• Apabila menggunakan jdbc untuk menyambung ke pangkalan data postgresql, ralat adalah seperti berikut:

org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.exceptions.PersistenceException: 
### Error querying database.  Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Could not get JDBC Connection; nested exception is org.apache.commons.dbcp.SQLNestedException: Cannot create PoolableConnectionFactory (????????: ?????? "uav_test " ??????)
### The error may exist in file [G:\Uav\NewMavenDemo\target\classes\mapper\UserMapper.xml]
### The error may involve UserMapper.getUserInfo
### The error occurred while executing a query
### Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Could not get JDBC Connection; nested exception is org.apache.commons.dbcp.SQLNestedException: Cannot create PoolableConnectionFactory (????????: ?????? "uav_test " ??????)
    at org.mybatis.spring.MyBatisExceptionTranslator.translateExceptionIfPossible(MyBatisExceptionTranslator.java:79)
    at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:447)
    at com.sun.proxy.$Proxy27.selectList(Unknown Source)

• Mesej ralat utama: Cannot create PoolableConnectionFactory (????????: ?????? "uav_test " ??????)

• Parameter sambungan adalah seperti berikut:

#Postgresql  
driver=org.postgresql.Driver
url=jdbc:postgresql://localhost:5432/uav_test 
username=postgres
password=root
dialect=postgresql

• Tiada masalah apabila saya menukar pangkalan data postgresql untuk menggunakan mysql Parameter untuk mysql:

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/mysql
username=root
password=root
dialect=mysql 

• Saya tidak begitu faham mengapa ini berlaku