当我运行代码时出现此错误
Exception in thread "main" java.sql.SQLException: Can't create table 'Sensors_db.one' (errno: 121)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1073)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3609)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3541)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2002)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2163)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2624)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2127)
at com.mysql.jdbc.PreparedStatement.execute(PreparedStatement.java:1362)
at sensordev.SensorDev.sensorPage(SensorDev.java:283)
at sensordev.SensorDev.main(SensorDev.java:893)
以下是我的代码
String type = "37";
String senName = "one";
String query;
switch(type){
case "37":{
query = "CREATE TABLE IF NOT EXISTS `"+ senName +"` ("
+ " `Name` VARCHAR(45) NOT NULL,"
+ " `State` VARCHAR(45) NOT NULL,"
+ " `Time` TIME NOT NULL,"
+ " PRIMARY KEY (`Time`, `State`),"
+ " INDEX `fk_dummy_1_idx` (`Name` ASC),"
+ " CONSTRAINT `fk_dummy_1`"
+ " FOREIGN KEY (`Name`)"
+ " REFERENCES `Sensors_db`.`sensorInfo` (`SName`)"
+ " ON DELETE NO ACTION"
+ " ON UPDATE NO ACTION);";
defaultStmt = conn.prepareStatement(query);
defaultStmt.execute();
“conn”是我的数据库实例，“defaultStmt”是一个PreparedStatement
最佳答案
err 121 表示约束名称已被使用。更改您的约束名称。约束名称在数据库中应该是唯一的。
查看约束是否已存在。
SELECT
table_name
FROM
information_schema.table_constraints
WHERE
constraint_type = 'FOREIGN KEY'
AND table_schema = DATABASE() AND
constraint_name = 'fk_dummy_1'
关于java - SQL异常:can not create table，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/32839886/