Informix Error -759: Cannot use database commands in an explicit database connection.

Reasons / Common Causes

-759 fires when a session connected via CONNECT TO database@server then attempts a database selection statement (like DATABASE) to pick a different database — per the official guidance, once connected this way, changing databases requires disconnecting first, not another selection statement.

1. A session using CONNECT TO database@server syntax, then attempting DATABASE other_database, per the official guidance — the direct, only cause.
2. Code written assuming the implicit-connection DATABASE-switching pattern works the same way after an explicit CONNECT TO, when it doesn't.

Solutions / Resolution

1. Disconnect the current connection before selecting a different database, per the official guidance:

   DISCONNECT CURRENT;
   CONNECT TO other_database@server;
   

2. If multiple databases genuinely need to be accessed concurrently, use separate named connections (via CONNECT TO ... AS connection_name) and SET CONNECTION to switch between them, rather than trying to reselect a database on the same connection.

Examples

The disallowed attempt

CONNECT TO 'stores7@server_a';
DATABASE other_db;
-- -759: can't select another database on an explicit connection

Corrected — disconnect and reconnect

CONNECT TO 'stores7@server_a';
-- ... work done ...
DISCONNECT CURRENT;
CONNECT TO 'other_db@server_a';

Or corrected — separate named connections

CONNECT TO 'stores7@server_a' AS conn1;
CONNECT TO 'other_db@server_a' AS conn2;
SET CONNECTION conn2;

Diagnostic Checks

1. Check whether the session connected via explicit CONNECT TO, and if so, replace any subsequent DATABASE statement with a disconnect/reconnect or a separate named connection.

Related Errors / Related Topics

• -758 — "Cannot implicitly reconnect to the new server server_name." A closely related restriction, about implicitly switching servers rather than databases after an explicit CONNECT TO.

The same explicit-connection pattern as -758 — disconnect and reconnect, or use separate named connections with SET CONNECTION.