a bug in the function
  Field_enum::store(longlong,bool) that erroneously returned 1 if
  the the value to be stored was equal to 0.
  Note that the method
  Field_enum::store(const char *from,uint length,CHARSET_INFO *cs)
  correctly returned 0 if a value of the error empty string
  was stored.
---
 mysql-test/r/type_enum.result | 24 ++++++++++++++++++++++++
 mysql-test/t/type_enum.test   | 24 ++++++++++++++++++++++++
 sql/field.cc                  |  7 +++++--
 3 files changed, 53 insertions(+), 2 deletions(-)

diff --git a/mysql-test/r/type_enum.result b/mysql-test/r/type_enum.result
index ca516f027ba..994001d94e5 100644
--- a/mysql-test/r/type_enum.result
+++ b/mysql-test/r/type_enum.result
@@ -1829,3 +1829,27 @@ c1 + 0
 0
 2
 DROP TABLE t1,t2;
+CREATE TABLE t1(a enum('a','b','c','d'));
+INSERT INTO t1 VALUES (4),(1),(0),(3);
+Warnings:
+Warning	1265	Data truncated for column 'a' at row 3
+SELECT a FROM t1;
+a
+d
+a
+
+c
+EXPLAIN SELECT a FROM t1 WHERE a=0;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	Using where
+SELECT a FROM t1 WHERE a=0;
+a
+
+ALTER TABLE t1 ADD PRIMARY KEY (a);
+EXPLAIN SELECT a FROM t1 WHERE a=0;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	const	PRIMARY	PRIMARY	1	const	1	Using index
+SELECT a FROM t1 WHERE a=0;
+a
+
+DROP TABLE t1;
diff --git a/mysql-test/t/type_enum.test b/mysql-test/t/type_enum.test
index fbba38f926d..3dedb0018b1 100644
--- a/mysql-test/t/type_enum.test
+++ b/mysql-test/t/type_enum.test
@@ -200,3 +200,27 @@ CREATE TABLE t2 SELECT * FROM t1;
 SELECT c1 + 0 FROM t2;
 
 DROP TABLE t1,t2;
+
+#
+# Bug#29661: Lookup by 0 for a primary index over a enum type  
+#
+
+CREATE TABLE t1(a enum('a','b','c','d'));
+INSERT INTO t1 VALUES (4),(1),(0),(3);
+
+SELECT a FROM t1;
+
+EXPLAIN SELECT a FROM t1 WHERE a=0;
+SELECT a FROM t1 WHERE a=0;
+
+ALTER TABLE t1 ADD PRIMARY KEY (a);
+
+EXPLAIN SELECT a FROM t1 WHERE a=0;
+SELECT a FROM t1 WHERE a=0;
+
+DROP TABLE t1;
+
+
+
+
+
diff --git a/sql/field.cc b/sql/field.cc
index 993c1fb3c4f..4a1320af48c 100644
--- a/sql/field.cc
+++ b/sql/field.cc
@@ -7640,8 +7640,11 @@ int Field_enum::store(longlong nr, bool unsigned_val)
   if ((ulonglong) nr > typelib->count || nr == 0)
   {
     set_warning(MYSQL_ERROR::WARN_LEVEL_WARN, WARN_DATA_TRUNCATED, 1);
-    nr=0;
-    error=1;
+    if (nr != 0 || table->in_use->count_cuted_fields)
+    {
+      nr= 0;
+      error= 1;
+    }
   }
   store_type((ulonglong) (uint) nr);
   return error;