Category: Introduction and Concepts

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Isolation Levels

DB2 provides support for three levels of multiple user concurrency control. These isolation levels select the extent to which database operations performed by one user are isolated from concurrent operations performed by other users. “Repeatable Read” isolation level means that locks are held on all rows read or updated by a user for the duration…
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The JDBC Connectivity to SQL Database Servers

Zim can manipulate and retrieve data from third-party data sources as well as from a Zim database. Client applications for SQL database servers are designed and developed as complete Zim application systems. The objective of the Zim product is 100 percent source code portability of applications including seamless access to databases being managed by SQL…
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Portability Benefits of Zim Client-Server

A Zim Client-Server application can be developed as a stand-alone standard Zim application on any supported platform. Once developed, the application can be moved easily to another platform and configured to access remote data sources. Because of this capability, Zim enables you to separate your application from the ultimate data source, enabling development to be…
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Establishing the SQL Database

If the Zim application being developed is based on an existing SQL database, then the Zim definition interface needs to be executed in order to import the definitions of the relevant tables from the SQL server and populate the Zim data dictionary so that the application can be developed. Conversely, if the Zim application has…
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Transactions

Zim supports two types of transactions: implicit and explicit. An implicit transaction is associated with each individual Zim command that accesses the database in some manner (either read/only or read/write). When the command ends, all locks that were acquired are released and any database updates are committed to the database. If the command fails (e.g.…
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Zim Applications and SQL Database Servers

In Client-Server applications, you do not have to do anything special to access or manipulate data stored in the SQL database. The data definitions of objects under Zim’s control and the data definitions of objects not under Zim’s control are exactly the same. To an application, Zim manipulates both in exactly the same way. The…
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Distributing Data Between Zim and the SQL Database

When developing client-server database applications, it is important to consider the location of the data. Any data under the control of the database server contributes to both the load on the network as well as load on the server machine. Because of this, it is important to analyze the data associated with a given application…
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