To Update records in table based on values in multiple tables. The query is as follows.
Update T1
set T1.Column1=@Column1
From Table T1
INNER JOIN Table T2 on T1.pkID=T2.fkID
where T2.Column2='somevalue'
To Insert record into table based on values evaluated from different table
insert into T1(column1,column2,column3)
select T1.column1,T2.column2,T3.column3
From table1 T1
inner join Table T2 on T1.pkID=T2.fkID
inner join Table T3 on T1.pkID=T3.fkID
