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ALTER TABLE ALTER COLUMN SET NOT NULL #5456

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168 changes: 74 additions & 94 deletions _includes/v19.2/sql/diagrams/alter_column.html
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2 changes: 1 addition & 1 deletion v19.2/add-constraint.md
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Expand Up @@ -11,7 +11,7 @@ The `ADD CONSTRAINT` [statement](sql-statements.html) is part of `ALTER TABLE` a
- [Foreign key](#add-the-foreign-key-constraint-with-cascade)

{{site.data.alerts.callout_info}}
The [`PRIMARY KEY`](primary-key.html) and [`NOT NULL`](not-null.html) constraints can only be applied through [`CREATE TABLE`](create-table.html). The [`DEFAULT`](default-value.html) constraint is managed through [`ALTER COLUMN`](alter-column.html).
The [`PRIMARY KEY`](primary-key.html) can only be applied through [`CREATE TABLE`](create-table.html). The [`DEFAULT`](default-value.html) and [`NOT NULL`](not-null.html) constraints are managed through [`ALTER COLUMN`](alter-column.html).
{{site.data.alerts.end}}

{% include {{ page.version.version }}/sql/combine-alter-table-commands.md %}
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13 changes: 12 additions & 1 deletion v19.2/alter-column.md
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Expand Up @@ -4,7 +4,9 @@ summary: Use the ALTER COLUMN statement to set, change, or drop a column's DEFAU
toc: true
---

The `ALTER COLUMN` [statement](sql-statements.html) is part of `ALTER TABLE` and sets, changes, or drops a column's [`DEFAULT` constraint](default-value.html) or drops the [`NOT NULL` constraint](not-null.html).
The `ALTER COLUMN` [statement](sql-statements.html) is part of `ALTER TABLE` and can be used to:
- Set, change, or drop a column's [`DEFAULT` constraint](default-value.html)
- Set or drop a column's [`NOT NULL` constraint](not-null.html)

{{site.data.alerts.callout_info}}
To manage other constraints, see [`ADD CONSTRAINT`](add-constraint.html) and [`DROP CONSTRAINT`](drop-constraint.html).
Expand Down Expand Up @@ -56,6 +58,15 @@ If the column has a defined [`DEFAULT` value](default-value.html), you can remov
> ALTER TABLE subscriptions ALTER COLUMN newsletter DROP DEFAULT;
~~~

### Set `NOT NULL` constraint

Setting the [`NOT NULL` constraint](not-null.html) specifies that the column cannot contain `NULL` values.

{% include copy-clipboard.html %}
~~~ sql
> ALTER TABLE subscriptions ALTER COLUMN newsletter SET NOT NULL;
~~~

### Remove `NOT NULL` constraint

If the column has the [`NOT NULL` constraint](not-null.html) applied to it, you can remove the constraint, which means the column becomes optional and can have *NULL* values written into it.
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2 changes: 1 addition & 1 deletion v19.2/alter-table.md
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Expand Up @@ -24,7 +24,7 @@ Subcommand | Description | Can combine with other subcommands?
-----------|-------------|------------------------------------
[`ADD COLUMN`](add-column.html) | Add columns to tables. | Yes
[`ADD CONSTRAINT`](add-constraint.html) | Add constraints to columns. | Yes
[`ALTER COLUMN`](alter-column.html) | Change or drop a column's [`DEFAULT` constraint](default-value.html) or drop the [`NOT NULL` constraint](not-null.html). | Yes
[`ALTER COLUMN`](alter-column.html) | Change or drop a column's [`DEFAULT` constraint](default-value.html) or [`NOT NULL` constraint](not-null.html). | Yes
[`ALTER TYPE`](alter-type.html) | Change a column's [data type](data-types.html). | Yes
[`CONFIGURE ZONE`](configure-zone.html) | [Configure replication zones](configure-replication-zones.html) for a table. | No
[`DROP COLUMN`](drop-column.html) | Remove columns from tables. | Yes
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