why can I only install MySQL 5.1 on cent OS 6.2?
You asked this similar question before about getting MySQL 5.5 and I answered it : I am getting an error while trying to download binary for mysql 5.5.11 (Please upvote it if it helped before)

Here is a script I use to get the latest MySQL 5.5 for RHEL6

HOWMANYBITS=64
WHATOS=6
BINARY_VERSION=000
if [ ${HOWMANYBITS} -eq 32 ] ; then BINARY_VERSION=i386   ; fi
if [ ${HOWMANYBITS} -eq 64 ] ; then BINARY_VERSION=x86_64 ; fi
MINOR_RELEASE=22
MYSQL_RELEASE=5.5.${MINOR_RELEASE}
OS_VERSION=000
if [ ${WHATOS} -eq 0 ] ; then OS_VERSION=linux2.6 ; fi
if [ ${WHATOS} -eq 5 ] ; then OS_VERSION=rhel5    ; fi
if [ ${WHATOS} -eq 6 ] ; then OS_VERSION=el6    ; fi
RELEASE_TAG=1
DEVEL__RPM=http://www.mysql.com/get/Downloads/MySQL-5.5/MySQL-devel-${MYSQL_RELEASE}-${RELEASE_TAG}.${OS_VERSION}.${BINARY_VERSION}.rpm/from/http://mysql.mirrors.pair.com/
SHARD2_RPM=http://www.mysql.com/get/Downloads/MySQL-5.5/MySQL-shared-compat-${MYSQL_RELEASE}-${RELEASE_TAG}.${OS_VERSION}.${BINARY_VERSION}.rpm/from/http://mysql.mirrors.pair.com/
SHARED_RPM=http://www.mysql.com/get/Downloads/MySQL-5.5/MySQL-shared-${MYSQL_RELEASE}-${RELEASE_TAG}.${OS_VERSION}.${BINARY_VERSION}.rpm/from/http://mysql.mirrors.pair.com/
CLIENT_RPM=http://www.mysql.com/get/Downloads/MySQL-5.5/MySQL-client-${MYSQL_RELEASE}-${RELEASE_TAG}.${OS_VERSION}.${BINARY_VERSION}.rpm/from/http://mysql.mirrors.pair.com/
SERVER_RPM=http://www.mysql.com/get/Downloads/MySQL-5.5/MySQL-server-${MYSQL_RELEASE}-${RELEASE_TAG}.${OS_VERSION}.${BINARY_VERSION}.rpm/from/http://mysql.mirrors.pair.com/
PERL_LOCATION=ftp://ftp.de.netclusive.de/pub/parallels/Plesk/Expand/2.3.1/packages
PERL_FILE=perl-DBI-1.53-2.fc7.x86_64.rpm
PERL_URL=${PERL_LOCATION}/${PERL_FILE}
cd
rm -rf MySQL5.5_Install
mkdir MySQL5.5_Install
cd MySQL5.5_Install
wget ${PERL_URL}
wget ${DEVEL__RPM}
wget ${SHARD2_RPM}
wget ${SHARED_RPM}
wget ${CLIENT_RPM}
wget ${SERVER_RPM}
ls -l


When you are satisfied with the downloads, then install them:

for RPM in `ls -lSr *.rpm | awk '{print $9}'` ; do rpm -Uvh --force ${RPM} ; done


Give it a Try !!!

I found the problem. For OS6, change i386 to i686 and the download works ...

[redwards@lw-lts-155 MySQL_5.5.22]$ HOWMANYBITS=32
[redwards@lw-lts-155 MySQL_5.5.22]$ WHATOS=6

