如何从 firebird 数据库向 C# 程序提示消息插入过程

Question

我在 firebird 中有一个插入程序，它的作用是验证我要保存的数据是否存在于 table 中。如果我要保存的数据存在于 table 中，那么数据将不会被保存。如果是这种情况，我将如何提示用户因为数据存在而未保存数据？

这是我的插入过程

    CREATE PROCEDURE TRAINTRN_INSERT(
  EMP_PK INTEGER,
  TRAINTRN_EMP_TYPE VARCHAR(50) CHARACTER SET ISO8859_1 COLLATE ISO8859_1,
  TRAINTRN_BATCH VARCHAR(50) CHARACTER SET ISO8859_1 COLLATE ISO8859_1,
  TRAINTRN_AREA VARCHAR(100) CHARACTER SET ISO8859_1 COLLATE ISO8859_1,
  TRAINTRN_SRCVCRDT DECIMAL(12, 2),
  TRAINING_PK INTEGER,
  USER_PK SMALLINT,
  TRAINTRN_UPDATETIME TIMESTAMP)
AS
DECLARE VARIABLE EXSTING_EMP_PK INTEGER;
DECLARE VARIABLE EXSTING_TRAINING_PK INTEGER;
BEGIN
 FOR
SELECT  
       COUNT(A.EMP_PK)
FROM TRAINTRN_TABLE A WHERE A.TRAINING_PK =: TRAINING_PK AND  A.EMP_PK =: EMP_PK
INTO
:EXSTING_EMP_PK
DO

IF (EXSTING_EMP_PK = 0) THEN
BEGIN
  INSERT INTO TRAINTRN_TABLE (
    EMP_PK,
    TRAINTRN_EMP_TYPE,
    TRAINTRN_BATCH,
    TRAINTRN_AREA,
    TRAINTRN_SRCVCRDT,
    TRAINING_PK,
    USER_PK,
    TRAINTRN_UPDATETIME)
  VALUES (
    :EMP_PK,
    :TRAINTRN_EMP_TYPE,
    :TRAINTRN_BATCH,
    :TRAINTRN_AREA,
    :TRAINTRN_SRCVCRDT,    
    :TRAINING_PK,
    :USER_PK,
    CURRENT_TIMESTAMP);
    END
END;

这是我的 c#

代码

var adder = new ClsHR();
adder.SaveParticipants();

XtraMessageBox.Show("Successfully Added.", "Save ",
MessageBoxButtons.OK, MessageBoxIcon.Asterisk);

public void SaveParticipants()
        {
            try
            {
                var adder = new FbConnection(ClsConnection.FirebirdSQL);
                var fbcmd = new FbCommand("TRAINTRN_INSERT", adder)
                {
                    CommandType = CommandType.StoredProcedure
                };
                fbcmd.Parameters.Add("@EMP_PK", FbDbType.VarChar).Value = UpdtHndlrEmp;
                fbcmd.Parameters.Add("@TRAINTRN_EMP_TYPE", FbDbType.VarChar).Value = TRAINTRN_EMP_TYPE;
                fbcmd.Parameters.Add("@TRAINTRN_BATCH", FbDbType.VarChar).Value = TRAINTRN_BATCH;
                fbcmd.Parameters.Add("@TRAINTRN_AREA", FbDbType.VarChar).Value = TRAINTRN_AREA;
                fbcmd.Parameters.Add("@TRAINTRN_SRCVCRDT", FbDbType.VarChar).Value = TRAINTRN_SRCVCRDT;
                fbcmd.Parameters.Add("@TRAINING_PK", FbDbType.VarChar).Value = UpdateHandler;
                fbcmd.Parameters.Add("@USER_PK", FbDbType.SmallInt).Value = ClsEmployee.USER_PK;
                fbcmd.Parameters.Add("@TRAINTRN_UPDATETIME", FbDbType.VarChar).Value = EventTimestamp;
                fbcmd.Connection.Open();
                fbcmd.ExecuteNonQuery();
                fbcmd.Connection.Close();
            }
            catch (Exception errorcode)
            {
                XtraMessageBox.Show(String.Format("Error in connection: {0}. Saving failed.", errorcode.Message), @"Server Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
            }
        }

Answer 1

您可以创建一个 exception。

CREATE EXCEPTION MY_EXCEPTION 'Exception text';

如果数据存在，则在存储过程中调用异常：

IF (EXSTING_EMP_PK = 0) THEN
BEGIN
  INSERT INTO TRAINTRN_TABLE (
    EMP_PK,
    .....
END
ELSE
  EXCEPTION MY_EXCEPTION;

然后在 C 代码中你可能会像往常一样得到异常。

另一种方式：

只是 return 来自存储过程的结果，例如：

IF (EXSTING_EMP_PK = 0) THEN
BEGIN
  INSERT INTO TRAINTRN_TABLE (
    EMP_PK,
    .....
  OUTPUT_RESULT = 1;
END
ELSE
  OUTPUT_RESULT = 0;

SUSPEND;

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