How to Use LIKE and Wildcard Operators to Filter Data in SQL

Bottom Line (_)

The underscore (_) is a wildcard symbol in SQL that is used to match only one character. In contrast to the percent sign (%), which can match zero or more characters, the underscore only matches one character at a given position in the search pattern. This is especially useful when we want to search for a value with a specific format, but don’t know a single character of that value.

By using the underline, the search becomes more specific and directed, especially if we know there is a variation of the character in a particular place in the value being sought.

Here’s an example query that uses an underscore to search for products with a specific name format:

SELECT prod_id, prod_name
FROM products
WHERE prod_name LIKE '_ ton anvil';

In this query, the search pattern ‘_ton anvil’ indicates that we want to find all products that have a single character before “ton anvil”. The result of this query will include products such as “1 ton anvil” and “2 ton anvil”, as both names have one character before “ton anvil”.

Result Analysis

After the query is executed, the results will display rows from the products table where the prod_name columns match the search pattern. In this example, only products with a single character in front of the “ton anvil” will be displayed. Products like “.5 ton anvil” will not be selected because they have two characters before “ton anvil”.

The use of the underscore as a wildcard makes it easier to search for data in a more targeted way. By understanding how the bottom line works, SQL users can perform more effective searches as per their needs.

Other Interesting Articles

Tips for Effective Use of Wildcards

Wildcards in SQL are very useful for flexible searches. However, to keep the search fast and efficient, there are a few things to keep in mind:

1. Don’t Use Wildcards at the Beginning of the Search:

Using a wildcard at the beginning of a search (e.g., %anvil) can slow down a search. The database must check all the values in the column to find a match, resulting in poor performance. It’s a good idea to place the wildcard at the end or in the middle of the search pattern if possible.

2. Pay Attention to the Wildcard Position:

The position of the wildcard is very important to get the right result. If the wildcard is not placed correctly, the results may not be as expected. For example, if you search for a product with a name that contains “ton” but puts a wildcard before the word, the results may not include all relevant products.

Latest Articles

Related Articles