SQL中的BETWEEN操作符用於篩選指定範(fàn)圍內(nèi)的數(shù)據(jù)，且包含邊界值。其基本語(yǔ)法為：SELECT column_name FROM table_name WHERE column_name BETWEEN value1 AND value2；其中value1和value2定義範(fàn)圍，順序需從小到大排列，否則可能無(wú)結(jié)果；它適用於數(shù)字、日期和字符串等數(shù)據(jù)類型，但字符串比較受數(shù)據(jù)庫(kù)排序規(guī)則影響；常見(jiàn)錯(cuò)誤包括誤用順序、非範(fàn)圍型數(shù)據(jù)或忘記其包含邊界值的特性；此外，NOT BETWEEN可用於篩選範(fàn)圍外的數(shù)據(jù)；使用時(shí)應(yīng)注意數(shù)據(jù)類型的兼容性和值的順序以避免問(wèn)題。

The BETWEEN operator in SQL is a handy tool for filtering data within a specific range. It's commonly used in WHERE clauses to select values that fall between two endpoints — and it includes both the start and end values in the result.

How Does BETWEEN Work?

The basic syntax looks like this:

 SELECT column_name
FROM table_name
WHERE column_name BETWEEN value1 AND value2;

Here's what you need to know:

• value1 and value2 define the range.
• The order matters: BETWEEN 'A' AND 'Z' works, but BETWEEN 'Z' AND 'A' usually won't return anything unless your database handles ranges differently (which most don't by default).
• It's inclusive — so both value1 and value2 are included in the results.

For example, if you want to find all employees with salaries from 50,000 to 80,000:

 SELECT name
FROM employees
WHERE salary BETWEEN 50000 AND 80000;

This query will return anyone whose salary is 50,000 , 80,000 , or anything in between.

What Can You Use BETWEEN With?

You're not limited to numbers. BETWEEN works well with several data types:

• Numbers : Perfect for checking numeric ranges.
• Dates : Handy when filtering records between two dates.
• Strings : Works alphabetically, which can be useful but sometimes tricky.

Here's a date example:

 SELECT order_id
FROM orders
WHERE order_date BETWEEN '2023-01-01' AND '2023-12-31';

That would get all orders placed during 2023.

With strings, it depends on your database's collat??ion settings, but generally:

 SELECT product_name
FROM products
WHERE product_name BETWEEN 'Apple' AND 'Banana';

Would include any product names starting with "Apple" up through "Banana" — like "Applesauce", "Apricot", and "Banana Split".

Common Mistakes and Tips

Here are some things people often trip over:

• Forgetting that BETWEEN is inclusive. If you only want one side, use , <code>> , etc., instead.
• Using BETWEEN with inconsistent or non-range data types — stick to comparable values.
• Mixing up the order of values. Always go from lower to higher.

If you're not getting the expected results, double-check:

• Are your values in the right order?
• Is your data type compatible?
• Could there be hidden spaces or case sensitivity affecting string comparisons?

Also, remember that NOT BETWEEN does the opposite — it returns values outside the specified range.

Final Thoughts

Using BETWEEN makes writing queries cleaner and easier when working with ranges. Just keep in mind how it treats boundaries and data types, and you'll avoid most issues.

基本上就這些。

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