sql server: Procedure to create sequence - sql-server

Question

I wanna create a stored procedure to check if a sequence is with a given name is exist or no to create it or alter its value to max(Id) selected from given table name, So I create the below procedure but it throws a syntax error.
CREATE PROCEDURE EBPP_CORE.CREATE_OR_ALTER_SEQUENCE
#sequence_name VARCHAR2,
#table_name VARCHAR2
AS
BEGIN
DECLARE #MAX_ID_VAL NUMBER;
DECLARE #sequence_exist NUMBER;
SELECT #MAX_ID_VAL = CAST(ISNULL(MAX(id) + 1, 1) as nvarchar(10)) FROM #table_name ;
SELECT #sequence_exist = COUNT(*) FROM sys.sequences WHERE name = #sequence_name;
IF #sequence_exist>0
' ALTER SEQUENCE #sequence_name RESTART WITH #MAX_ID_VAL';
ELSE
'CREATE SEQUENCE #sequence_name START WITH #MAX_ID_VAL INCREMENT BY 1' ;
END

Answer 1

You have to use dynamic SQL to both find the current max ID and to create or alter the SEQUENCE objects. Something like this:
CREATE OR ALTER PROCEDURE EBPP_CORE.CREATE_OR_ALTER_SEQUENCE
#sequence_name nvarchar(128),
#table_name nvarchar(128)
AS
/*
drop table if exists foo
go
create table foo(id int)
exec EBPP_CORE.CREATE_OR_ALTER_SEQUENCE 'foo_seq','foo'
insert into foo(id) values (3)
exec EBPP_CORE.CREATE_OR_ALTER_SEQUENCE 'foo_seq','foo'
*/
BEGIN
DECLARE #MAX_ID_VAL bigint;
DECLARE #sequence_exist bigint;
declare #sql nvarchar(max) = concat('select #MAX_ID_VAL = MAX(id) + 1 FROM ', quotename(#table_name));
print #sql;
exec sp_executesql #sql, N'#MAX_ID_VAL bigint output', #MAX_ID_VAL=#MAX_ID_VAL output;
set #MAX_ID_VAL = coalesce(#MAX_ID_VAL,1)
SELECT #sequence_exist = COUNT(*) FROM sys.sequences WHERE name = #sequence_name;
IF #sequence_exist>0
BEGIN
set #sql = concat('ALTER SEQUENCE ', quotename(#sequence_name), ' RESTART WITH ', #MAX_ID_VAL) ;
print #sql;
exec (#sql);
END
ELSE
BEGIN
set #sql = concat('CREATE SEQUENCE ', quotename(#sequence_name), ' START WITH ', #MAX_ID_VAL,' INCREMENT BY 1') ;
print #sql;
exec (#sql);
END
END