Search results
Results from the WOW.Com Content Network
The unique index serves two purposes: (i) to enforce entity integrity, since primary key data must be unique across rows and (ii) to quickly search for rows when queried. Since surrogate keys replace a table's identifying attributes—the natural key —and since the identifying attributes are likely to be those queried, then the query ...
Unique constraint. A unique constraint can be defined on columns that allow nulls, in which case rows that include nulls may not actually be unique across the set of columns defined by the constraint. Each table can have multiple unique constraints. On some RDBMS a unique constraint generates a nonclustered index by default.
The non-clustered index tree contains the index keys in sorted order, with the leaf level of the index containing the pointer to the record (page and the row number in the data page in page-organized engines; row offset in file-organized engines). In a non-clustered index, The physical order of the rows is not the same as the index order.
In the relational model of databases, a primary key is a designated attribute that can reliably identify and distinguish between each individual record in a table.The database creator can choose an existing unique attribute or combination of attributes from the table (a natural key) to act as its primary key, or create a new attribute containing a unique ID that exists solely for this purpose ...
Jay-Z is accused in a lawsuit of raping a 13-year-old girl with fellow music mogul Sean “Diddy” Combs. The lawsuit was first filed in October but did not list Jay-Z, whose given name is Shawn ...
In situations where the number of unique values of a column is far less than the number of rows in the table, column-oriented storage allow significant savings in space through data compression. Columnar storage also allows fast execution of range queries (e.g., show all records where a particular column is between X and Y, or less than X.)
WASHINGTON (Reuters) - U.S. private payrolls increased at a moderate pace in November, while annual wages for workers staying in their jobs edged up for the first time in 25 months.
Grooming-wise, they have double, shedding coats – keep the vacuum cleaner handy. 2. Belgian Malinois. Belgian malinois in owner's arms. These smart dogs have another name – the Maligator. They ...