Скачать или смотреть How to Select Values Within a Specified Range in SQL

Learn how to select records within a specified range in SQL using a simple query. This guide will help you understand how to retrieve data based on minimum and maximum values from your table.
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This video is based on the question https://stackoverflow.com/q/65947492/ asked by the user 'Luis Alberto Gonzalez Diaz' ( https://stackoverflow.com/u/12662673/ ) and on the answer https://stackoverflow.com/a/65947498/ provided by the user 'Gordon Linoff' ( https://stackoverflow.com/u/1144035/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Selecting Values Within a Specified Range in SQL

When working with databases, it's common to need to retrieve records based on certain criteria. One such scenario is selecting values from a table that fall within a specified range. If you've ever faced the challenge of determining which records meet a certain numerical criterion (like identifying which color ranges a particular value belongs to), this guide is for you!

Understanding the Problem

Suppose you have a table named color_indicator with the following structure:

IDMINMAX12.00NULL21.002.003NULL1.00The Issue at Hand

You want to query this table to find the ID for a specific VALUE based on the defined MIN and MAX columns. For example, if you are looking for VALUE = 0.9, the desired output should be ID 3 as this value is within the range defined by the minimum limit of the third record in your table.

The SQL Solution

To achieve this, you can utilize a simple SQL query incorporating conditional logic to handle the NULL values appropriately. Here’s how you can structure the query:

SQL Query

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

Breaking Down the Query

SELECT Statement: SELECT ci.* retrieves all columns from the color_indicator table for the conditions that follow.

Alias: FROM color_indicator ci uses ci as an alias for easier reference to the table.

Conditionals:

(:value >= MIN OR MIN IS NULL): This condition checks if the VALUE is greater than or equal to the MIN value. If the MIN value is NULL, it effectively ignores this condition, thereby allowing any value to qualify in that respect.

(:value <= MAX OR MAX IS NULL): This checks if the VALUE is less than or equal to the MAX value, similarly allowing for flexible conditions when MAX is NULL.

Example Usage

Assuming your testing value is 0.9, you would execute the query like this:

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

This set-up, combined with the query, would return the desired ID, which is 3 in this case.

Conclusion

By employing this structured approach to selecting records within a specified range, you enhance the versatility of your SQL queries. Remember, handling NULL values correctly is crucial in SQL operations to avoid unexpected results. The provided query is a solid template, which can be modified according to your own table structures and requirements.

Now, you can confidently select values from your SQL tables based on ranges. Happy querying!