# Schema (DDL)

Operations that define the database: tables, columns, constraints, bases and views.

## Operations

- [Create a table: `name`, in `catalog` and `schema` (default: the database's defaults); the definition](https://datanotes.dev/api/operations/create_table/): `POST /datanotes/operations/create_table/`
- [Drop a table. Refused while it has rows unless `mode: "archive"`, which removes the](https://datanotes.dev/api/operations/drop_table/): `POST /datanotes/operations/drop_table/`
- [Add a typed column. Sparse by default (written only on rows that have a value — use for](https://datanotes.dev/api/operations/add_column/): `POST /datanotes/operations/add_column/`
- [Rename a column in metastore.yaml and on every row. Refused if `to_column` is already a column](https://datanotes.dev/api/operations/rename_column/): `POST /datanotes/operations/rename_column/`
- [Remove a column from the schema and every row. Previous values are journaled; revert with](https://datanotes.dev/api/operations/drop_column/): `POST /datanotes/operations/drop_column/`
- [Change a column's attributes (type, min/max/step, values, required, default, label,](https://datanotes.dev/api/operations/alter_column/): `POST /datanotes/operations/alter_column/`
- [Alter a table: move it (`catalog`, `schema`), rename it (`name`), change](https://datanotes.dev/api/operations/alter_table/): `POST /datanotes/operations/alter_table/`
- [Create or replace a base: a named set of columns (same spec as `create_table`) that tables](https://datanotes.dev/api/operations/define_base/): `POST /datanotes/operations/define_base/`
- [Set the bases a table inherits from (`bases`, in order; `[]` removes them). Inherited](https://datanotes.dev/api/operations/set_table_bases/): `POST /datanotes/operations/set_table_bases/`
- [COMMENT ON CATALOG / SCHEMA: set the `description` of a catalog (`catalog` alone) or of one of its](https://datanotes.dev/api/operations/comment_on/): `POST /datanotes/operations/comment_on/`
- [Rename one value of an enum column (e.g. `high` → `very high`) in metastore.yaml and every](https://datanotes.dev/api/operations/rename_value/): `POST /datanotes/operations/rename_value/`
- [ALTER TABLE ADD CONSTRAINT `name` CHECK: `check` is a where filter every row must match,](https://datanotes.dev/api/operations/add_constraint/): `POST /datanotes/operations/add_constraint/`
- [Remove the CHECK constraint `name` from `table`.](https://datanotes.dev/api/operations/drop_constraint/): `POST /datanotes/operations/drop_constraint/`
- [Create (or `replace`) a view: a named select stored in metastore.yaml. Name it with the prefix](https://datanotes.dev/api/operations/create_view/): `POST /datanotes/operations/create_view/`
- [Remove a view from `metastore.yaml` (undo with `undo_migration`).](https://datanotes.dev/api/operations/drop_view/): `POST /datanotes/operations/drop_view/`
- [CREATE TABLE `target` CLONE `source`: same definition plus independent copies of its rows](https://datanotes.dev/api/operations/clone_table/): `POST /datanotes/operations/clone_table/`