Informix Error -390

Reasons / Common Causes

-390 is the synonym-level counterpart of -310: synonyms share the same namespace as table names within a database, so CREATE SYNONYM fails if the chosen name is already in use by either an existing table or another existing synonym.

1. A CREATE SYNONYM statement using a name already assigned to a table — the direct cause.
2. A CREATE SYNONYM statement using a name already assigned to another synonym.
3. Running a setup/migration script more than once without a preceding existence check.
4. Wrong database connected — the name conflicts in the database the session is actually attached to, not the one intended.

Solutions / Resolution

1. Query systables to review existing table names and synonyms, per the official guidance:

   SELECT tabname, owner FROM systables WHERE tabid > 99;
   

   (System catalog tables occupy tabid values 99 and below, so this filters to user objects.)
2. Choose a genuinely available name for the new synonym.
3. For repeatable setup scripts, check for the name's existence first before attempting CREATE SYNONYM.

Examples

Checking existing names before creating a synonym

SELECT tabname, owner FROM systables WHERE tabid > 99;
-- confirm the intended synonym name isn't already a table or
-- synonym in this database

Re-running a setup script safely

SELECT tabname FROM systables WHERE tabname = 'cust' AND tabid > 99;
-- if found, skip CREATE SYNONYM or DROP SYNONYM first
CREATE SYNONYM cust FOR customers;

Diagnostic Checks

1. Query systables for the intended synonym name, filtered to user objects (tabid > 99).
2. Confirm the currently connected database matches the one the script was intended for.

Related Errors / Related Topics

• -310 — "Table table-name already exists in database." The table-level counterpart of this same shared-namespace uniqueness restriction.
• -316 — "Index index-name already exists in database." Another already-exists restriction, in a separate (index) namespace rather than the shared table/synonym one.

Synonyms and table names share one namespace per database — check systables (not just existing synonyms) before choosing a new synonym name.