Added via ALTER TABLE ... ADD CONSTRAINT name CHECK (expr), this Delta rule requires a deterministic Boolean expression to be true for each row. Current rows are validated before it takes effect, and writes that would break it fail.
Read more: Microsoft Learn
In the Ultra Transcenders books
Each book explains CHECK constraint in context, with comparison tables and the common traps.
Terms in this definition
- Event
Table in Log Analytics where entries from Windows event logs are kept.
- Architecture Definition Document
A key deliverable bringing together the main architecture artifacts across the four domains for every relevant state: baseline, transition and target. It sets out, in qualitative terms, what the architect intends.
Related terms
- ISJSON
Checks a string and returns whether its contents are valid JSON. A CHECK constraint of the form CHECK (ISJSON(col) = 1) uses it to keep nvarchar columns free of malformed JSON.
- JSON_PATH_EXISTS
Returns 1 when a given SQL/JSON path is present in some JSON and 0 when it isn't. Put inside a CHECK constraint, this T-SQL function can make sure a property is always there.