Informix Error -678

-678 Invalid subscript for column column-name in check constraint.

A subscripted column in a check constraint has subscripts outside the bounds of the column. Check that the bounds specified in the subscripted column do not exceed the maximum length of the column. If you know the table name of the column, use the following subquery to query the system-catalog tables to find out the maximum length of the column:

SELECT collength FROM syscolumns WHERE colname = 'column-name' AND tabid = (SELECT tabid FROM systables WHERE tabname = 'table-name')

Oninit® Troubleshooting Guidance

Reasons / Common Causes

-678 fires when a CHECK constraint's expression subscripts a column with bounds outside the column's actual maximum length — the CHECK-constraint-specific analog of -607's subscript bounds rule.

A subscript's upper bound exceeding the column's declared length, per the official guidance — the direct, only cause.
A CHECK expression written before the column's length was finalized, left unchanged after the column's declared length was later reduced.

Solutions / Resolution

Check that the subscript bounds don't exceed the column's maximum length, per the official guidance.

Look up the column's actual maximum length, per the official guidance's documented query:

SELECT collength FROM syscolumns
WHERE colname = 'column-name'
  AND tabid = (SELECT tabid FROM systables WHERE tabname = 'table-name');

Adjust the subscript bounds in the CHECK expression to fit within that length.

Examples

Exceeding the column's length

CREATE TABLE documents (title VARCHAR(50), CHECK (title[1,100] != ''));
-- -678: 100 exceeds title's declared length of 50

Looking up the actual length, then correcting

SELECT collength FROM syscolumns
WHERE colname = 'title'
  AND tabid = (SELECT tabid FROM systables WHERE tabname = 'documents');
-- returns 50

CREATE TABLE documents (title VARCHAR(50), CHECK (title[1,50] != ''));

Diagnostic Checks

Query syscolumns for the column's collength, per the official guidance's documented query, and compare against the subscript bounds used in the CHECK expression.

Related Errors / Related Topics

-607 — "Text/Byte subscript error." The general subscript-syntax rule this CHECK-specific case is a variant of, for TEXT/BYTE subscripts outside a check-constraint context.
-676 — "Invalid check constraint column." A related CHECK restriction, about column scope rather than subscript bounds.
-677 — "Check constraint cannot contain subqueries or procedures." A related CHECK restriction, about disallowed expression types.

Look up the column's actual collength via syscolumns before setting subscript bounds in a CHECK expression.