Concatenating files in Powershell

When working with databases, it’s best practice to create migration scripts to which apply your database changes, rather than using GUI/designer tools which need you to manually apply changes across multiple environments.

I’ve been working with a client where there isn’t a specific migration tool to run all these migration files at the end of project, but they need to be bundled into a single file and attached to the change tracking system.

I keep these files under version control and prefix migration files with M_ and rollback files with R_

In Bash concatenating these files is simple:
cat M_* > ./migration.sql

In Powershell it isn’t too different:
Get-Content M_* | Set-Content .\migration.sql

When dealing with rollback scripts I create the rollback which opposes the migration with the same number which makes the files easy to navigate:


./M_001_AddsTable.sql
./M_002_AddsView.sql
./R_001_AddsTable.sql
./R_002_AddsView.sql

Rollback scripts are slightly more interesting as they need to be run in reverse.

We can also achieve this in Powershell with a minor tweak to our previous command:
Get-Content R_* | Sort-Object -Property Name -Descending | Get-Content | Set-Content .\migration.sql

This will firstly get all our rollback files and then reverses the order, then gets the content of each file and writes it to a single file.

Although I prefer doing these types of tasks with Bash, it’s still quite easy to remember the Powershell commands if you don’t have access to Bash on a Windows system.

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