How to Handle Missing Database Records and Return a NULL Default Value in SQL?

Selecting a Default Value in Absence of Database Records

The provided SQL statement fails when the specified number is not present in the database table. This article presents a solution that encapsulates the query within a sub-query to assign a default value of NULL in such scenarios.

Encapsulating the Query

Encapsulating the original query within a sub-query effectively transforms the absence of a result into a NULL value. This approach is compatible with various database management systems, including:

• PostgreSQL
• SQLite
• SQL Server
• MySQL
• Oracle

Implementation

PostgreSQL, SQLite, SQL Server, and MySQL

SELECT (SELECT id FROM tbl WHERE id = 9823474) AS id;

Oracle (use from DUAL table)

SELECT (SELECT id FROM tbl WHERE id = 9823474) AS id FROM DUAL;

Firebird

SELECT (SELECT id FROM tbl WHERE id = 9823474) AS id FROM RDB$DATABASE;

DB2

SELECT (SELECT id FROM tbl WHERE id = 9823474) AS id FROM SYSIBM.SYSDUMMY1;

By implementing this solution, you can ensure that your SQL statements gracefully return a default value of NULL instead of encountering errors when the queried data is not present in the database.

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