1. Press Windows Key + X key and click on Command Prompt (Admin) from the task list. 2. Right-click Command Prompt from the start search list and then click Run as administrator. Note: If you are prompted for an administrator password or for a confirmation, type the password, or click Allow. 3.
A constraint is anything that prevents the system from achieving its goal. There are many ways that constraints can show up, but a core principle within TOC is that there are not tens or hundreds of constraints. There is at least one but at most only a few in any given system.
Column and Table Constraints. Constraints can be column constraints or table constraints. A column constraint is specified as part of a column definition and applies only to that column. The constraints in the previous examples are column constraints.QL Server supports the following classes of constraints: NOT NULL specifies that the column does not accept NULL values. For more information, see Allowing Null Values. CHECK constraints enforce domain integrity by limiting the values that can be put in a column. For more information, see CHECK Constraints.