Java 如何将主键的Id填充到外键
我刚刚开始学习Java JDBC,我试图创建一个示例项目,我创建了两个准备好的语句,在其中为我的表插入了两个查询。第一个表用于主键,第二个表用于外键。使用语句_RETURN.GENERATED_KEYS返回主键的Id,但在我的外键中,它不会填充并向我抛出null值 父表 子表 查询:Java 如何将主键的Id填充到外键,java,sql,database,jdbc,Java,Sql,Database,Jdbc,我刚刚开始学习Java JDBC,我试图创建一个示例项目,我创建了两个准备好的语句,在其中为我的表插入了两个查询。第一个表用于主键,第二个表用于外键。使用语句_RETURN.GENERATED_KEYS返回主键的Id,但在我的外键中,它不会填充并向我抛出null值 父表 子表 查询: String insertALLSECTION_LIST = "INSERT INTO ALLSECTIONS_LIST (SECTION_NAME)" + "VALUES (?
String insertALLSECTION_LIST = "INSERT INTO ALLSECTIONS_LIST (SECTION_NAME)"
+ "VALUES (?)";
String insertALLSECTIONS_SETTINGS = "INSERT INTO ALLSECTIONS_SETTINGS (SECTION_POPULIMIT,ROOM_ASSGN,ADVISER_ASSIGNED,SESSION_ASSIGNED,YRLEVEL_ASSGN,SCHOOL_YEAR)"
+ "VALUES(?,?,?,?,?,?)";
准备好的声明
ResultSet generatedKeys = null;
try (Connection myConn = DBUtil.connect())//Connection
{
myConn.setAutoCommit(false);//Turn off auto commit
try (PreparedStatement myPs = myConn.prepareStatement(insertALLSECTION_LIST,Statement.RETURN_GENERATED_KEYS))//Prepared Statement
{
myPs.setString(1,inputSectionName);
myPs.executeUpdate();
myConn.commit();
generatedKeys = myPs.getGeneratedKeys();
if (generatedKeys.next())//Return ID
{
sectionID = generatedKeys.getInt(1);
}
else
{
throw new SQLException("No generated section ID returned");
}
}//end of try
finally
{
if (generatedKeys != null) generatedKeys.close();
}//end of finally
try (PreparedStatement myPs = myConn.prepareStatement(insertALLSECTIONS_SETTINGS))//Prepared Statement
{
myPs.setInt(1,inputStudentLimit);
myPs.setString(2, inputRoomAssign);
myPs.setString(3, inputAdviserAssign);
myPs.setString(4, inputSession);
myPs.setString(5, inputYearLevel);
myPs.setString(6, inputSchoolYear);
myPs.executeUpdate();
myConn.commit();
JOptionPane.showMessageDialog(null, "Insert Successful");
}//end of try
}//end of try
第一个表格(所有章节列表)
正如您在这里看到的,主键正在填充
第二张表格(所有章节设置)
在这里,我的SECTION\u ID列给我空值
但当我对我的表运行查询时。仍然为我的外键提供空值。请随意评论。谢谢。一旦您从第一条准备好的语句中获得自动生成的密钥,您就必须手动将其插入到另一个表中 以下是修改后的查询:
String insertALLSECTION_LIST = "INSERT INTO ALLSECTIONS_LIST (SECTION_NAME)"
+ "VALUES (?)";
String insertALLSECTIONS_SETTINGS = "INSERT INTO ALLSECTIONS_SETTINGS (SECTION_ID,
SECTION_POPULIMIT,ROOM_ASSGN,ADVISER_ASSIGNED,
SESSION_ASSIGNED,YRLEVEL_ASSGN,SCHOOL_YEAR)"
+ "VALUES(?,?,?,?,?,?,?)";
以下是代码片段:
ResultSet generatedKeys = null;
try (Connection myConn = DBUtil.connect()) {
myConn.setAutoCommit(false);
try (PreparedStatement myPs = myConn.prepareStatement(insertALLSECTION_LIST,
Statement.RETURN_GENERATED_KEYS)) {
myPs.setString(1,inputSectionName);
myPs.executeUpdate();
myConn.commit();
generatedKeys = myPs.getGeneratedKeys();
if (generatedKeys.next()) {
sectionID = generatedKeys.getInt(1);
} else {
throw new SQLException("No generated section ID returned");
}
} finally {
if (generatedKeys != null) generatedKeys.close();
}
try (PreparedStatement myPs = myConn.prepareStatement(insertALLSECTIONS_SETTINGS)) {
/* Note : Change Here */
myPs.setInt(1, sectionID);
myPs.setInt(2, inputStudentLimit);
myPs.setString(3, inputRoomAssign);
myPs.setString(4, inputAdviserAssign);
myPs.setString(5, inputSession);
myPs.setString(6, inputYearLevel);
myPs.setString(7, inputSchoolYear);
myPs.executeUpdate();
myConn.commit();
JOptionPane.showMessageDialog(null, "Insert Successful");
}
}
返回生成的键的语句返回主键的Id,但它不填充在外键中。我有点困惑。我看不到您将从第一个PS获得的密钥,即
sectionID
,插入到第二个PS的任何位置。我错过什么了吗?嗨@user2004685我刚刚更新了我的帖子。请再检查一遍。谢谢给你投票,兄弟!我已经知道我的错误了。我发现我需要手动插入到其他表中。我认为自动生成的键会自动将值插入到我的第二个表中。谢谢@米娅:不客气