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The Log Trigger works writing the changes (INSERT, UPDATE and DELETE operations) on the table in another, history table, defined as following: CREATE TABLE HistoryTable ( Column1 Type1 , Column2 Type2 , : : Columnn Typen , StartDate DATETIME , EndDate DATETIME )
Now let's say we have a trigger that uses AFTER instead. The code within the trigger is executed after the INSERT happens to the table. An example use of this trigger is creating an audit history of who has made inserts into the database, keeping track of the changes made. When using these options you need to keep a few things in mind.
For example, LAST_INSERT_ID() for MySQL. 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.
Title Authors ----- ----- SQL Examples and Guide 4 The Joy of SQL 1 An Introduction to SQL 2 Pitfalls of SQL 1 Under the precondition that isbn is the only common column name of the two tables and that a column named title only exists in the Book table, one could re-write the query above in the following form:
Major DBMSs, including SQLite, [5] MySQL, [6] Oracle, [7] IBM Db2, [8] Microsoft SQL Server [9] and PostgreSQL [10] support prepared statements. Prepared statements are normally executed through a non-SQL binary protocol for efficiency and protection from SQL injection, but with some DBMSs such as MySQL prepared statements are also available using a SQL syntax for debugging purposes.
SQL was initially developed at IBM by Donald D. Chamberlin and Raymond F. Boyce after learning about the relational model from Edgar F. Codd [12] in the early 1970s. [13] This version, initially called SEQUEL (Structured English Query Language), was designed to manipulate and retrieve data stored in IBM's original quasirelational database management system, System R, which a group at IBM San ...
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]
MySQL (/ ˌ m aɪ ˌ ɛ s ˌ k juː ˈ ɛ l /) [5] is an open-source relational database management system (RDBMS). [5] [6] Its name is a combination of "My", the name of co-founder Michael Widenius's daughter My, [7] and "SQL", the acronym for Structured Query Language.