MYSQL_INSTALL_FOLDER=MySQL_${MYSQL_RELEASE}
OS_VERSION=000
[redwards@lw-lts-155 MySQL_5.5.22]$ BINARY_VERSION=000
[redwards@lw-lts-155 MySQL_5.5.22]$ if [ ${HOWMANYBITS} -eq 32 ] ; then BINARY_VERSION=i686   ; fi
[redwards@lw-lts-155 MySQL_5.5.22]$ if [ ${HOWMANYBITS} -eq 64 ] ; then BINARY_VERSION=x86_64 ; fi
SERVER_RPM=http://www.mysql.com/get/Downloads/MySQL-5.5/MySQL-server-${MYSQL_RELEASE}-${RELEASE_TAG}.${OS_VERSION}.${BINARY_VERSION}.rpm/from/http://mysql.mirrors.pair.com/
[redwards@lw-lts-155 MySQL_5.5.22]$ MINOR_RELEASE=22
[redwards@lw-lts-155 MySQL_5.5.22]$ MYSQL_RELEASE=5.5.${MINOR_RELEASE}
[redwards@lw-lts-155 MySQL_5.5.22]$ MYSQL_INSTALL_FOLDER=MySQL_${MYSQL_RELEASE}
[redwards@lw-lts-155 MySQL_5.5.22]$ OS_VERSION=000
[redwards@lw-lts-155 MySQL_5.5.22]$ if [ ${WHATOS} -eq 0 ] ; then OS_VERSION=linux2.6 ; fi
[redwards@lw-lts-155 MySQL_5.5.22]$ if [ ${WHATOS} -eq 5 ] ; then OS_VERSION=rhel5    ; fi
[redwards@lw-lts-155 MySQL_5.5.22]$ if [ ${WHATOS} -eq 6 ] ; then OS_VERSION=el6    ; fi
[redwards@lw-lts-155 MySQL_5.5.22]$ RELEASE_TAG=1
[redwards@lw-lts-155 MySQL_5.5.22]$ DEVEL__RPM=http://www.mysql.com/get/Downloads/MySQL-5.5/MySQL-devel-${MYSQL_RELEASE}-${RELEASE_TAG}.${OS_VERSION}.${BINARY_VERSION}.rpm/from/http://mysql.mirrors.pair.com/
[redwards@lw-lts-155 MySQL_5.5.22]$ SHARD2_RPM=http://www.mysql.com/get/Downloads/MySQL-5.5/MySQL-shared-compat-${MYSQL_RELEASE}-${RELEASE_TAG}.${OS_VERSION}.${BINARY_VERSION}.rpm/from/http://mysql.mirrors.pair.com/
[redwards@lw-lts-155 MySQL_5.5.22]$ SHARED_RPM=http://www.mysql.com/get/Downloads/MySQL-5.5/MySQL-shared-${MYSQL_RELEASE}-${RELEASE_TAG}.${OS_VERSION}.${BINARY_VERSION}.rpm/from/http://mysql.mirrors.pair.com/
[redwards@lw-lts-155 MySQL_5.5.22]$ CLIENT_RPM=http://www.mysql.com/get/Downloads/MySQL-5.5/MySQL-client-${MYSQL_RELEASE}-${RELEASE_TAG}.${OS_VERSION}.${BINARY_VERSION}.rpm/from/http://mysql.mirrors.pair.com/
[redwards@lw-lts-155 MySQL_5.5.22]$ SERVER_RPM=http://www.mysql.com/get/Downloads/MySQL-5.5/MySQL-server-${MYSQL_RELEASE}-${RELEASE_TAG}.${OS_VERSION}.${BINARY_VERSION}.rpm/from/http://mysql.mirrors.pair.com/
[redwards@lw-lts-155 MySQL_5.5.22]$ PERL_LOCATION=ftp://ftp.de.netclusive.de/pub/parallels/Plesk/Expand/2.3.1/packages
[redwards@lw-lts-155 MySQL_5.5.22]$ PERL_FILE=perl-DBI-1.53-2.fc7.x86_64.rpm
[redwards@lw-lts-155 MySQL_5.5.22]$ PERL_URL=${PERL_LOCATION}/${PERL_FILE}
[redwards@lw-lts-155 MySQL_5.5.22]$ cd
[redwards@lw-lts-155 ~]$ rm -rf ${MYSQL_INSTALL_FOLDER}
[redwards@lw-lts-155 ~]$ mkdir ${MYSQL_INSTALL_FOLDER}
[redwards@lw-lts-155 ~]$ cd ${MYSQL_INSTALL_FOLDER}
[redwards@lw-lts-155 MySQL_5.5.22]$ wget ${PERL_URL}
--2012-04-10 15:40:23--  ftp://ftp.de.netclusive.de/pub/parallels/Plesk/Expand/2.3.1/packages/perl-DBI-1.53-2.fc7.x86_64.rpm
           =&gt; `perl-DBI-1.53-2.fc7.x86_64.rpm'
Resolving ftp.de.netclusive.de... 89.110.128.25
Connecting to ftp.de.netclusive.de|89.110.128.25|:21... connected.
Logging in as anonymous ... Logged in!
==&gt; SYST ... done.    ==&gt; PWD ... done.
==&gt; TYPE I ... done.  ==&gt; CWD /pub/parallels/Plesk/Expand/2.3.1/packages ... done.
==&gt; SIZE perl-DBI-1.53-2.fc7.x86_64.rpm ... 625843
==&gt; PASV ... done.    ==&gt; RETR perl-DBI-1.53-2.fc7.x86_64.rpm ... done.
Length: 625843 (611K)

