(n.) In a DBMS, a trigger is a SQL procedure that initiates an action (i.e., fires an action) when an event (INSERT, DELETE or UPDATE) occurs. Since triggers are event-driven specialized procedures, they are stored in and managed by the DBMS. A trigger cannot be called or executed; the DBMS automatically fires the trigger as a result of a data modification to the associated table. Triggers are used to maintain the referential integrity of data by changing the data in a systematic fashion.
Each trigger is attached to a single, specified table in the database.
Triggers can be viewed as similar to stored procedures in that both consist of procedural logic that is stored at the database level. Stored procedures, however, are not event-drive and are not attached to a specific table as triggers are. Stored procedures are explicitly executed by invoking a CALL to the procedure while triggers are implicitly executed. In addition, triggers can also execute stored procedures.
A trigger can also contain INSERT, UPDATE and DELETE logic within itself, so when the trigger is fired because of data modification it can also cause another data modification, thereby firing another trigger. A trigger that contains data modification logic within itself is called a nested trigger.
(v.) To initiate an action.
(trub´&l-shoot´´) (v.) To isolate the source of a problem and fix it, typically through a process of elimination whereby possible sources of the problem are investigated and eliminated beginning with the most obvious or easiest problem to fix. Usage Note: In the case of computer systems, the term troubleshoot is usually used when the problem […]
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- true color
Refers to any graphics device or software that uses at least 24 bits to represent each dot or pixel. Using 24 bits means that more than 16 million unique colors can be represented. Since humans can only distinguish a few million colors, this is more than enough to accurately represent any color image.
(v.) To cut off the end of something. Usually, the term is used to describe a type of rounding of floating-point numbers. For example, if there are too few spaces for a long floating-point number, a program may truncate the number by lopping off the decimal digits that do not fit: 3.14126 might be truncated […]
A communications channel between two points. It usually refers to large-bandwidth telephone channels between switching centers that handle many simultaneous voice and data signals. A circuit from a user’s terminal or PC to a network is more accurately called a line (i.e. T1 line or ISDN line) rather than a trunk, although the terms line, […]