Testquery/validationquery settings for the JDBC Connection pool

You want to increase the test/validation of connections in the connection pool to prevent the database from thinking that the connection is dead and that the Web application server thinks the connection is still valid in the "Timeout problem with connector/j connection to MySQL in Tomcat" post. The MySQL documentation mentions the examples in the Tomcat document are validationquery, but there are a lot of posts on the web that are written by Testquery, which one does it use?

This is related to the implementation of the connection pool:

connection Pooling Implementation	the Feature property name
The Tomcat JDBC Connection Pool	Validationquery
The Apache Commons DBCP Connection Pool	Validationquery
C3P0-JDBC3 Connection and Statement Pooling	Preferredtestquery
Atomikos:tomcat Spring ActiveMQ MySQL JMX Integration Analysis Atomikos data Connection pool source code, understand Testquery	Testquery

Also, the SQL statement that tests/verifies connection pooling connections varies by database:
Efficient SQL test query or validation query that would work across all (or most) databases
Dbcp-validationquery for different Databases

Combining the two posts, the summary results are as follows:

Database	test/Validate Query
Mysql	SELECT 1
PostgreSQL	SELECT 1
Microsoft SQL Server	SELECT 1
Sqlite	SELECT 1
H2	SELECT 1
Ingres	SELECT 1
Oracle	Select 1 from dual
DB2	Select 1 from Sysibm.sysdummy1 or SELECT Current date from sysibm.sysdummy1
Apache Derby	VALUES 1 from SYSIBM. SYSDUMMY1 or SELECT 1 from SYSIBM. SYSDUMMY1
Hsqldb	SELECT 1 from any_existing_table WHERE 1=0 or SELECT 1 from INFORMATION_SCHEMA. System_users
Informix	Select COUNT (*) from Systables

Testquery/validationquery settings for the JDBC Connection pool