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  2. Log trigger - Wikipedia

    en.wikipedia.org/wiki/Log_trigger

    OriginalTable REFERENCING NEW AS N OLD AS O FOR EACH ROW MODE DB2SQL BEGIN DECLARE Now TIMESTAMP; SET NOW = CURRENT TIMESTAMP; UPDATE Database. HistoryTable SET EndDate = Now WHERE Column1 = O. Column1 AND EndDate IS NULL; INSERT INTO Database. HistoryTable (Column1, Column2,..., Columnn, StartDate, EndDate) VALUES (N. Column1, N. Column2 ...

  3. Insert (SQL) - Wikipedia

    en.wikipedia.org/wiki/Insert_(SQL)

    For example, in Microsoft SQL Server, the key is retrieved via the SCOPE_IDENTITY() special function, while in SQLite the function is named last_insert_rowid(). Using a database-specific SELECT statement on a temporary table containing last inserted row(s). Db2 implements this feature in the following way:

  4. Database trigger - Wikipedia

    en.wikipedia.org/wiki/Database_trigger

    Before Insert; The four main types of triggers are: Row-level trigger: This gets executed before or after any column value of a row changes. Column-level trigger: This gets executed before or after the specified column changes. For each row type: This trigger gets executed once for each row of the result set affected by an insert/update/delete.

  5. Isolation (database systems) - Wikipedia

    en.wikipedia.org/wiki/Isolation_(database_systems)

    A phantom read occurs when a transaction retrieves a set of rows twice and new rows are inserted into or removed from that set by another transaction that is committed in between. In this example, transaction 1 retrieves the set of rows with age greater than 17, then transaction 2 inserts a row with age 26 and is committed, and finally ...

  6. Data control language - Wikipedia

    en.wikipedia.org/wiki/Data_Control_Language

    Data Control Language is one of the logical group in SQL Commands. SQL [1] is the standard language for relational database management systems. SQL statements are used to perform tasks such as insert data to a database, delete or update data in a database, or retrieve data from a database.

  7. Change data capture - Wikipedia

    en.wikipedia.org/wiki/Change_data_capture

    Change data capture both increases in complexity and reduces in value if the source system saves metadata changes when the data itself is not modified. For example, some Data models track the user who last looked at but did not change the data in the same structure as the data. This results in noise in the Change Data Capture.

  8. Nested set model - Wikipedia

    en.wikipedia.org/wiki/Nested_set_model

    The nested set model is a technique for representing nested set collections (also known as trees or hierarchies) in relational databases. It is based on Nested Intervals, that "are immune to hierarchy reorganization problem, and allow answering ancestor path hierarchical queries algorithmically — without accessing the stored hierarchy relation".

  9. SQL syntax - Wikipedia

    en.wikipedia.org/wiki/SQL_syntax

    The syntax of the SQL programming language is defined and maintained by ISO/IEC SC 32 as part of ISO/IEC 9075.This standard is not freely available. Despite the existence of the standard, SQL code is not completely portable among different database systems without adjustments.