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SQL select is used to retrieve records from a database, as a result, it returns the records requested.
CTE stands for Common Table Expression, and it is a temporary named result set that you can reference within a SQL statement. A CTE is defined within a query and is available only for the duration of that query. It allows you to create a named temporary table that you can reference multiple times within…
In SQL a lot of the times there will be a need to write subqueries that will extract data that you can analyse. But what if you want to use the data as input to another query that can then be used to give you the result you desire? This is is the power of…
SQL group by is one of the most commonly used statements you will come across and it has many different applications. It is a great way to aggregate data, when you are using one of the following in the select statement: (A) Sum (B)Count (C) Average (D) Max (E) Min There are more that can…
When running an sql select query, most likely we may have a need to bring in data from other tables. The reason for this is that tables have a specific purpose for the data they store. One of the most important features of a data architecture is to avoid duplication. This has the impact of…
Following on from from our previous posts on SQL, this post will help to explain how to use wildcards in your query. What would you use a wild card in the first place? When a data analyst dealing with a large dataset, it is most likely that they will not know every piece of data….
Building on how to select all records with SQL , you may want to learn how to get specific columns of data from your table. Using SQLite again , we will now look to select two columns from the table below, namely name and iso_code. The purpose of completing this, is to allow the user…
As part of working as a data analyst, in order to retrieve your data you will most likely need to connect into a database, and look at the database records and then start analysing, but how? At the start of any data analytics project you will need to understand the structure of your data and…