Highly Irregular Highly Irregular - 2 years ago 493
SQL Question

How to do an insert with multiple rows in Informix SQL?

I want to insert multiple rows with a single insert statement.

The following code inserts one row, and works fine:

create temp table mytmptable
(external_id char(10),
int_id integer,
cost_amount decimal(10,2)
) with no log;

insert into mytmptable values
('7662', 232, 297.26);

select * from mytmptable;

I've tried changing the insert to this, but it gives a syntax error:

insert into mytmptable values
('7662', 232, 297.26),
('7662', 232, 297.26);

Is there a way to get it working, or do I need to run many inserts instead?

Answer Source

As you found, you can't use multiple lists of values in a single INSERT statement with Informix.

The simplest solution is to use multiple INSERT statements each with a single list of values.

If you're using an API such as ESQL/C and you are concerned about performance, then you can create an INSERT cursor and use that repeatedly. This saves up the inserts until a buffer is full, or you flush or close the cursor:

$ PREPARE p FROM "INSERT INTO mytmptable VALUES(?, ?, ?)";
$ OPEN c;
while (...there's more data to process...)
    $PUT c USING :v1, :v2, :v3;
$ CLOSE c;

The variables v1, v2, v3 are host variables to hold the string and numbers to be inserted. (You can optionally use $ FLUSH c; in the loop if you wish.) Because this buffers the values, it is pretty efficient. Of course, you could also simply use $ EXECUTE p USING :v1, :v2, :v3; in the loop; that foregoes the per-row preparation of the statement, too.

If you don't mind writing verbose SQL, you can use the UNION technique suggested by Matt Hamilton, but you will need a FROM clause in each SELECT with Informix. You might specify:

  • FROM "informix".systables WHERE tabid = 1, or
  • FROM sysmaster:"informix".sysdual, or
  • use some other technique to ensure that the SELECT has a FROM clause but only generates one row of data.

In my databases, I have either a table dual with a single row in it, or a synonym dual that is a synonym for sysmaster:"informix".sysdual. You can get away without the "informix". part of those statements if the database is 'normal'; the owner name is crucial if your database is an Informix MODE ANSI database.

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