Java ApacheDerbyID列应该一个接一个地自动递增-但它没有,为什么?
我试图创建一个ApacheDerby表,并通过JDBC接口在其中插入数据 以下是我的实现的简短摘录:Java ApacheDerbyID列应该一个接一个地自动递增-但它没有,为什么?,java,jdbc,derby,Java,Jdbc,Derby,我试图创建一个ApacheDerby表,并通过JDBC接口在其中插入数据 以下是我的实现的简短摘录: public class SQLDatabase { private Connection connection = null; public final static String HOME_DIRECTORY = System.getProperty("user.home"); public final static String TABLE_NAME = "POR
public class SQLDatabase {
private Connection connection = null;
public final static String HOME_DIRECTORY = System.getProperty("user.home");
public final static String TABLE_NAME = "PORPHYRIE";
public SQLDatabase() {
setConnection();
if (!(isTableExisting(TABLE_NAME))) {
createTable();
}
}
// OTHER
public void createTable() {
String statement = "CREATE TABLE PORPHYRIE("
+ "ID int NOT NULL GENERATED ALWAYS AS IDENTITY"
+ "(START WITH 1,INCREMENT BY 1)," + "ENTRYDATE DATE NOT NULL,"
+ "DRUGTYPE varchar(255) NOT NULL,"
+ "UPPERLIMIT DOUBLE NOT NULL," + "NORMOSANG BOOLEAN NOT NULL,"
+ "MENSTRUATION BOOLEAN NOT NULL,"
+ "DRUGAMOUNT_MG DOUBLE NOT NULL,"
+ "DRUGAMOUNT_ML DOUBLE NOT NULL,"
+ "AMPOULE_NUMBERS DOUBLE NOT NULL,"
+ "RECORDDATE DATE NOT NULL," + "PRIMARY KEY(ID)" + ")";
updateStatement(statement);
}
public void dropTable() {
String statement = "DROP TABLE PORPHYRIE";
updateStatement(statement);
}
public void addData(EntryPoint entry) {
DrugAmount drugAmount = entry.getDrugAmountObject();
SimpleDateFormat form = new SimpleDateFormat("dd.MM.yyyy");
String statement = "INSERT INTO PORPHYRIE (ENTRYDATE,DRUGTYPE,UPPERLIMIT,NORMOSANG,MENSTRUATION,DRUGAMOUNT_MG,DRUGAMOUNT_ML,AMPOULE_NUMBERS,RECORDDATE)"
+ " values('"
+ form.format(entry.getEntryDate().getTime())
+ "','"
+ entry.DRUG_TYPE_DOLANTIN
+ "',"
+ entry.DRUG_UPPER_LIMIT
+ ","
+ entry.getNormoSang()
+ ","
+ entry.getMenstruation()
+ ","
+ drugAmount.getAmpoulesInMG()
+ ","
+ drugAmount.getAmpoulesInML()
+ ","
+ drugAmount.getNumberOfAmpoules() + ",CURRENT_DATE)";
System.out.println("Add data!");
updateStatement(statement);
}
private void setConnection() {
try {
Class.forName("org.apache.derby.jdbc.EmbeddedDriver");
connection = DriverManager.getConnection("jdbc:derby:"
+ HOME_DIRECTORY + "\\MyDB;create=true");
} catch (ClassNotFoundException | SQLException e) {
e.printStackTrace();
}
}
private void updateStatement(String statementString) {
try {
PreparedStatement preparedStatement = getConnection()
.prepareStatement(statementString);
preparedStatement.executeUpdate();
} catch (SQLException e) {
e.printStackTrace();
}
}
这就是我得到的:
ID列有什么问题
第一次创建SQL数据库对象时,应该创建表,这很好。
然后,您应该能够通过addData()方法插入一些数据,这看起来也不错。
但是,如果您创建一个新的SQL数据库对象并在中使用addData-method(),那么它会添加数据(上图中的第五行),但不会正确地自动递增。这里怎么了 生成的序列号中的间隔是Derby的正确且有文档记录的行为 比如说,
而且:正如Bryan所描述的,这个错误是众所周知的。但好的是,您可以使用以下方法解决此问题:
DriverManager.getConnection(“jdbc:derby:;shutdown=true”)代码>
这将关闭derby中的所有数据库,您可以始终指定要关闭的数据库
DriverManager.getConnection(“jdbc:derby:+HOME\u DIRECTORY+”\\MyDB;shutdown=true”)
问题是,无论何时注销或关闭应用程序,我们都必须关闭derby db,然后只正确插入值,否则缓存值会阻止在数据库表中准确插入值
请遵循以下步骤:
con=DriverManager.getConnection(“jdbc:derby:+“db”+“create=true”);->这是为了通过提及“db”名称来加载derby db。我们必须将此代码放入您的应用程序登录操作中
getConnection(“jdbc:derby:+“db”+“shutdown=true”);->这是用于关闭数据库“db”。我们必须将此代码放在您的应用程序注销操作或关闭位置
注意:这是针对嵌入式数据库的