How Does Oracle's String Concatenation Operator Handle NULL Values?

String concatenation operator in Oracle

When dealing with strings in Oracle SQL, the string concatenation operator (represented by ||) plays a vital role in concatenating two or more string values.

To perform string concatenation, simply use the || operator between the strings you want to combine. For example:

<code class="language-sql">SELECT 'Mr ' || ename FROM emp;</code>

In this example, the 'Mr ' string is concatenated with the ename column in the emp table, producing a string that starts with "Mr" followed by the employee's name.

While this operator seems simple, there is a significant caveat to note:

• Handling of NULL values: Unlike many other languages, Oracle does not treat NULL values ​​in strings as empty strings. Conversely, 'x' || NULL returns 'x', not NULL.

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