Informix Error -766

Reasons / Common Causes

-766 fires when an ESQL/C host variable used in an INSERT statement or a WHERE clause isn't null-terminated, on an ANSI-compliant database — per the official guidance, ANSI compliance specifically requires this; the same code might work without null termination on a non-ANSI database.

1. A fixed-length character buffer used as a host variable without a trailing null terminator, per the official guidance — the direct, common cause, especially with char[] buffers that were filled without leaving room for (or setting) the terminator.
2. A string built via non-null-terminating operations (a fixed-width copy that fills the entire buffer with data, with no space left for \0), producing a buffer ESQL/C can't correctly treat as a C string.
3. Code that worked on a non-ANSI database reused against an ANSI-compliant one, surfacing this requirement for the first time.

Solutions / Resolution

1. Ensure every host variable string used in an INSERT or WHERE clause is null-terminated, per the official guidance, on an ANSI-compliant database.
2. Size character buffers to leave room for the null terminator, and explicitly set it after filling the buffer's data:

   char status[11];  /* 10 chars of data + 1 for '\0' */
   strncpy(status, "shipped", sizeof(status) - 1);
   status[sizeof(status) - 1] = '\0';
   

3. Check whether the target database is ANSI-compliant, if this requirement is unexpected:

   SELECT name, is_ansi FROM sysmaster:sysdatabases WHERE name = 'target_db';
   

Examples

A non-null-terminated buffer

char status[10];
memset(status, ' ', 10);
memcpy(status, "shipped", 7);
/* no null terminator anywhere in the 10-byte buffer */
EXEC SQL UPDATE orders SET status = :status WHERE order_id = :order_id;
/* -766, on an ANSI-compliant database */

Corrected

char status[11];
strncpy(status, "shipped", sizeof(status) - 1);
status[sizeof(status) - 1] = '\0';
EXEC SQL UPDATE orders SET status = :status WHERE order_id = :order_id;

Diagnostic Checks

1. Check the target database's ANSI-compliance status.
2. Review the host variable's buffer size and how it's populated, confirming a null terminator is always present within the allocated size.

Related Errors / Related Topics

No closely related error codes are cross-referenced for -766 in this set yet.

ANSI-compliant databases require null-terminated host-variable strings — size buffers with room for \0 and set it explicitly after filling the data.