How to Upgrade Prerequisite software Ms SQL server using Wix - wix

Question

My application Requires MS SQL Server as one of its Prerequisite.Now i want to upgrade the client machine to MS SQL Server 2008 R2 express edition if they have MS SQL Server 2005 express edition. i am unable to implement it. below is the Wix code i am using for downloading and installing MS SQL server 2008 R2 express edition when no SQL server is installed on client machine.
<?xml version="1.0" encoding="UTF-8"?>
<Wix xmlns="http://schemas.microsoft.com/wix/2006/wi"
xmlns:util="http://schemas.microsoft.com/wix/UtilExtension">
<Fragment>
<util:RegistrySearch Root="HKLM"
Key="SOFTWARE\Microsoft\Microsoft SQL Server\MyInstanceName"
Variable="Instance"
Result="exists"
/>
<PackageGroup Id="SqlServer2008R2">
<ExePackage InstallCommand='/q /action=INSTALL /HIDECONSOLE /IACCEPTSQLSERVERLICENSETERMS=1 /FEATURES=SQLEngine /INSTANCENAME=MyInstanceName /SQLSVCACCOUNT="NT AUTHORITY\SYSTEM" /SECURITYMODE=SQL /SAPWD=abc#Wd1234 /ADDCURRENTUSERASSQLADMIN=TRUE /SQLSYSADMINACCOUNTS="NT AUTHORITY\SYSTEM" /TCPENABLED=1 /NPENABLED=1'
InstallCondition="NOT VersionNT64"
DetectCondition="Instance"
Compressed="no"
Vital="yes"
PerMachine="yes"
Name="SQLEXPR32_x86_ENU.exe"
Permanent="yes"
Cache="no"
DownloadUrl="http://download.microsoft.com/download/5/1/A/51A153F6-6B08- 4F94-A7B2-BA1AD482BC75/SQLEXPR32_x86_ENU.exe"
>
<RemotePayload
Size="60995936"
ProductName="Microsoft SQL Server 2008 R2 Express"
Description="Microsoft SQL Server 2008 R2 Express"
Version="10.50.1600.1"
CertificatePublicKey="672605E36DD71EC6B8325B91C5FE6971390CB6B6"
CertificateThumbprint="9617094A1CFB59AE7C1F7DFDB6739E4E7C40508F"
Hash="ACF5494D18EDF117A2683D66A96FB8954F98D86D"
/>
</ExePackage>
</PackageGroup>
</Fragment>
</Wix>

Answer 1

You cannot use the /action=INSTALL parameter for upgrading an instance only installing a new one. You will have to create another ExePackage with the /action=UPGRADE and setup the InstallCondition to choose the correct one based on the registry searches you do:
<ExePackage Id="SqlExpress2008R2_UpgradeNamedInstance"
Cache="no"
Compressed="no"
PerMachine="yes"
Permanent="no"
Vital="yes"
InstallCommand="/QS /ACTION=Upgrade /IACCEPTSQLSERVERLICENSETERMS /BROWSERSVCSTARTUPTYPE=Automatic /INSTANCENAME="[SqlInstance]""
Name="redist\SQLEXPR_x86_ENU.exe"
DownloadUrl="http://download.microsoft.com/download/D/1/8/D1869DEC-2638-4854-81B7-0F37455F35EA/SQLEXPR_x86_ENU.exe"
InstallCondition="SqlInstance AND SqlServerInstalled AND NOT SQLServer2008R2Installed">
<RemotePayload ProductName="SQL Server 2008 R2 Express SP1"
Description="SQL Server 2008 R2 Express SP1"
CertificatePublicKey="5C499B10F7EF186DC729991A262AB52066423909"
CertificateThumbprint="93859EBF98AFDEB488CCFA263899640E81BC49F1"
Hash="6F399D641F322A3E47E3DD605F2A2EDF21074375"
Size="111274848"
Version="10.50.2500.0" />
</ExePackage>