Question

I have to do a big update script – not an SPL (stored procedure).
It’s to be written for an Informix db.

It involves inserting rows into multiple tables, each of which relies on the serial of the insert into the previous table.

I know I can get access to the serial by doing this:

SELECT DISTINCT dbinfo('sqlca.sqlerrd1') FROM systables

but I can’t seem to define a local variable to store this before the insert into the next table.

I want to do this:

insert into table1 (serial, data1, data2) values (0, 'newdata1', 'newdata2');
define serial1 as int;
let serial1 = SELECT DISTINCT dbinfo('sqlca.sqlerrd1') FROM systables;
insert into table2 (serial, data1, data2) values (0, serial1, 'newdata3');

But of course Informix chokes on the define line.

Is there a way to do this without having to create this as a stored procedure, run it once and then delete the procedure?

Answer 1

If the number of columns in the tables involved is as few as your example, then you could make the SPL permanent, and use it to insert your data, ie:

EXECUTE PROCEDURE insert_related_tables('newdata1','newdata2','newdata3');

Obviously that doesn’t scale terribly well, but is OK for your example.

Another thought that expands on Jonathan’s example and solves any concurrency issues that might arise from the use of MAX() would be to include DBINFO('sessionid') in Table3:

DELETE FROM Table3 WHERE sessionid = DBINFO('sessionid');
INSERT INTO Table1 (...);
INSERT INTO Table3 (sessionid, value)
  VALUES (DBINFO('sessionid'), DBINFO('sqlca.sqlerrd1'));
INSERT INTO Table2 
  VALUES (0, (SELECT value FROM Table3
              WHERE sessionid = DBINFO('sessionid'), 'newdata3');
...

You could also make Table3 a TEMP table:

INSERT INTO Table1 (...);
SELECT DISTINCT DBINFO('sqlca.sqlerrd1') AS serial_value
  FROM some_dummy_table_like_systables
INTO TEMP Table3 WITH NO LOG;
INSERT INTO Table2 (...);