When a check is a cross

The brief names a thing you have not given a table, or your table's name is too far from it (the checker accepts singular, plural and common synonyms).

Add the table, or rename yours to the noun the brief uses.

No column is marked key. Every row needs an address so other rows can point at it.

Add an id column and tick key. The builder does this for every new table; you removed it.

The link exists in the brief but not in your tables. The many side needs a column holding the other table's key.

On the many side, add a column named the other table singular plus _id, tick points to, and pick the table.

You ticked points to but left the dropdown on "which table?", or picked the wrong one.

Open the dropdown under the column and pick the table the brief names. If it is not in the list, that table has no name yet.

The column is there, with the right name, but it is a plain column. A name alone does not make a link.

Tick points to on it and pick the table.

The one side carries a pointer to its many side: a pet_id on owners. One cell cannot hold many pets.

Remove that column. The many side already carries the link.

The table is there but has no pointer to the other side.

Same as "has no pointer to": add the column on the many side, tick points to, pick the table.

The brief says exactly one row per parent (one summary per post). A plain pointer allows many.

Tick unique on the pointer column. A second row for the same parent is then refused.

The one column the brief is about (quantity, grade, start date, status) is not on the table where it belongs.

Re-read the brief's last line. The column describes exactly that row, usually the pairing row.

Rename or remove the duplicate. Pointers cannot tell twins apart.

The dropdown is still on "which table?", or the table it pointed at was deleted or renamed.

Pick the table again.

A suggestion, shown with a dot. It never blocks done.

Add it if the brief's product would need it. Otherwise ignore.

The lab saves in this browser on this device. A private window, another browser, cleared site data or another device starts empty.

Use the same browser. Take your screenshots as you go.

Write at least a few words in the box above it. It opens as soon as there is an answer.

Section 5 only draws what you placed. A dashed table or column is one you have not tagged, placed or linked yet.

Click "place it" on the dashed piece; it takes you to the section that places it.

One CSV per table, with two sample rows. Open them in Google Sheets or Excel to see your model as sheets.

"Start again" on a builder resets only that brief. "Reset the whole lab" at the bottom of section 7 wipes everything on this device, including checkpoints.