100%[===================================================================================================================================&gt;] 625,843      702K/s   in 0.9s

2012-04-10 15:40:26 (702 KB/s) - `perl-DBI-1.53-2.fc7.x86_64.rpm' saved [625843]

[redwards@lw-lts-155 MySQL_5.5.22]$ wget ${DEVEL__RPM}
--2012-04-10 15:40:26--  http://www.mysql.com/get/Downloads/MySQL-5.5/MySQL-devel-5.5.22-1.el6.i686.rpm/from/http://mysql.mirrors.pair.com/
Resolving www.mysql.com... 156.151.63.6
Connecting to www.mysql.com|156.151.63.6|:80... connected.
HTTP request sent, awaiting response... 302 Found
Location: http://mysql.mirrors.pair.com/Downloads/MySQL-5.5/MySQL-devel-5.5.22-1.el6.i686.rpm [following]
--2012-04-10 15:40:26--  http://mysql.mirrors.pair.com/Downloads/MySQL-5.5/MySQL-devel-5.5.22-1.el6.i686.rpm
Resolving mysql.mirrors.pair.com... 216.92.2.145
Connecting to mysql.mirrors.pair.com|216.92.2.145|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 4909292 (4.7M) [text/plain]
Saving to: `MySQL-devel-5.5.22-1.el6.i686.rpm'

100%[===================================================================================================================================&gt;] 4,909,292   3.01M/s   in 1.6s

2012-04-10 15:40:29 (3.01 MB/s) - `MySQL-devel-5.5.22-1.el6.i686.rpm' saved [4909292/4909292]

[redwards@lw-lts-155 MySQL_5.5.22]$ wget ${SHARD2_RPM}
--2012-04-10 15:40:29--  http://www.mysql.com/get/Downloads/MySQL-5.5/MySQL-shared-compat-5.5.22-1.el6.i686.rpm/from/http://mysql.mirrors.pair.com/
Resolving www.mysql.com... 156.151.63.6
Connecting to www.mysql.com|156.151.63.6|:80... connected.
HTTP request sent, awaiting response... 404 Not found
2012-04-10 15:40:29 ERROR 404: Not found.

[redwards@lw-lts-155 MySQL_5.5.22]$ wget ${SHARED_RPM}
--2012-04-10 15:40:29--  http://www.mysql.com/get/Downloads/MySQL-5.5/MySQL-shared-5.5.22-1.el6.i686.rpm/from/http://mysql.mirrors.pair.com/
Resolving www.mysql.com... 156.151.63.6
Connecting to www.mysql.com|156.151.63.6|:80... connected.
HTTP request sent, awaiting response... 302 Found
Location: http://mysql.mirrors.pair.com/Downloads/MySQL-5.5/MySQL-shared-5.5.22-1.el6.i686.rpm [following]
--2012-04-10 15:40:29--  http://mysql.mirrors.pair.com/Downloads/MySQL-5.5/MySQL-shared-5.5.22-1.el6.i686.rpm
Resolving mysql.mirrors.pair.com... 216.92.2.145
Connecting to mysql.mirrors.pair.com|216.92.2.145|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 1685312 (1.6M) [text/plain]
Saving to: `MySQL-shared-5.5.22-1.el6.i686.rpm'

