Informix Error -676

-676 Invalid check constraint column.

A check constraint that is specified at the column level can reference only that column. To specify a check constraint that spans more than one column, specify the check constraint at the table level. You cannot create a check constraint for columns across tables.

Oninit® Troubleshooting Guidance

Reasons / Common Causes

-676 fires when a column-level CHECK constraint's expression references a column other than the one it's attached to — per the official guidance, a column-level check can only reference that same column; anything spanning multiple columns needs to be a table-level constraint instead.

A column-level CHECK referencing a different column, per the official guidance — the direct, only cause.
A check genuinely needing to compare two columns, written at the column level out of habit rather than being moved to the table level where multi-column checks belong.
A check attempting to reference a column in a different table, per the official guidance's closing note — this isn't supported at either the column or table level; cross-table constraints need a trigger instead.

Solutions / Resolution

Move a multi-column check to the table level, per the official guidance, rather than attaching it to a single column:
```
CREATE TABLE orders (
  order_date DATE,
  ship_date DATE,
  CHECK (ship_date >= order_date)
);
```
For a genuinely single-column check, confirm the expression only references that column.
For a check that would need to span tables, use a trigger instead, per the official guidance — check constraints (column- or table-level) can't reference another table at all.

Examples

The disallowed column-level cross-reference

CREATE TABLE orders (
  order_date DATE CHECK (ship_date >= order_date),
  ship_date DATE
);
-- -676: order_date's column-level check references ship_date

Corrected — a table-level check

CREATE TABLE orders (
  order_date DATE,
  ship_date DATE,
  CHECK (ship_date >= order_date)
);

Diagnostic Checks

Check whether a column-level CHECK's expression references only that column, and move it to the table level if it needs to reference others.

Related Errors / Related Topics

-677 — "Check constraint cannot contain subqueries or procedures." A related CHECK restriction, about what kinds of expressions are allowed regardless of column vs. table level.
-678 — "Invalid subscript for column column-name in check constraint." A related CHECK restriction, about subscript bounds rather than column scope.

Column-level checks can only reference their own column — move a multi-column check to the table level.