![]() ![]() ![]() Step 1, install the NPM package called sqlite3 (Read the sqlite3 docs If you find yourself in this situation, this post is about how I was able to complete this challenge safely and on time. Required to use to get my SQLite database up and running had precisely 195,369 lines of SQL code! I needed to get those queries to the DB and the best way would be programmatically, but how? Even if you are not using SQLite, you might still find the technique I used here helpful (you can just skip the SQLite specific parts). In the previous example, you have seen how the subquery was used with the IN operator.In this post, I will show how I was able to get my NodeJS app to run my SQL queries from a SQL file using sqlite3 and NodeJS’ fs APIs. SQL subquery with the IN or NOT IN operator Let’s take some examples of using the subqueries to understand how they work. ![]() You can use a subquery in many places such as: To execute the query, first, the database system has to execute the subquery and substitute the subquery between the parentheses with its result – a number of department id located at the location 1700 – and then executes the outer query. The query that contains the subquery is called an outer query or an outer select. It is also known as an inner query or inner select. The query placed within the parentheses is called a subquery. In this example, you can rewrite combine the two queries above as follows: In this tutorial, we are focusing on the subquery used with the SELECT statement. By definition, a subquery is a query nested inside another query such as SELECT, INSERT, UPDATE, or DELETE statement. However, in the real system with high volume data, it might be problematic.Īnother problem was that you have to revise the queries whenever you want to find employees who locate in a different location.Ī much better solution to this problem is to use a subquery. ![]() However, the original question was not referring to any specific departments it referred to the location 1700.īecause of the small data volume, you can get a list of department easily. To start with, you have looked at the departments table to check which department belongs to the location 1700. ORDER BY first_name, last_name Code language: SQL (Structured Query Language) ( sql ) ![]()
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