Check Dialog - pgAdmin 4 4.3 documentation
Use the Check dialog to define or modify a check constraint. A check constraint specifies an expression that produces a Boolean result that new or updated rows must satisfy for an insert or update operation to succeed.
The Check dialog organizes the development of a check constraint through the General and Definition tabs. The SQL tab displays the SQL code generated by dialog selections.
![Check dialog general tab](images/check_general.png)
Use the fields in the General tab to identify the check constraint:
- Use the Name field to provide a descriptive name for the check constraint that will be displayed in the pgAdmin tree control. With PostgreSQL 9.5 forward, when a table has multiple check constraints, they will be tested for each row in alphabetical order by name and after NOT NULL constraints.
- Store notes about the check constraint in the Comment field.
Click the Definition tab to continue.
![Check dialog definition tab](images/check_definition.png)
Use the fields in the Definition tab to define the check constraint:
- Provide the expression that a row must satisfy in the Check field.
- Move the No Inherit? switch to the Yes position to specify this constraint is automatically inherited by a table’s children. The default is No .
- Move the Don’t validate? switch to the No position to skip validation of existing data; the constraint may not hold for all rows in the table. The default is Yes .
Click the SQL tab to continue.
Your entries in the Check dialog generate a SQL command (see an example below). Use the SQL tab for review; revisit or switch tabs to make any changes to the SQL command.
Example
The following is an example of the sql command generated by user selections in the Check dialog:
![Check dialog sql tab](images/check_sql.png)
The example shown demonstrates creating a check constraint named check_price on the price column of the products table. The constraint confirms that any values added to the column are greater than 0.
- Click the Info button (i) to access online help. View context-sensitive help in the Tabbed browser , where a new tab displays the PostgreSQL core documentation.
- Click the Save button to save work.
- Click the Cancel button to exit without saving work.
- Click the Reset button to restore configuration parameters.