T-SQL to learn

xml data type,
xml variable.nodes
xml element.value
select from xmlv.nodes

set showplan_xml on

for xml path(), type
severity level
alter table switch
create index where
outer apply
permission set on assembly

with xmltable
generate xml
openxml
raiseerror with no wait
select fast 50
dm_db_missing_index_details
msdb.sysmail_faileditems