Learn the benefits of unique primary keys, basic table creation, and the use of identity and primary key constraints for efficient SQL database management.
Although this is useful when we want to put a unique constraint on a single column, sometimes we may want to add unique constraints on a composite key, which is a combination of columns. To define a composite unique key, we can use table constraints. We’ll discuss that in the next sec...
Thus, ordered indexes cannot be used to handle uniqueness constraints in the general case. An important point for both IndexMemory and DataMemory is that the total database size is the sum of all data memory and all index memory for each node group. Each node group is used to store ...
define a primary key, an index must be created (theprimary index) on the same set of columns, in the same order as those columns. If you are defining referential constraints forDb2to enforce, takes steps to maintain data integrity read before creating or altering any of the tables involved...
Structured Query Language (SQL) is the set of statements with which all programs and users access data in an Oracle database.
Group Level Constraints TMS enforces the following additional constraints for group levels. A level can be linked to a group level or a sublevel within it, but not to both. If two group levels are linked, none of the sublevels can be linked directly to sublevels in the other group. A ...
Current MS documentation of SQL Server's CHECK Constraints gives a nice example of a sort of similar function and the problem that's caused if you try to require row counts to be non-zero (if you don't have any rows there are no rows with counts that are n...
Define Constraints and Indexes as necessary; see "Defining Table Constraints and Indexes" Creating a New Table Definition and Instance When you select Create new table definition and instance in the Create Table screen, additional fields appear. Enter values in the following fields: Name. See "Nami...
They are also used in NDB Cluster to handle uniqueness constraints. Currently, the only partitioning algorithm is hashing and ordered indexes are local to each node. Thus, ordered indexes cannot be used to handle uniqueness constraints in the general case. ...
stored with the ROLAP storage mode. This is different from SQL Server 2000 Analysis Services. When you define a fact dimension, you can define the relationship between the fact dimension and the measure group as a fact relationship. The following constraints apply to fact relationships:...