Search results
Results From The WOW.Com Content Network
A column may contain text values, numbers, or even pointers to files in the operating system. [2] Columns typically contain simple types, though some relational database systems allow columns to contain more complex data types, such as whole documents, images, or even video clips. [3] [better source needed] A column can also be called an attribute.
For data requests that fall between the table's samples, an interpolation algorithm can generate reasonable approximations by averaging nearby samples." [8] In data analysis applications, such as image processing, a lookup table (LUT) can be used to transform the input data into a more desirable output format. For example, a grayscale picture ...
A database index is a data structure that improves the speed of data retrieval operations on a database table at the cost of additional writes and storage space to maintain the index data structure. Indexes are used to quickly locate data without having to search every row in a database table every time said table is accessed.
Each column in an SQL table declares the type(s) that column may contain. ANSI SQL includes the following data types. [14] Character strings and national character strings. CHARACTER(n) (or CHAR(n)): fixed-width n-character string, padded with spaces as needed; CHARACTER VARYING(n) (or VARCHAR(n)): variable-width string with a maximum size of n ...
SQL allows triggers to fire on updates to specific columns; As of version 9.0 of PostgreSQL this feature is also implemented in PostgreSQL. The standard allows the execution of a number of SQL statements other than SELECT, INSERT, UPDATE, such as CREATE TABLE as the triggered action. This can be done through creating a stored procedure or ...
The Microsoft xls file format which is the default file format used in versions prior to 2007 had a capacity limit of 65,536 rows by 256 columns (2 16 and 2 8 respectively). [71] This presents a problem for people using larger datasets, and can result in data loss.
Using a unique combination of elements from the original SQL INSERT in a subsequent SELECT statement. Using a GUID in the SQL INSERT statement and retrieving it in a SELECT statement. Using the OUTPUT clause in the SQL INSERT statement for MS-SQL Server 2005 and MS-SQL Server 2008. Using an INSERT statement with RETURNING clause for Oracle.
They give a static snapshot of the data and may include data from remote sources. The accuracy of a materialized view depends on the frequency of trigger mechanisms behind its updates. Materialized views were introduced by Oracle Database , while IBM Db2 provides so-called "materialized query tables" (MQTs) for the same purpose.