PLSQL JDBC：如何獲取最後一行ID？

Question

什麼是PLSQL（Oracle）等同於此SQL服務器片段？

BEGIN TRAN 
INSERT INTO mytable(content) VALUES ("test") -- assume there's an ID column that is autoincrement 
SELECT @@IDENTITY 
COMMIT TRAN 

在C＃中，您可以調用myCommand.ExecuteScalar（）來檢索新行的ID。

如何在Oracle中插入新行，並讓JDBC獲得新ID的副本？

編輯： BalusC提供了一個非常好的起點。出於某種原因，JDBC不喜歡命名參數綁定。這會給出「錯誤地設置或註冊參數」SQLException。這是爲什麼發生？

 OracleConnection conn = getAppConnection(); 
     String q = "BEGIN INSERT INTO tb (id) values (claim_seq.nextval) returning id into :newId; end;" ; 
     CallableStatement cs = (OracleCallableStatement) conn.prepareCall(q); 
     cs.registerOutParameter("newId", OracleTypes.NUMBER); 
     cs.execute(); 
     int newId = cs.getInt("newId"); 

Answer 1

通常你會使用Statement#getGeneratedKeys()這個（見this answer的例子），但是這是遠（還）不是由Oracle JDBC驅動程序的支持。

你最好的賭注是要麼化妝用的CallableStatement與RETURNING條款：

String sql = "BEGIN INSERT INTO mytable(id, content) VALUES (seq_mytable.NEXTVAL(), ?) RETURNING id INTO ?; END;"; 

Connection connection = null; 
CallableStatement statement = null; 

try { 
    connection = database.getConnection(); 
    statement = connection.prepareCall(sql); 
    statement.setString(1, "test"); 
    statement.registerOutParameter(2, Types.NUMERIC); 
    statement.execute(); 
    int id = statement.getInt(2); 
    // ... 

或者火SELECT sequencename.CURRVALINSERT後，在同一個事務：

String sql_insert = "INSERT INTO mytable(content) VALUES (?)"; 
String sql_currval = "SELECT seq_mytable.CURRVAL FROM dual"; 

Connection connection = null; 
PreparedStatement statement = null; 
Statement currvalStatement = null; 
ResultSet currvalResultSet = null; 

try { 
    connection = database.getConnection(); 
    connection.setAutoCommit(false); 
    statement = connection.prepareStatement(sql_insert); 
    statement.setString(1, "test"); 
    statement.executeUpdate(); 
    currvalStatement = connection.createStatement(); 
    currvalResultSet = currvalStatement.executeQuery(sql_currval); 
    if (currvalResultSet.next()) { 
     int id = currvalResultSet.getInt(1); 
    } 
    connection.commit(); 
    // ... 

Answer 2

您可以使用Oracle的returning子句。

insert into mytable(content) values ('test') returning your_id into :var; 

查看this link代碼示例。您需要Oracle 10g或更高版本以及新版本的JDBC驅動程序。

Answer 3

您可以使用getGeneratedKeys（），通過顯式選擇關鍵字段。 這裏是一個片段：

// change the string to your connection string 
    Connection connection = DriverManager.getConnection("connection string"); 

    // assume that the field "id" is PK, and PK-trigger exists 
    String sql = "insert into my_table(id) values (default)"; 
    // you can select key field by field index 
    int[] colIdxes = { 1 }; 
    // or by field name 
    String[] colNames = { "id" }; 

    // Java 1.7 syntax; try-finally for older versions 
    try (PreparedStatement preparedStatement = connection.prepareStatement(sql, colNames)) 
    { 
     // note: oracle JDBC driver do not support auto-generated key feature with batch update 
     //   // insert 5 rows 
     //   for (int i = 0; i < 5; i++) 
     //   { 
     //    preparedStatement.addBatch(); 
     //   } 
     //   
     //   int[] batch = preparedStatement.executeBatch(); 
     preparedStatement.executeUpdate(); 

     // get generated keys 
     try (ResultSet resultSet = preparedStatement.getGeneratedKeys()) 
     { 
      while (resultSet.next()) 
      { 
       // assume that the key's type is BIGINT 
       long id = resultSet.getLong(1); 
       assertTrue(id != 0); 

       System.out.println(id); 
      } 
     } 
    } 

參閱有關詳情：http://docs.oracle.com/cd/E16655_01/java.121/e17657/jdbcvers.htm#CHDEGDHJ