Why Should I Avoid Using `SELECT *` in SQL Queries?

*Why `SELECT ` is a Bad Practice in SQL**

The common advice "don't optimize prematurely" doesn't apply to SELECT *. Using SELECT * reduces code clarity and makes performance profiling significantly harder. It's an anti-pattern that masks performance bottlenecks.

Better Alternatives: Selecting Specific Columns

Explicitly listing columns offers several advantages:

1. Robust Error Handling: If table columns change, queries with specified columns will fail gracefully, highlighting the problem. SELECT * silently hides these errors.
2. Improved Code Readability: Clearly stating the required columns makes the code's purpose immediately apparent.
3. Reduced Data Transfer: Fetching only necessary columns minimizes network traffic and database load.
4. Avoid Ordinal Access Issues: Using ordinal column access (e.g., SELECT column_1, column_2) is risky with SELECT * as column order might change unexpectedly.
5. Efficient Join Handling: In joins, SELECT * retrieves all columns from all tables, resulting in unnecessary data retrieval.

*Negative Impacts of `SELECT `**

Using SELECT * leads to:

1. Hidden Application Logic: The application's data needs are obscured, making maintenance and understanding difficult.
2. Performance Bottlenecks: Performance analysis is hindered, making database optimization challenging.
3. Fragile Code: Schema changes can break SELECT * queries, increasing maintenance costs.
4. Excessive Resource Consumption: Unnecessary data transfer burdens the network and storage.
5. Suboptimal Database Optimization: The database engine can't optimize queries retrieving all columns effectively.

In Summary:

Although SELECT * appears convenient, it's best avoided. Explicitly selecting columns improves code clarity, error handling, performance, and simplifies database management.

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