為什么80%的碼農都做不了架構師？>>> ??

Caused by: org.apache.commons.dbcp.SQLNestedException: Cannot create PoolableConnectionFactory (DB2 SQL Error: SQLCODE=-204, SQLSTATE=42704, SQLERRMC=ECBSHIS.DUAL, DRIVER=4.22.29)at org.apache.commons.dbcp.BasicDataSource.createPoolableConnectionFactory(BasicDataSource.java:1549)at org.apache.commons.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:1388)at org.apache.commons.dbcp.BasicDataSource.getConnection(BasicDataSource.java:1044)at org.hibernate.service.jdbc.connections.internal.DatasourceConnectionProviderImpl.getConnection(DatasourceConnectionProviderImpl.java:141)at org.hibernate.internal.AbstractSessionImpl$NonContextualJdbcConnectionAccess.obtainConnection(AbstractSessionImpl.java:301)at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.obtainConnection(LogicalConnectionImpl.java:214)... 69 more Caused by: com.ibm.db2.jcc.am.SqlSyntaxErrorException: DB2 SQL Error: SQLCODE=-204, SQLSTATE=42704, SQLERRMC=ECBSHIS.DUAL, DRIVER=4.22.29at com.ibm.db2.jcc.am.ld.a(ld.java:810)at com.ibm.db2.jcc.am.ld.a(ld.java:66)at com.ibm.db2.jcc.am.ld.a(ld.java:140)at com.ibm.db2.jcc.am.up.c(up.java:2796)at com.ibm.db2.jcc.am.up.d(up.java:2784)at com.ibm.db2.jcc.am.up.a(up.java:2212)at com.ibm.db2.jcc.t4.bb.i(bb.java:148)at com.ibm.db2.jcc.t4.bb.b(bb.java:41)at com.ibm.db2.jcc.t4.p.a(p.java:32)at com.ibm.db2.jcc.t4.vb.i(vb.java:145)at com.ibm.db2.jcc.am.up.lb(up.java:2181)at com.ibm.db2.jcc.am.up.a(up.java:3300)at com.ibm.db2.jcc.am.up.a(up.java:717)at com.ibm.db2.jcc.am.up.executeQuery(up.java:696)at org.apache.commons.dbcp.DelegatingStatement.executeQuery(DelegatingStatement.java:208)at org.apache.commons.dbcp.DelegatingStatement.executeQuery(DelegatingStatement.java:208)at org.apache.commons.dbcp.PoolableConnectionFactory.validateConnection(PoolableConnectionFactory.java:658)at org.apache.commons.dbcp.BasicDataSource.validateConnectionFactory(BasicDataSource.java:1558)at org.apache.commons.dbcp.BasicDataSource.createPoolableConnectionFactory(BasicDataSource.java:1545)... 74 more

解決方法：

DBCP針對不同數據庫的validationQuery 當你使用DBCP連接池時，你可以通過設置testOnBorrow和testOnReturn屬性測試這個連接是否可用。不幸的是你還需要設置validationQuery才能起作用。那么問題來了如何設置validationQuery這個值呢？

什么是validationQuery validationQuery是用來驗證數據庫連接的查詢語句，這個查詢語句必須是至少返回一條數據的SELECT語句。每種數據庫都有各自的驗證語句，下表中收集了幾種常見數據庫的validationQuery。

• DataBase validationQuery

• hsqldb select 1 from INFORMATION_SCHEMA.SYSTEM_USERS

• Oracle select 1 from dual

• DB2 select 1 from sysibm.sysdummy1

• MySql select 1

• Microsoft SqlServer select1

• postgresql select version()

• ingres select 1

• derby values 1

• H2 select 1

根據JDBC驅動獲取validationQuery 如果你想支持多種數據庫，你可以根據JDBC驅動來獲取validationQuery，這里有個簡單的類，根據JDBC驅動名稱來獲取validationQuery

轉載于:https://my.oschina.net/saulc/blog/1785825

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