Category Archives: JDOQL

JDO Typesafe Queries : Part 2 – Expressions

Continuing on from the previous post, in order to be able to express components of a query in a Java style we need to represent all fields/properties/parameters/variables as expressions. The type of the field/property/parameter/variable determines its expression type. Let’s take … Continue reading

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JDO Typesafe Refactorable Queries

One of the primary drawbacks with current JDO queries is that they are string-based, so you are hardcoding field names etc. When you refactor a (model) class, the field names are left unchanged, so the query no longer works. Some … Continue reading

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JDOQL2 status

Some time ago I started a new implementation of JDOQL for RDBMS, to replace the legacy (TJDO) JDOQL implementation. The legacy implementation had problems with generation of SQL for many queries, particularly involving “contains”, “!contains” and use of unbound variables. … Continue reading

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As mentioned earlier DataNucleus querying capabilities are being progressively rewritten, making use of a “generic” query compilation. In the previous post I mentioned a new implementation of JDOQL. This now implements the vast majority of querying capabilities required with one … Continue reading

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DataNucleus started out as JPOX, which started as TJDO. This had support for RDBMS, and in particular JDOQL querying. Unfortunately the TJDO process for JDOQL was a sequential parse of the query string, generating the SQL for the query. While … Continue reading

Posted in DataNucleus, JDO, JDOQL, Persistence | 2 Comments