The process of ensuring data that is created, modified, and deleted in one database is done the same on one or more associated databases will be the focus of this session. In real life, it is quite an involved issue with many consequential choices to be considered, weighed, and decided upon.

With the growing trend of databases exchanging data with other databases, a developer needs to be well versed in the recognizing the need for a data exchange strategy. Be it a satellite office, a traveling sales staff, or backup servers, there are growing needs for distributed databases exchanging data in a timely and seamless manner. In this session we'll explore data exchange, sometimes referred to as data replication, in 4D v11 SQL which enables you to exchange data on your device with database applications on other devises in number of ways. The feature of focus will be the new functionality in 4D v11.3 SQL, "4D Pass-Through". 4D Pass-Through is the new SQL feature 4D v11 SQL which facilitates 4D to 4D, 4D to 4D Server, and 4D Server to 4D Server communications without the need of an ODBC bridge, such as the 4D v11 SQL ODBC driver.

In this session we'll also explore a new capability not possible in any prior version of 4D. Database Structure Synchronization using the new commands CREATE TABLE, DROP TABLE, and ALTER TABLE. No longer does a developer need to change out a full 4D v11 SQL structure to deploy structure changes. A developer can now write a method that can log into external database, learn the full structure of a database accessing _USER_TABLES, _USER_COLUMNS, and more and make desired structural changes dynamically.

Many of the issues and strategies of data exchange are covered in the excellent tech note written by Simon Wright in 2003, Replicator Library (Part II) (TN 03-19 April 2003). Replicator Library was all about executing synchronization using a product called 4D Open for 4D. The plug-in 4D Open for 4D is not supported in 4D v11 SQL because with the implementation of the SQL engine within 4D, the supported 4D to 4D communications channel is USE EXTERNAL DATABASE.

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