EXISTS Subqueries: `SELECT *` vs. `SELECT 1` – Which Improves Readability?

EXISTS Subqueries: What Enhances Readability?

In the realm of SQL,EXISTS subqueries serve a crucial purpose in data retrieval. However, when faced with the choice between using EXISTS (SELECT *) and EXISTS (SELECT 1) within subqueries, some may question which syntax offers superior readability.

The Significance of EXISTS

The key aspect to consider is that the EXISTS keyword itself holds the primary significance in the subquery. Whether * or 1 appears within the parentheses is largely inconsequential. The primary focus is on the existence of at least one row in the subquery's result set.

The Argument for EXISTS (SELECT *)

Advocates of EXISTS (SELECT ) argue that using aligns with the natural language interpretation of" exists." This construct conveys the notion of searching for any record's existence, not a specific record.

The Case for EXISTS (SELECT 1)

Proponents of EXISTS (SELECT 1) argue that it offers greater simplicity. They contend that explicitly selecting 1 clarifies the subquery's purpose: to determine if at least one matching row exists. Moreover, they assert that this syntax better aligns with the broader usage of selecting 1 in SQL queries.

The Standards Perspective

The ANSI standard for SQL provides clarity on this matter. It explicitly states that the choice between * and 1 within EXISTS subqueries is arbitrary. Both formats are equally valid and perform identically.

Conclusion

The question of which syntax is easier to read is ultimately subjective. While EXISTS (SELECT *) may resonate with those accustomed to natural language interpretation, EXISTS (SELECT 1) offers simplicity and aligns with other SQL conventions.Ultimately, the choice depends on the personal preferences of the SQL developer.

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