2026-02-23
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2026-02-23
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Enforcing Acyclic Hierarchies With SQL Assertions

Introduction Referential integrity constraints have been available since version 7 of the Oracle Database. While these constraints ensure that referenced rows exist, they cannot express more complex integrity rules that span multiple rows or tables. Check constraints are similarly limited, as they can only validate conditions on the columns of a single […]
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2025-01-28
Avoid Implicit Type Conversion in JSON Access
2025-01-28
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Avoid Implicit Type Conversion in JSON Access

Introduction Before comparing two values, the Oracle Database automatically ensures that both values have the same data type. It converts one of the values to match the data type of the other value. The SQL Language Reference manual describes when and how implicit data conversions happen. However, Oracle recommends that you convert […]
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2024-12-24
Evolution of a SQL Domain for Semantic Versioning
2024-12-24
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Evolution of a SQL Domain for Semantic Versioning

1. Introduction In my current project, I use a SQL domain to implement the formatting and precedence rules for Semantic Versioning. I started with a simple implementation covering only the most basic rules. Getting the sorting right is key in my project. It allows me to identify the latest compatible version of […]
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2024-10-16
PL/SQL vs. JavaScrit in the Oracle Database 23ai
2024-10-16
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PL/SQL vs. JavaScript in the Oracle Database 23ai #JoelKallmanDay

JavaScript is the first language supported by the Multilingual Engine (MLE) in Oracle Database 23ai. Having additional languages in the Oracle Database allows us to use existing libraries within the database. Also, it makes it easier for those without PL/SQL skills to get started with database development. Wasn’t that also the argument […]
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2024-09-30
Cartoon-style kiss emoji
2024-09-30
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How Many Bytes Are in an Emoji?

What Is a Byte? A byte is made up of 8 bits. And in the old days, it represented a character. If you use a single-byte character set such as WE8MSWIN1252, WE8ISO8859P15 or similar, it still is. What Is a Character? We can find definitions for example on Wikipedia and in the […]
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2024-07-29
IslandSQL Final Episode 10: Parsing PL/pgSQL
2024-07-29
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IslandSQL Final Episode 10: Parsing PL/pgSQL

Introduction IslandSQL is a parser for SQL files targeting OracleDB or PostgreSQL. The parser is available on Maven Central and can process SQL*Plus, SQLcl or psql statements besides SQL statements. However, the focus is on statements with static DML statements and code in PL/SQL and PL/pgSQL. For static code analysis, for example. […]
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2024-06-27
IslandSQL Episode 9: GraphQL, JSON and Flexible Schemas With Duality Views
2024-06-27
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IslandSQL Episode 9: GraphQL, JSON and Flexible Schemas With Duality Views

Introduction In the last episode, we looked at some new features in Oracle Database 23.4. The IslandSQL grammar now covers all statements that can contain static DML statements and code in PL/SQL and PL/pgSQL. While implementing the ANTLR grammar for the create JSON relational duality view statement I stumbled over GraphQL in […]
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2024-06-15
IslandSQL Episode 8: What's New in Oracle Database 23.4?
2024-06-15
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IslandSQL Episode 8: What’s New in Oracle Database 23.4?

Introduction In the last episode, we looked at some features in PostgreSQL which I miss in the Oracle Database. The IslandSQL grammar now covers PL/SQL and the related DDL statements. The implementation was more complex than expected, mainly because of the incompatibilities between PostgreSQL and the Oracle Database. I will probably deal […]
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2024-03-23
IslandSQL Episode 7: DML Statements in PostgreSQL 16 and What I Miss in Oracle Database 23c
2024-03-23
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IslandSQL Episode 7: DML Statements in PostgreSQL 16 and What I Miss in Oracle Database 23c

Introduction In the last episode, we covered DML statements in SQL*Plus/SQLcl scripts for the Oracle Database 23c. The IslandSQL grammar can now also handle PostgreSQL 16 DML statements in psql scripts. In this blog post, we will look at some features in PostgreSQL 16 which I miss in the Oracle Database 23c. […]
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2024-01-30
IslandSQL Episode 6 - DML Statements in Oracle Database 23c
2024-01-30
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IslandSQL Episode 6: DML Statements in Oracle Database 23c

Introduction The IslandSQL grammar now covers all DML statements. This means call, delete, explain plan, insert, lock table, merge, select and update. In this episode, we will focus on new features in the Oracle Database 23c that can be used in insert, update, delete and merge statements. For the select statement see […]
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