解决MySQL8.0报错java.sql.SQLException: Unknown system variable 'tx_isolation'

刺骨的言语ヽ痛彻心扉 2023-07-13 15:25 14阅读 0赞

项目连接RDS的时候遇到了个问题  
日志信息提示 没有tx\_isolation这个系统变量

DEBUG [C3P0PooledConnectionPoolManager[identityToken->1hgeby9a81m7jt0f4mukia|1bdac937]-HelperThread-#1] - An exception occurred while acquiring a poolable resource. Will retry.
    java.sql.SQLException: Unknown system variable 'tx_isolation'
    	at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1084)
    	at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4232)
    	at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4164)
    	at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2615)
    	at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2776)
    	at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2832)
    	at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2781)
    	at com.mysql.jdbc.StatementImpl.executeQuery(StatementImpl.java:1569)
    	at com.mysql.jdbc.ConnectionImpl.getTransactionIsolation(ConnectionImpl.java:3380)
    	at com.mchange.v2.c3p0.impl.NewPooledConnection.<init>(NewPooledConnection.java:120)
    	at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:240)
    	at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:206)
    	at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:203)
    	at com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1138)
    	at com.mchange.v2.resourcepool.BasicResourcePool.doAcquireAndDecrementPendingAcquiresWithinLockOnSuccess(BasicResourcePool.java:1125)
    	at com.mchange.v2.resourcepool.BasicResourcePool.access$700(BasicResourcePool.java:44)
    	at com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask.run(BasicResourcePool.java:1870)
    	at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:696)

## 原因： ##

mysql-connector-java的版本太低 数据库的版本太高  
因此须将mysql-connector-java**升级到最新版本**  
之前用的是版本是5

<dependency>
      <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.30</version>
    </dependency>

改成8

<dependency>
      <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.15</version>
    </dependency>

然后驱动名称改为`com.mysql.cj.jdbc.Driver`

### 至此 问题解决 ###

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