Understanding the 8 vs. * Typo in SQL

Understanding the 8 vs. * Typo in SQL: Impact and Interview Insights

When you mistakenly type a literal (like 8) instead of the wildcard *, SQL interprets it as a constant value rather than an instruction to select all columns.

Here's what happens:
SELECT 8 FROM EMPLOYEES;
This query returns a single column where every row contains the value 8.
For example, if there are 107 employees, you’ll get 107 rows with 8 in each row.

Why It Happens:
In SQL, numeric literals (like 8) are treated as constant expressions. The * operator, on the other hand, is a special symbol that tells SQL to return all columns of the table. If you miss the shift key and type 8 instead, SQL doesn’t know you intended a wildcard—it simply sees a constant.

Why It’s an Important Interview Question:
Understanding SQL Syntax: It tests whether you know the specific role of the * operator versus a literal value.

Attention to Detail: It highlights how a simple typing mistake can completely change the outcome of a query.

Concept Clarity: It ensures that you understand how SQL evaluates expressions in the SELECT clause, which is fundamental for writing accurate queries.

This question is often used in interviews because it probes both your grasp of SQL basics and your ability to catch small errors that could lead to significant issues in a production environment.

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