Subqueries can be categorized into two types:
- A non-correlated (simple) subquery obtains its results independently of its containing (outer) statement.
- A correlated subquery references values from its outer query in order to execute.
When a non-correlated subquery executes (independently of the outer query), the subquery executes first, and then passes its results to the outer query. Meanwhile, a correlated subquery typically obtains values from its outer query before it executes. When the subquery returns, it passes its results to the outer query.
Now that we know the difference between a correlated subquery and its non-correlated counterpart, this blog will cover how to write a correlated subquery in Navicat Premium 16.
As you are no doubt aware, updating text values in the database is a commonplace occurrence. Nonetheless, it is a rare database administrator (DBA) that doesn't feel some trepidation upon executing batch updates against production tables. In today's blog, we'll learn how to use the SQL REPLACE() function to replace either a complete or partial string in a table column.
The Code Snippets feature was introduced to all "Non-Essentials" Navicat Database Administration and Development tools in version 12. Version 16 added Code Snippets to Navicat's cloud services so that users could save their Code Snippets to the cloud and share them across Navicat products. For those of you who are unfamiliar with the Code Snippets feature, it allows you to insert reusable code into your SQL statements when working in the SQL Editor. Besides gaining access to a collection of built-in snippets, you can also define your own snippets. We've talked about Code Snippets before. The March 14, 2018 blog, Using Navicat Code Snippets, provided a general overview of the Code Snippets feature. Today's blog will cover how to create your own custom Code Snippets. It's something that can make writing queries a whole lot easier!
Aliases temporarily rename a table or a column in such a way that does not affect the underlying table(s) or view(s). As a feature of SQL that is supported by most, if not all, relational database management systems, aliases are a great way to both simplify your queries and/or customize the column headers in your result sets. In this blog, we'll do both, using Navicat Premium 16.
Tablespace Management
This 3rd and final part of the Navicat 16 and Tablespaces series will focus on how to manage tablespaces in MySQL using Navicat Premium 16. Recall that Part 1 presented some advantages offered by tablespaces, including Recoverability, Ease of Adding More Tables, Automatic Storage Management, and the Ability to Isolate Data in Buffer Pools for Improved Performance or Memory Utilization. The second installment provided more information on what tablespaces are, how they work and the types of default tablespaces you'll find in the various relational database products.
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