How to append specific Word to each column using Dynamic Query in SQL Server - sql-server

Question

From a temp table I populate from the sys schema, I want to assemble a Dynamic SQL query that appends the word PriorYear to each column alias.
The pseudocode looks like this:
DECLARE #SQLSTR nvarchar(max);
SET #SQLSTR = 'SELECT'
FOR EACH TABLEITEM IN #temptbllist
FOR EACH COLUMNITEM IN #tempschema WHERE table_name = TABLEITEM
SET #SQLSTR COLUMNITEM ' as PriorYear' + COLUMNITEM
ENDFOR
SET #SQLSTR 'FROM ' + TABLEITEM ';'
ENDFOR
Starting with this DDL:
CREATE TABLE #tempschema
(
schema_name VARCHAR(30) NOT NULL,
table_name VARCHAR(30) NOT NULL,
column_name VARCHAR(30) NOT NULL,
)
INSERT INTO #tempschema
VALUES
( 'TestSchema', 'Employee', 'ID'),
( 'TestSchema', 'Employee', 'FirstName'),
( 'TestSchema', 'Employee', 'LastName'),
( 'TestSchema', 'Employee', 'Rank'),
( 'TestSchema', 'Employee', 'Salary'),
( 'TestSchema', 'Facility', 'ID'),
( 'TestSchema', 'Facility', 'FacilityName'),
( 'TestSchema', 'Facility', 'County'),
( 'TestSchema', 'Facility', 'State'),
( 'TestSchema', 'Facility', 'ZipCode'),
( 'TestSchema', 'Manager', 'EmployeeID'),
( 'TestSchema', 'Manager', 'Department'),
( 'TestSchema', 'Manager', 'YearStarted');
CREATE TABLE #temptbllist
(
tblname VARCHAR(30) NOT NULL
)
INSERT INTO #temptbllist
VALUES
('Facility');
Thanks in advance

Answer 1

You can just use two nested STRING_AGG aggregations.
I strongly suggest you also use QUOTENAME to quote the columns and tables correctly.
DECLARE #SQLSTR nvarchar(max);
SELECT #SQLSTR =
STRING_AGG(
CONCAT(
'SELECT
',
ts.columns,
'
FROM ',
QUOTENAME(ts.schema_name),
'.',
QUOTENAME(ts.table_name),
';'
),
'
' )
FROM #temptbllist tt
CROSS APPLY (
SELECT
ts.schema_name,
ts.table_name,
columns = STRING_AGG(CAST(QUOTENAME(ts.column_name) + N' as ' + QUOTENAME(N'PriorYear' + ts.column_name) AS nvarchar(max)), ', ')
FROM #tempschema ts
WHERE ts.table_name = tt.tblname
GROUP BY
ts.schema_name,
ts.table_name
) ts;
db<>fiddle