How Can I Write Cross-Database SQL Test Queries for Connection Validation?

Cross-Database SQL Test Queries for Connection Validation

To ensure uninterrupted database connections, SQL test queries are used to periodically verify connection availability. However, selecting the appropriate query becomes challenging, given the diverse vendor ecosystems. Here, we explore vendor-specific and universally applicable solutions for this concern.

Vendor-Specific Queries:

• MySQL, H2, SQL Server, PostgreSQL, SQLite, Hive: SELECT 1
• Oracle: SELECT 1 FROM DUAL

Universally Compatible Queries:

While a universally compatible query may not exist, the following suggestions offer broad coverage across multiple databases:

• SELECT 1 FROM any_existing_table WHERE 1=0 or SELECT 1 FROM INFORMATION_SCHEMA.SYSTEM_USERS or CALL NOW(): HSQLDB
• Apache Derby: VALUES 1 or SELECT 1 FROM SYSIBM.SYSDUMMY1
• DB2: SELECT 1 FROM SYSIBM.SYSDUMMY1
• Informix: select count(*) from systables

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