Update with dynamic tables - sql-server

Question

I have to write update using dynamic sql becaus i know only name of column that I want to update and names of columns which I will use to join tables in my update. But I don't know the numbers of tables and names. Names of tables I will get in parameter of my procedure in this way
declare #Tables = N'Customer,Employee,Owner'
So I want to have update like this:
update t
set [Status] = 100
from
TemporaryTable t
left join Customer t1 on t1.RecordId = t.RecordId
left join Employee t2 on t2.RecordId = t.RecordId
left join Owner t3 on t3.RecordId =t.RecordId
where
t1.RecordId is null
and t2.RecordId is NULL
and t3.RecordId is null
I know that each table will have column RecordId and want to left join this tables to my TemporaryTable on this column but I don't know the names and numbers of tables. For example I will have one, two, or ten tables with different names. I know that this tables names will be save in parameter #Tables in that way:
#Tables = N'Customer,Employee,Owner'
There is possilble to write this update in dynamic way?

Answer 1

This is an answer, which helps ... to write update using dynamic sql ... and only shows how to generate a dynamic statement. It's based on string splitting. From SQL Server 2016+ you may use STRING_SPLIT() (because here the order of the substrings is not important). For previous versions you need to find a string splitting function.
T-SQL:
DECLARE #Tables nvarchar(max) = N'Customer,Employee,Owner'
DECLARE #join nvarchar(max) = N''
DECLARE #where nvarchar(max) = N''
DECLARE #stm nvarchar(max) = N''
SELECT
#join = #join + CONCAT(
N' LEFT JOIN ',
QUOTENAME(s.[value]),
N' t',
ROW_NUMBER() OVER (ORDER BY (SELECT 1)),
N' ON t',
ROW_NUMBER() OVER (ORDER BY (SELECT 1)),
N'.RecordId = t.RecordId'
),
#where = #where + CONCAT(
N' AND t',
ROW_NUMBER() OVER (ORDER BY (SELECT 1)),
N'.RecordId is NULL'
)
FROM STRING_SPLIT(#Tables, N',') s
SET #stm = CONCAT(
N'UPDATE t SET [Status] = 100 ',
N'FROM TemporaryTable t',
#join,
N' WHERE ',
STUFF(#where, 1, 5, N'')
)
PRINT #stm
EXEC sp_executesql #stm
Notes:
One note, that I think is important - consider passing tables names using table value type for parameter, not as comma-separated text.

Answer 2

It seems like this will suit your needs, though I don't fully understand what you're trying to do. Here we're constructing the final SQL in two pieces (#s and #where) and then concatenating into the final SQL at the end.
declare #Tables varchar(100) = N'Customer,Employee,Owner'
declare #tablenames table (tablename nvarchar(100))
insert #tablenames (tablename)
select value
from string_split(#Tables, ',');
declare #where varchar(max) = ''
declare #s varchar(max) = '
update t
set [Status] = 100
from TemporaryTable t'
select #s += '
left join ' + tablename + ' on ' + tablename + '.RecordId = t.RecordId'
, #where += case when #where = '' then '' else ' and ' end + tablename + '.RecordId is null
'
from #tablenames
print #s + char(13) + ' where ' + #where
exec( #s + char(13) + ' where ' + #where)