SQL Server: Alternative for using Exec in Functions - sql

Question

I am trying to create a Function that I could call to check which is the next ID in key of each table in my database. I figure out how to do it, but I can not create the function because I get this error:
"Invalid use of a side-effecting operator 'INSERT EXEC' within a function."
It seems that I can not use Exec in Functions. Which alternatives could I have to get this information?
This is my code:
CREATE FUNCTION FCN_ProximoID()
RETURNS #TablaID Table (Tabla nvarchar(370), ID int)
AS
BEGIN
-- Fill the table variable with the rows for your result set
DECLARE #Row INT
DECLARE #Filas INT
DECLARE #MaxID INT
DECLARE #Query As varchar(max)
DECLARE #TableName nvarchar(256), #ColumnName nvarchar(128)
SET #Filas = (SELECT MAX(Fila)
FROM (
SELECT ROW_NUMBER() OVER(ORDER BY A.TABLE_NAME) AS 'Fila',
A.TABLE_NAME As Tabla, A.COLUMN_NAME As Columna,
A.ORDINAL_POSITION As Indice, B.DATA_TYPE As TipoDato
FROM
INFORMATION_SCHEMA.KEY_COLUMN_USAGE A
LEFT JOIN INFORMATION_SCHEMA.COLUMNS B
ON A.COLUMN_NAME = B.COLUMN_NAME AND A.TABLE_NAME=B.TABLE_NAME
WHERE LEFT(A.TABLE_NAME,3)='EXT' AND OBJECTPROPERTY(OBJECT_ID
(constraint_name), 'IsPrimaryKey')=1 AND B.DATA_TYPE='int'
) As Tablas)
SET #Row = 1
WHILE (#Row <= #Filas)
BEGIN
BEGIN
SET #TableName = (SELECT Tabla
FROM (
SELECT ROW_NUMBER() OVER(ORDER BY A.TABLE_NAME) AS 'Fila',
A.TABLE_NAME As Tabla, A.COLUMN_NAME As Columna,
A.ORDINAL_POSITION As Indice, B.DATA_TYPE As TipoDato
FROM
INFORMATION_SCHEMA.KEY_COLUMN_USAGE A
LEFT JOIN INFORMATION_SCHEMA.COLUMNS B
ON A.COLUMN_NAME = B.COLUMN_NAME AND
A.TABLE_NAME=B.TABLE_NAME
WHERE LEFT(A.TABLE_NAME,3)='EXT' AND OBJECTPROPERTY(OBJECT_ID
(constraint_name), 'IsPrimaryKey')=1 AND B.DATA_TYPE='int'
) As Tablas WHERE Fila=#Row)
SET #ColumnName = (SELECT Columna
FROM (
SELECT ROW_NUMBER() OVER(ORDER BY A.TABLE_NAME) AS 'Fila',
A.TABLE_NAME As Tabla, A.COLUMN_NAME As Columna,
A.ORDINAL_POSITION As Indice, B.DATA_TYPE As TipoDato
FROM
INFORMATION_SCHEMA.KEY_COLUMN_USAGE A
LEFT JOIN INFORMATION_SCHEMA.COLUMNS B
ON A.COLUMN_NAME = B.COLUMN_NAME AND
A.TABLE_NAME=B.TABLE_NAME
WHERE LEFT(A.TABLE_NAME,3)='EXT' AND
OBJECTPROPERTY(OBJECT_ID
(constraint_name), 'IsPrimaryKey')=1
AND B.DATA_TYPE='int'
) As Tablas WHERE Fila=#Row)
INSERT INTO #TablaID
EXEC('SELECT ''' + #TableName + ''', ISNULL(MAX(' + #ColumnName + '),0)+1 FROM ' + #TableName )
SET #Row = #Row + 1
END
END
RETURN
END
GO

Answer 1

Exec is not allowed in functions, but it is allowed in stored procedures, so you can just rewrite the function as a stored procedure which retuns a resultset.