Question

我正在使用oracle数据库。当我尝试使用单个选择查询获取数据时，它返回了数据集中的单个表。如何在oracle中编写一个select查询或过程，在那里我可以获得一个包含2-3（多个）表的数据集？

Answer 1

据我了解你的问题，你想减少往返数据库的次数。这可以通过以下方式通过存储过程完成：

http://msdn.microsoft.com/en-us/library/ms971506.aspx#msdnorsps_topic6

包标题：

CREATE OR REPLACE PACKAGE SELECT_JOB_HISTORY AS
TYPE T_CURSOR IS REF CURSOR;
PROCEDURE GetJobHistoryByEmployeeId
(
    p_employee_id IN NUMBER,
    cur_JobHistory OUT T_CURSOR
);
END SELECT_JOB_HISTORY;

包装：

CREATE OR REPLACE PACKAGE BODY SELECT_JOB_HISTORY AS
PROCEDURE GetJobHistoryByEmployeeId
(
    p_employee_id IN NUMBER,
    cur_JobHistory OUT T_CURSOR
)
IS
BEGIN
    OPEN cur_JobHistory FOR
    SELECT * FROM JOB_HISTORY
        WHERE employee_id = p_employee_id;

END GetJobHistoryByEmployeeId;
END SELECT_JOB_HISTORY;

客户端：

// create connection
OracleConnection conn = new OracleConnection("Data Source=oracledb;
    User Id=UserID;Password=Password;");

// create the command for the stored procedure
OracleCommand cmd = new OracleCommand();
cmd.Connection = conn;
cmd.CommandText = "SELECT_JOB_HISTORY.GetJobHistoryByEmployeeId";
cmd.CommandType = CommandType.StoredProcedure;

// add the parameters for the stored procedure including the REF CURSOR
// to retrieve the result set
cmd.Parameters.Add("p_employee_id", OracleType.Number).Value = 101;
cmd.Parameters.Add("cur_JobHistory", OracleType.Cursor).Direction =
    ParameterDirection.Output;

// open the connection and create the DataReader
conn.Open();
OracleDataReader dr = cmd.ExecuteReader();

// output the results and close the connection.
while(dr.Read())
{
    for(int i = 0; i < dr.FieldCount; i++)
        Console.Write(dr[i].ToString() + ";");
    Console.WriteLine();
}
conn.Close();

如果你必须加入这些表，你也可以使用普通连接并在客户端上拆分结果（imho这就是很多ORM的工作方式）。

Answer 2

这正是我所做的，很简单：

        Database db = DatabaseFactory.CreateDatabase("ConnectionString");
        object[] results = new object[3];
        DbCommand cmd = db.GetStoredProcCommand("DATABASE.SELECT_JOB_HISTORY.GetJobHistoryByEmployeeId",results);            
        DataSet ds = db.ExecuteDataSet(cmd);
        DataTable dt1 = ds.Tables[0];
        DataTable dt2 = ds.Tables[1];

Oracle查询/存储过程返回多个结果集

2 个答案: