Understanding the Limitations of SQL BETWEEN Operator

The SQL BETWEEN operator is often used to filter data within a specific range. However, its usage can sometimes lead to unexpected results when combined with other operators like OR. In this article, we will explore how to use BETWEEN and OR together in SQL queries to achieve the desired outcome.

Background on SQL BETWEEN Operator

The BETWEEN operator is used to select values within a specified range. It takes two arguments: the lower bound of the range and the upper bound of the range. In SQL, these bounds are inclusive, meaning that both the lower and upper bounds are considered part of the range.

For example, if we use the following query:

SELECT * FROM table WHERE age BETWEEN 20 AND 30;

This will return all rows where the age column is greater than or equal to 20 and less than or equal to 30.

Limitations of SQL BETWEEN Operator

However, when using BETWEEN, there are some limitations we need to be aware of:

• Inclusive bounds: As mentioned earlier, BETWEEN includes both the lower and upper bounds in the range. This means that if you want to exclude the upper bound, you should use a syntax like age > 20 AND age <= 30.
• Null values: The BETWEEN operator is inclusive of null values. For example, if we have a column with some null values and we use age BETWEEN 20 AND 30, all rows with null values in the age column will be included.
• Floating-point numbers: When using floating-point numbers, there can be issues due to rounding errors. This is because SQL uses binary arithmetic for calculations.

Understanding OR Operator

The OR operator is used to combine two or more conditions together. It returns true if any of the conditions are met.

In the context of SQL queries, we often use the OR operator to filter data that meets certain criteria. For example:

SELECT * FROM table WHERE type = 'MANUAL' OR type = 'SYSTEM';

This will return all rows where either the type column is equal to 'MANUAL' or equal to 'SYSTEM'.

Combining BETWEEN and OR Operators

Now, let’s talk about how we can combine these two operators together.

When using BETWEEN and OR, we need to be careful because both conditions are being evaluated separately. This means that if the upper bound of the range is also a condition in the OR clause, it will affect the result.

For example, let’s say we want to get all rows where the CAL_DT column falls within a certain date range and also meets one or more specific conditions:

SELECT CAL_DT AS CALDATE,
       SUM(ORDER_PALL) AS PALL,
       SUM(ORDER_QTY) AS UNI
FROM [ORDER]
WHERE CAL_DT BETWEEN '20210807' AND '20210816'
AND TYPE IN ('MANUAL', 'SYSTEM')
GROUP BY CAL_DT
ORDER BY CAL_DT;

In this query, the BETWEEN operator is used to filter rows based on a specific date range. The IN operator is then used with two conditions: 'MANUAL' and 'SYSTEM'.

Solving the Problem

Let’s return to the original problem where we want to use BETWEEN to filter data within a certain date range along with one or more specific conditions:

SELECT CAL_DT AS CALDATE,
       SUM(ORDER_PALL) AS PALL,
       SUM(ORDER_QTY) AS UNI
FROM [ORDER]
WHERE CAL_DT BETWEEN '2021-08-07' AND '2021-08-16'
OR TYPE IN ('MANUAL', 'SYSTEM')
OR GMM IN ('123', '345')
GROUP BY CAL_DT
ORDER BY CAL_DT ASC;

In this query, the BETWEEN operator is used to filter rows based on a specific date range. However, there’s an issue with the OR clause because it also includes conditions that depend on other columns.

To solve this problem, we need to use the correct syntax for combining these operators:

SELECT CAL_DT AS CALDATE,
       SUM(ORDER_PALL) AS PALL,
       SUM(ORDER_QTY) AS UNI
FROM [ORDER]
WHERE (CAL_DT BETWEEN '2021-08-07' AND '2021-08-16')
OR TYPE IN ('MANUAL', 'SYSTEM')
OR GMM IN ('123', '345')
GROUP BY CAL_DT
ORDER BY CAL_DT ASC;

By using parentheses around the BETWEEN operator, we ensure that it is evaluated first and then combined with the rest of the conditions.

Alternative Approach

If you want to use a more alternative approach where both conditions are evaluated together in the same WHERE clause, you can do so by separating them with an AND keyword:

SELECT CAL_DT AS CALDATE,
       SUM(ORDER_PALL) AS PALL,
       SUM(ORDER_QTY) AS UNI
FROM [ORDER]
WHERE CAL_DT BETWEEN '2021-08-07' AND '2021-08-16'
AND (TYPE IN ('MANUAL', 'SYSTEM') OR GMM IN ('123', '345'))
GROUP BY CAL_DT
ORDER BY CAL_DT ASC;

In this query, both conditions are evaluated together using the AND keyword. This way, we avoid some of the potential issues associated with combining these operators.

Conclusion

When working with SQL queries, understanding how to combine different operators like BETWEEN and OR is crucial for effective filtering and data retrieval. By mastering these concepts, you’ll be able to write more efficient and effective queries that meet your specific needs.

Last modified on 2025-01-22