From 196528eb42c843ca800b81be27a79c7c4806a057 Mon Sep 17 00:00:00 2001
From: Alexey Botchkov <holyfoot@askmonty.org>
Date: Sun, 14 Jun 2015 18:54:13 +0500
Subject: [PATCH] MDEV-8212 alter table - failing to ADD PRIMARY KEY IF NOT
 EXISTS when existing index of same as column name.         The default name
 for the primary key is rather 'PRIMARY' instead of the indexed column name.

---
 mysql-test/r/alter_table.result | 11 +++++++++++
 mysql-test/t/alter_table.test   |  8 ++++++++
 sql/sql_table.cc                | 17 +++++++++++------
 3 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/mysql-test/r/alter_table.result b/mysql-test/r/alter_table.result
index 4ae7c7aea93..0975a5aa101 100644
--- a/mysql-test/r/alter_table.result
+++ b/mysql-test/r/alter_table.result
@@ -1488,6 +1488,17 @@ t2	CREATE TABLE `t2` (
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 DROP TABLE t2;
 DROP TABLE t1;
+CREATE TABLE t1 (
+`transaction_id` int(11) NOT NULL DEFAULT '0', 
+KEY `transaction_id` (`transaction_id`));
+ALTER TABLE t1 DROP KEY IF EXISTS transaction_id, ADD PRIMARY KEY IF NOT EXISTS (transaction_id);
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `transaction_id` int(11) NOT NULL DEFAULT '0',
+  PRIMARY KEY (`transaction_id`)
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+DROP TABLE t1;
 # Bug#11748057 (formerly known as 34972): ALTER TABLE statement doesn't
 #                                         identify correct column name.
 #
diff --git a/mysql-test/t/alter_table.test b/mysql-test/t/alter_table.test
index 416c73009e6..cbb73bbb3d4 100644
--- a/mysql-test/t/alter_table.test
+++ b/mysql-test/t/alter_table.test
@@ -1326,6 +1326,14 @@ SHOW CREATE TABLE t2;
 DROP TABLE t2;
 DROP TABLE t1;
 
+CREATE TABLE t1 (
+    `transaction_id` int(11) NOT NULL DEFAULT '0', 
+    KEY `transaction_id` (`transaction_id`));
+ALTER TABLE t1 DROP KEY IF EXISTS transaction_id, ADD PRIMARY KEY IF NOT EXISTS (transaction_id);
+SHOW CREATE TABLE t1;
+
+DROP TABLE t1;
+
 --echo # Bug#11748057 (formerly known as 34972): ALTER TABLE statement doesn't
 --echo #                                         identify correct column name.
 --echo #
diff --git a/sql/sql_table.cc b/sql/sql_table.cc
index da2a220d3f1..6ee0e9bc871 100644
--- a/sql/sql_table.cc
+++ b/sql/sql_table.cc
@@ -5859,12 +5859,17 @@ drop_create_field:
       /* let us check the name of the first key part. */
       if ((keyname= key->name.str) == NULL)
       {
-        List_iterator<Key_part_spec> part_it(key->columns);
-        Key_part_spec *kp;
-        if ((kp= part_it++))
-          keyname= kp->field_name.str;
-        if (keyname == NULL)
-          continue;
+        if (key->type == Key::PRIMARY)
+          keyname= primary_key_name;
+        else
+        {
+          List_iterator<Key_part_spec> part_it(key->columns);
+          Key_part_spec *kp;
+          if ((kp= part_it++))
+            keyname= kp->field_name.str;
+          if (keyname == NULL)
+            continue;
+        }
       }
       if (key->type != Key::FOREIGN_KEY)
       {