Informix Error -310: Table table-name already exists in database.

Reasons / Common Causes

-310 is a straightforward uniqueness restriction: only one table with a given name can exist in a single (non-ANSI) database. ANSI-compliant databases relax this slightly — they allow one table per name per user, qualified by the creator's username — but outside that mode, the name has to be unique across the whole database regardless of who creates it.

1. A CREATE TABLE statement using a name that already exists in the target database — the direct, most common cause.
2. Running a setup/migration script more than once without a preceding DROP TABLE IF EXISTS-equivalent check, so the second run collides with the first.
3. Wrong database connected — the table doesn't conflict in the database the developer had in mind, but does in whichever database the session is actually connected to.
4. In an ANSI-compliant database, a different user's table of the same name already exists, and the current attempt isn't being correctly scoped/qualified as expected.

Solutions / Resolution

1. Verify the table name's spelling and confirm it's genuinely intended to be a new, distinct table — per the official guidance.
2. Confirm the session is connected to the correct database before running CREATE TABLE.
3. Query systables to review existing permanent tables in the current database:

   SELECT tabname, owner FROM systables WHERE tabtype = 'T' AND tabname = 'orders';
   

4. For repeatable setup scripts, drop the existing table first (or check for its existence before creating), rather than assuming a clean database on every run.
5. In an ANSI-compliant database, qualify the table name by owner if per-user tables with the same base name are intended.

Examples

Re-running a setup script without a guard

CREATE TABLE orders (
    order_id INTEGER PRIMARY KEY,
    customer_id INTEGER
);
-- Running the same script again later:
CREATE TABLE orders (
    order_id INTEGER PRIMARY KEY,
    customer_id INTEGER
);
-- -310: orders already exists

Fix — check first, or make the script idempotent:

SELECT tabname FROM systables WHERE tabname = 'orders' AND tabtype = 'T';
-- if found, DROP TABLE orders; before recreating,
-- or skip the CREATE TABLE entirely

Confirming the current database before creating

DATABASE sales;
SELECT tabname FROM systables WHERE tabname = 'orders' AND tabtype = 'T';
-- confirm this really is the intended database before CREATE TABLE

Diagnostic Checks

1. Query systables for the table name in question, restricted to tabtype = 'T' (permanent tables), to confirm whether it already exists in this database.
2. Confirm the currently connected database matches the one the script or statement was intended for.

Related Errors / Related Topics

• -296 — "Referenced table table-name not available." Another table-existence-related error, though about a table being missing/unreachable rather than already present.

Query systables first to confirm whether the name is really already taken in this database before assuming a typo or writing a workaround.