Search results
Results from the WOW.Com Content Network
A database dump contains a record of the table structure and/or the data from a database and is usually in the form of a list of SQL statements ("SQL dump"). A database dump is most often used for backing up a database so that its contents can be restored in the event of data loss.
A derived table is the use of referencing an SQL subquery in a FROM clause. Essentially, the derived table is a subquery that can be selected from or joined to. The derived table functionality allows the user to reference the subquery as a table. The derived table is sometimes referred to as an inline view or a subselect.
A table alias is called a correlation name, according to the SQL standard. [1] A programmer can use an alias to temporarily assign another name to a table or column for the duration of the current SELECT query. Assigning an alias does not actually rename the column or table. This is often useful when either tables or their columns have very ...
Although not in standard, most DBMS allows using a select clause without a table by pretending that an imaginary table with one row is used. This is mainly used to perform calculations where a table is not needed. The SELECT clause specifies a list of properties (columns) by name, or the wildcard character (“*”) to mean “all properties”.
In a relational database, the schema defines the tables, fields, relationships, views, indexes, packages, procedures, functions, queues, triggers, types, sequences, materialized views, synonyms, database links, directories, XML schemas, and other elements. A database generally stores its schema in a data dictionary. Although a schema is defined ...
In SQL, the unique keys have a UNIQUE constraint assigned to them in order to prevent duplicates (a duplicate entry is not valid in a unique column). Alternate keys may be used like the primary key when doing a single-table select or when filtering in a where clause, but are not typically used to join multiple tables.
Then a field refers to a single storage location in a specific record (like a cell) to store one value (the field value). The terms record and field come from the more practical field of database usage and traditional DBMS system usage (This was linked into business like terms used in manual databases e.g. filing cabinet storage with records ...
A result set is the set of results returned by a query, usually in the same format as the database the query is called on. [1] For example, in SQL, which is used in conjunction with relational databases, it is the result of a SELECT query on a table or view and is itself a non-permanent table of rows, and could include metadata about the query such as the column names, and the types and sizes ...