From 0920c75b5efa164253c546f88e30b9b4fe686e6b Mon Sep 17 00:00:00 2001
From: unknown <gshchepa/uchum@gleb.loc>
Date: Thu, 12 Jul 2007 00:03:08 +0500
Subject: [PATCH] Fixed bug #29360. The special `zero' enum value was coerced
 to the normal empty string enum value during a field-to-field copy. This bug
 affected CREATE ... SELECT statements and SELECT aggregate GROUP BY enum
 field statements.

Also this bug made unnecessary warnings during
the execution of CREATE ... SELECT statements:
Warning       1265    Data truncated for column...


sql/field_conv.cc:
  Fixed bug #29360.
  The field_conv function has been modified to properly convert
  the special `zero' enum value between enum fields.
mysql-test/t/type_enum.test:
  Updated test case for bug #29360.
mysql-test/r/type_enum.result:
  Updated test case for bug #29360.
mysql-test/r/type_ranges.result:
  Updated test case for bug #29360.
---
 mysql-test/r/type_enum.result   | 20 ++++++++++++++++++++
 mysql-test/r/type_ranges.result |  4 ----
 mysql-test/t/type_enum.test     | 18 ++++++++++++++++++
 sql/field_conv.cc               | 16 +++++++++++-----
 4 files changed, 49 insertions(+), 9 deletions(-)

diff --git a/mysql-test/r/type_enum.result b/mysql-test/r/type_enum.result
index f537b7140ba..ca516f027ba 100644
--- a/mysql-test/r/type_enum.result
+++ b/mysql-test/r/type_enum.result
@@ -1809,3 +1809,23 @@ f1
 
 
 drop table t1;
+CREATE TABLE t1 (c1 ENUM('a', '', 'b'));
+INSERT INTO t1 (c1) VALUES ('b');
+INSERT INTO t1 (c1) VALUES ('');
+INSERT INTO t1 (c1) VALUES (0);
+Warnings:
+Warning	1265	Data truncated for column 'c1' at row 1
+INSERT INTO t1 (c1) VALUES ('');
+SELECT c1 + 0, COUNT(c1) FROM t1 GROUP BY c1;
+c1 + 0	COUNT(c1)
+0	1
+2	2
+3	1
+CREATE TABLE t2 SELECT * FROM t1;
+SELECT c1 + 0 FROM t2;
+c1 + 0
+3
+2
+0
+2
+DROP TABLE t1,t2;
diff --git a/mysql-test/r/type_ranges.result b/mysql-test/r/type_ranges.result
index e949d734944..5c2d3b84d89 100644
--- a/mysql-test/r/type_ranges.result
+++ b/mysql-test/r/type_ranges.result
@@ -208,10 +208,6 @@ options	flags
 one	one
 drop table t2;
 create table t2 select * from t1;
-Warnings:
-Warning	1265	Data truncated for column 'options' at row 4
-Warning	1265	Data truncated for column 'options' at row 5
-Warning	1265	Data truncated for column 'options' at row 6
 update t2 set string="changed" where auto=16;
 show full columns from t1;
 Field	Type	Collation	Null	Key	Default	Extra	Privileges	Comment
diff --git a/mysql-test/t/type_enum.test b/mysql-test/t/type_enum.test
index ecc945a3157..fbba38f926d 100644
--- a/mysql-test/t/type_enum.test
+++ b/mysql-test/t/type_enum.test
@@ -182,3 +182,21 @@ create table t1(f1 set('a','b'), index(f1));
 insert into t1 values(''),(''),('a'),('b');
 select * from t1 where f1='';
 drop table t1;
+
+#
+# Bug#29360: Confluence of the special 0 enum value with the normal empty string
+# value during field to field copy.
+#
+
+CREATE TABLE t1 (c1 ENUM('a', '', 'b'));
+INSERT INTO t1 (c1) VALUES ('b');
+INSERT INTO t1 (c1) VALUES ('');
+INSERT INTO t1 (c1) VALUES (0);
+INSERT INTO t1 (c1) VALUES ('');
+
+SELECT c1 + 0, COUNT(c1) FROM t1 GROUP BY c1;
+
+CREATE TABLE t2 SELECT * FROM t1;
+SELECT c1 + 0 FROM t2;
+
+DROP TABLE t1,t2;
diff --git a/sql/field_conv.cc b/sql/field_conv.cc
index a286255ec23..2df65b62de6 100644
--- a/sql/field_conv.cc
+++ b/sql/field_conv.cc
@@ -790,11 +790,17 @@ int field_conv(Field *to,Field *from)
       blob->value.copy();
     return blob->store(blob->value.ptr(),blob->value.length(),from->charset());
   }
-  if ((from->result_type() == STRING_RESULT &&
-       (to->result_type() == STRING_RESULT ||
-	(from->real_type() != FIELD_TYPE_ENUM &&
-	 from->real_type() != FIELD_TYPE_SET))) ||
-      to->type() == FIELD_TYPE_DECIMAL)
+  if (from->real_type() == FIELD_TYPE_ENUM &&
+      to->real_type() == FIELD_TYPE_ENUM &&
+      from->val_int() == 0)
+  {
+    ((Field_enum *)(to))->store_type(0);
+  }
+  else if ((from->result_type() == STRING_RESULT &&
+            (to->result_type() == STRING_RESULT ||
+             (from->real_type() != FIELD_TYPE_ENUM &&
+              from->real_type() != FIELD_TYPE_SET))) ||
+           to->type() == FIELD_TYPE_DECIMAL)
   {
     char buff[MAX_FIELD_WIDTH];
     String result(buff,sizeof(buff),from->charset());