100%[===================================================================================================================================&gt;] 1,685,312   2.92M/s   in 0.6s

2012-04-10 15:40:30 (2.92 MB/s) - `MySQL-shared-5.5.22-1.el6.i686.rpm' saved [1685312/1685312]

[redwards@lw-lts-155 MySQL_5.5.22]$ wget ${CLIENT_RPM}
--2012-04-10 15:40:30--  http://www.mysql.com/get/Downloads/MySQL-5.5/MySQL-client-5.5.22-1.el6.i686.rpm/from/http://mysql.mirrors.pair.com/
Resolving www.mysql.com... 156.151.63.6
Connecting to www.mysql.com|156.151.63.6|:80... connected.
HTTP request sent, awaiting response... 302 Found
Location: http://mysql.mirrors.pair.com/Downloads/MySQL-5.5/MySQL-client-5.5.22-1.el6.i686.rpm [following]
--2012-04-10 15:40:31--  http://mysql.mirrors.pair.com/Downloads/MySQL-5.5/MySQL-client-5.5.22-1.el6.i686.rpm
Resolving mysql.mirrors.pair.com... 216.92.2.145
Connecting to mysql.mirrors.pair.com|216.92.2.145|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 14633936 (14M) [text/plain]
Saving to: `MySQL-client-5.5.22-1.el6.i686.rpm'

100%[===================================================================================================================================&gt;] 14,633,936  3.52M/s   in 4.1s

2012-04-10 15:40:38 (3.44 MB/s) - `MySQL-client-5.5.22-1.el6.i686.rpm' saved [14633936/14633936]

[redwards@lw-lts-155 MySQL_5.5.22]$ wget ${SERVER_RPM}
--2012-04-10 15:40:38--  http://www.mysql.com/get/Downloads/MySQL-5.5/MySQL-server-5.5.22-1.el6.i686.rpm/from/http://mysql.mirrors.pair.com/
Resolving www.mysql.com... 156.151.63.6
Connecting to www.mysql.com|156.151.63.6|:80... connected.
HTTP request sent, awaiting response... 302 Found
Location: http://mysql.mirrors.pair.com/Downloads/MySQL-5.5/MySQL-server-5.5.22-1.el6.i686.rpm [following]
--2012-04-10 15:40:39--  http://mysql.mirrors.pair.com/Downloads/MySQL-5.5/MySQL-server-5.5.22-1.el6.i686.rpm
Resolving mysql.mirrors.pair.com... 216.92.2.145
Connecting to mysql.mirrors.pair.com|216.92.2.145|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 40659264 (39M) [text/plain]
Saving to: `MySQL-server-5.5.22-1.el6.i686.rpm'

100%[===================================================================================================================================&gt;] 40,659,264  3.33M/s   in 11s

2012-04-10 15:40:58 (3.54 MB/s) - `MySQL-server-5.5.22-1.el6.i686.rpm' saved [40659264/40659264]

[redwards@lw-lts-155 MySQL_5.5.22]$ ls -l
total 61140
-rw-r--r-- 1 redwards users 14633936 Mar 13 19:55 MySQL-client-5.5.22-1.el6.i686.rpm
-rw-r--r-- 1 redwards users  4909292 Mar 13 19:55 MySQL-devel-5.5.22-1.el6.i686.rpm
-rw-r--r-- 1 redwards users 40659264 Mar 13 19:56 MySQL-server-5.5.22-1.el6.i686.rpm
-rw-r--r-- 1 redwards users  1685312 Mar 13 19:57 MySQL-shared-5.5.22-1.el6.i686.rpm
-rw-r--r-- 1 redwards users   625843 Apr 10 15:40 perl-DBI-1.53-2.fc7.x86_64.rpm
[redwards@lw-lts-155 MySQL_5.5.22]$


Just run this

for RPM in `ls -lSr *.rpm | awk '{print $9}'` ; do rpm -Uvh --force ${RPM} ; done


and you are good to go !!!