Disable or Enable all SQL Agent Jobs

declare @sql nvarchar(max) = '';
select
@sql += N'exec msdb.dbo.sp_update_job @job_name = ''' + name + N''', @enabled = 0;
' from msdb.dbo.sysjobs
where enabled = 1  --1= Enabled, 0 is disabled
order by name;

print @sql;
--exec (@sql);