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Tag Archives: SQL

Testing Dockerized SQL Databases

One of the big advantages of using Docker for testing is that you don’t need to install the required dependencies of code under tests in all machines where you are going to run these tests. This is really helpful for external services such as database servers, mail services, JMS queues, … Also one of the big advantages of this approach is ...

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SQL Data Access in Play using Scala

Today’s modern application frameworks come with apromise of easy sql data access. There is no wonder why we have so many frameworks that make it easier to issue queries and handle transactions. SQL is the lingua franca of most applications when it comes to databases. Play comes with the JDBC plugin. We encountered the JDBC plugin previously in order to ...

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Creating a SQL Database Project for Isolated Development

Introduction Working with a team of developers often poses challenges and causes frustrations with managing the development database. There are many good approaches to solving the problems of interfering with each others’ code, but my preferred solution has become the SQL Server Database Project in Visual Studio. This article will show you how to take an existing SQL database and ...

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Fixed-Point and Floating-Point: Two Things That Don’t Go Well Together

One of the more challenging aspects of software development can be dealing with floating-point numbers. David Goldberg‘s 1991 Computing Surveys paper What Every Computer Scientist Should Know About Floating-Point Arithmetic is a recognized classic treatise on this subject. This paper not only provides an in-depth look at how floating-point arithmetic is implemented in most programming languages and computer systems, but ...

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Apache Drill SQL Queries on Parquet Data

In this week’s Whiteboard Walkthrough Parth Chandra, Chair of PMC for Apache Drill project and member of MapR engineering team, describes how the Apache Drill SQL query engine reads data in Parquet format and some of the best practices to get maximum performance from Parquet. Additional Apache Drill resources: ”Overview Apache Drill’s Query Execution Capabilities” Whiteboard Walkthrough video “SQL Query ...

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How to remove duplicate rows from a table in SQL

There are a couple of ways to remove duplicate rows from a table in SQL e.g. you can use a temp tables or a window function like row_number() to generate artificial ranking and remove the duplicates. By using a temp table, you can first copy all unique records into a temp table and then delete all data from the original table ...

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SQL Query on Mixed Schema Data Using Apache Drill

You may have heard this statement before:      Apache Drill does schema discovery on-the-fly. What does that mean, and why should it matter to you? The power of SQL for business analytics is a given, but the challenge in big data settings is that SQL is normally a static language that assumes pre-defined, fixed and well-known schema. SQL also needs flat ...

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SQL for Application Developers

“SQL? Isn’t that just something my ORM tools use?” Often application developers can and should remain at least one level removed from SQL. JPA and the Entity Framework each provide more abstract (and OO-friendly) query languages, and it’s often unnecessary to write any queries at all. If you ever diagnose production support issues, though, being proficient with SQL can greatly ...

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