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There is also an IGNORE clause for the INSERT statement, [7] which tells the server to ignore "duplicate key" errors and go on (existing rows will not be inserted or updated, but all new rows will be inserted). SQLite's INSERT OR REPLACE INTO works similarly. It also supports REPLACE INTO as an alias for compatibility with MySQL. [8]
Unique rows (no duplicate records) [4] Scalar columns (columns cannot contain relations or composite values) [5] Every non-prime attribute has a full functional dependency on each candidate key (attributes depend on the whole of every key) [5]
Upon successful completion of the decoding, the decoded CDR batches are then checked for duplicate records. Duplicate CDRs are discarded and reported on. The TPS administrators are responsible for verifying the CDRs flagged as duplicates, are in fact true duplicates. [4] Depending on the TPS software used, the processes following the CDR ...
All the candidate keys of a relation can uniquely identify the records of the relation, but only one of them is used as the primary key of the relation. The remaining candidate keys are called unique keys because they can uniquely identify a record in a relation. Unique keys can consist of multiple columns. Unique keys are also called alternate ...
A check constraint is a type of integrity constraint in SQL which specifies a requirement that must be met by each row in a database table. The constraint must be a predicate . It can refer to a single column, or multiple columns of the table.
In computer main memory, auxiliary storage and computer buses, data redundancy is the existence of data that is additional to the actual data and permits correction of errors in stored or transmitted data.
In SQL (Structured Query Language), the term cardinality refers to the uniqueness of data values contained in a particular column (attribute) of a database table.The lower the cardinality, the more duplicated elements in a column.
Begin: Record a timestamp marking the transaction's beginning. Modify: Read database values, and tentatively write changes. Validate: Check whether other transactions have modified data that this transaction has used (read or written). This includes transactions that completed after this transaction's start time, and optionally, transactions ...