Mastering Ecto Queries: Proper Syntax for ilike with SQL Concatenation

Learn how to properly execute Ecto queries using `ilike` and SQL concatenation for name searches in Elixir. Discover effective solutions to common problems in query construction.
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Mastering Ecto Queries: Proper Syntax for ilike with SQL Concatenation

If you're working with Elixir's Ecto library and need to perform queries that involve searching for concatenated values, such as combining first and last names, you might run into some syntax issues. A common challenge arises when trying to use the ilike function along with SQL concatenation to perform case-insensitive searches. In this guide, we will explore how to devise a proper query syntax to achieve the desired functionality.

The Problem

You want to execute an Ecto query that searches for names starting with a specific string—say “Bob J”—by concatenating the first_name and last_name fields. However, your initial attempt with the following code:

[[See Video to Reveal this Text or Code Snippet]]

results in an empty query set. Although an alternative query using wildcards works, you need to adjust your first approach to get it functioning correctly.

The Solution: Constructing the Proper Ecto Query

To successfully concatenate and perform a search with ilike, you can modify your query syntax. Here are two main approaches to achieve this:

Approach 1: Using String Concatenation in PostgreSQL

In this approach, we utilize PostgreSQL's string concatenation capabilities to merge the values of first_name and last_name. Here's how:

Define Your Query String:
Make sure to include wildcard characters to accommodate partial matching.

[[See Video to Reveal this Text or Code Snippet]]

Write the Ecto Query:
Use the fragment function to concatenate the names directly within the SQL query.

[[See Video to Reveal this Text or Code Snippet]]

Approach 2: Using PostgreSQL's CONCAT Function

If you prefer using the CONCAT() function, which explicitly states your intention to concatenate the names, you can do so like this:

Define Your Search Query: Just like before, ensure your query is set up correctly.

[[See Video to Reveal this Text or Code Snippet]]

Modify the Ecto Query:
Here, you will be using the CONCAT() function to achieve the same result.

[[See Video to Reveal this Text or Code Snippet]]

Important Considerations

Spaces Between Concatenated Values:
Neither approach includes a space between first_name and last_name. If you need a space for readability, you could adjust your CONCAT() to include it explicitly:

[[See Video to Reveal this Text or Code Snippet]]

Wildcard Placement:
Make sure to properly structure your wildcard characters when constructing the search query, as shown.

Conclusion

By restructuring your Ecto queries to utilize PostgreSQL's built-in string concatenation functions, you can effectively perform searches with ilike. Whether you choose to use || or the CONCAT() function, both strategies are valid and can enhance your querying flexibility in Elixir applications.

Now you're ready to implement these techniques in your own codebase. Happy querying!

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