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You can undo the operation of removing records by using the ROLLBACK command; DELETE requires a shared table lock; Triggers fire; DELETE can be used in the case of: database link; DELETE returns the number of records deleted; Transaction log - DELETE needs to read records, check constraints, update block, update indexes, and generate redo / undo.
In the Oracle RDBMS environment, redo logs comprise files in a proprietary format which log a history of all changes made to the database. Each redo log file consists of redo records. A redo record, also called a redo entry, holds a group of change vectors, each of which describes or represents a change made to a single block in the database.
In SQL, the TRUNCATE TABLE statement is a data manipulation language (DML) [1] operation that deletes all rows of a table without causing a triggered action. The result of this operation quickly removes all data from a table, typically bypassing a number of integrity enforcing mechanisms.
"Don't repeat yourself" (DRY), also known as "duplication is evil", is a principle of software development aimed at reducing repetition of information which is likely to change, replacing it with abstractions that are less likely to change, or using data normalization which avoids redundancy in the first place.
Some database designers use surrogate keys systematically regardless of the suitability of other candidate keys, while others will use a key already present in the data, if there is one. Some of the alternate names ("system-generated key") describe the way of generating new surrogate values rather than the nature of the surrogate concept.
In computer programming, duplicate code is a sequence of source code that occurs more than once, either within a program or across different programs owned or maintained by the same entity. Duplicate code is generally considered undesirable for a number of reasons. [ 1 ]
It is analogous to the Unix rm command and to the Stratus OpenVOS delete_file and delete_dircommands. [5] DEC RT-11, [6] OS/8, [7] RSX-11, [8] and OpenVMS [9] also provide the delete command which can be contracted to del. AmigaDOS [10] and TSC FLEX [11] provide a delete command as well. The erase command is supported by Tim Paterson's SCP 86 ...
The former allocates the first available descriptor, just like open() behaves; an alternative way to duplicate a file descriptor to an unspecified place is the fcntl system call with F_DUPFD command. The latter places the copy into newfd. If newfd is open, it is closed first.