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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 )
Recursive CTEs can be used to traverse relations (as graphs or trees) although the syntax is much more involved because there are no automatic pseudo-columns created (like LEVEL below); if these are desired, they have to be created in the code. See MSDN documentation [2] or IBM documentation [13] [14] for tutorial examples.
In the examples below each trigger is modifying a different table, by looking at what is being modified you can see some common applications of when different trigger types are used. The following is an Oracle syntax example of a row level trigger that is called AFTER an update FOR EACH ROW affected.
Partitioning options on a table in MySQL in the environment of the Adminer tool. A partition is a division of a logical database or its constituent elements into distinct independent parts. Database partitioning refers to intentionally breaking a large database into smaller ones for scalability purposes, distinct from network partitions which ...
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 ...
Max table size Max row size Max columns per row Max Blob/Clob size Max CHAR size Max NUMBER size Min DATE value Max DATE value Max column name size Informix Dynamic Server: ≈0.5 YB 12: ≈0,5YB 12: 32,765 bytes (exclusive of large objects) 32,765 4 TB 32,765 14: 10 125 13: 01/01/0001 10: 12/31/9999 128 bytes Ingres: Unlimited Unlimited 256 KB ...
To process this statement without an index the database software must look at the last_name column on every row in the table (this is known as a full table scan). With an index the database simply follows the index data structure (typically a B-tree ) until the Smith entry has been found; this is much less computationally expensive than a full ...
In a database, a table is a collection of related data organized in table format; consisting of columns and rows. In relational databases , and flat file databases , a table is a set of data elements (values) using a model of vertical columns (identifiable by name) and horizontal rows , the cell being the unit where a row and column intersect ...