How Does Oracle SQL Handle NULL Values in String Concatenation?

Oracle SQL String Connection

Oracle SQL uses || as the string concatenation operator to concatenate two or more strings. How to use is very simple:

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

Potential Problems

It should be noted that there is a special behavior when concatenating with null values:

<code class="language-sql">'x' || null</code>

Unlike other operations, when one of the operands is null, string concatenation does not return a null value, but returns 'x'. If not handled carefully, this can lead to unexpected results.

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