c# - 为什么 ExecuteNonQuery 捕获异常 {"validation error for column \"ORGTABLE\".\"FIKEYID\", value \"* null *\""}

Question

为什么 ExecuteNonQuery 捕获异常 {"validation error for column \"ORGTABLE\".\"FIKEYID\", value \" * null * \""}

string stValuesPlaceHolder = "@p0";
for (int iii = 1; iii < liststFieldValuesNoKeyId.Count; iii++)
    stValuesPlaceHolder += ", @p" + (iii).ToString();

FbTransaction fbTransaction = fbConn.BeginTransaction();
FbCommand fbCmd = new FbCommand("INSERT INTO " + stTableName + "(" + stFieldNamesNoKeyId + ") VALUES ( " + stValuesPlaceHolder + " )", fbConn, fbTransaction);

for (int iii = 0; iii < liststFieldValuesNoKeyId.Count; iii++) {
    string stPlaceHolder = "@p" + (iii).ToString();
    string stValue = liststFieldValuesNoKeyId[iii];
    fbCmd.Parameters.AddWithValue(stPlaceHolder, stValue);
}

fbCmd.ExecuteNonQuery();
fbTransaction.Commit();

stTableName 是 OrgTable。

字段名称为：

fstPriority, fstInfo, fstDateCreated, fstDateModified, fiKeyID.

字段定义如下：

fstPriority VARCHAR(30), fstInfo VARCHAR(100), fstDateCreated VARCHAR(30), fstDateModified VARCHAR(30), fiKeyID INTEGER PRIMARY KEY

---

在这部分代码中：

stFieldNamesNoKeyId = "fstPriority, fstInfo, fstDateCreated, fstDateModified".

stValuesPlaceHolder = "@p0, @p1, @p2, @p3"

四个 fbCmd.Parameters.AddWithValue：

stPlaceHolder = "@p0" ... stValue = "1st value";

stPlaceHolder = "@p1" ... stValue = "2nd value";

stPlaceHolder = "@p2" ... stValue = "3rd value";

stPlaceHolder = "@p3" ... stValue = "4th value";

我没有为 fiKeyID 添加一个值，因为它作为主键。

Answer 1

我没有为 fiKeyID 添加一个值，因为它作为主键。

所以你尝试插入一个 NULL 主键。这是不允许的。

http://www.firebirdsql.org/manual/nullguide-keys.html

主键中决不允许使用 NULL。如果在列定义或域定义中将列定义为 NOT NULL，则该列只能是（部分）PK。

然后，您可能想向服务器询问自动生成的 ID。有几种方法可以做到这一点。

例如，Firebird 3 带有 auto-inc 列类型。这是数据库开发人员之前明确使用的工具的语法糖。

Firebird 2 和之前的版本使用 GENERATORS（又名 SQL SEQUENCE）来实现它。

您必须在表上创建一个 BEFORE-INSERT（或 BEFORE-INSERT-OR-UPDATE）触发器，如果​​ ID 字段为 NULL，它将填充生成器的 ID 字段。 http://www.firebirdfaq.org/faq29/

CREATE GENERATOR gen_t1_id;
SET GENERATOR gen_t1_id TO 0;
set term !! ;
 CREATE TRIGGER T1_BI FOR T1
 ACTIVE BEFORE INSERT POSITION 0
 AS
 BEGIN
 if (NEW.ID is NULL) then NEW.ID = GEN_ID(GEN_T1_ID, 1);
 END!!
set term ; !!

归结为您的 SQL 访问库。因为通常在插入行之后 - 您必须知道它的 ID。

如果你不关心新生儿行的那个 ID，你可以跳过其余的。

但是，如果您既想插入行又想知道它的 ID，那么它归结为另一种选择。

低技术含量的纯 SQL 库会迫使您进行两次往返：

• SELECT GEN_ID(GEN_T1_ID, 1) FROM RDB$DATABASE或者SELECT NEXT VALUE FOR GEN_T1_ID FROM RDB$DATABASE为您保留一个免费令牌，然后您将显式地将您的 ID PK 列分配给该值并将其与数据列一起插入，绕过触发器。

• 或者使用高级 SQL 库，您可以要求 Firebird 自动计算价值并将其报告给您：INSERT INTO tablename(data1,data2,dataq3) VALUES (1,2,3) RETURNING id. 请参阅https://en.wikipedia.org/wiki/Insert_(SQL)#Retrieving_the_key

您是否需要学习插入的 ID，以及您的 SQL 库是否支持 INSERT-RETURNING 命令 - 由您决定。

但是，当我进行 Google 搜索（它是 www.google.com）时，它带有许多关于C# Firebird Insert Returniung许多不同 C# SQL 库的链接，而且只有您才能知道您使用的是哪一个。对于来自不同库的几个示例：

• http://www.ibprovider.com/eng/documentation/firebird_21_adonet.html
• http://www.sql.ru/forum/actualutils.aspx?action=gotomsg&tid=720869&msg=8075816
• 从 Firebird db 表中检索最后一个 id
• Firebird 插入...返回 asp.net
• https://social.msdn.microsoft.com/Forums/en-US/e7099cfb-7809-460a-aae9-79a2bd703454/how-i-can-return-the-id-after-insert-a-record-into- a-database-firebird-25-with-linq?forum=adodotnetentityframework

等等

Answer 2

定义：

public const string stMAIN_TABLE_NAME = " OrgTable ";
public const string stDELETED_TABLE_NAME = "  BackupTable ";

public const string stFIELD_DEFINITIONS = " fstPriority VARCHAR(30)" + 
                                          ", fstInfo VARCHAR(100)" +
                                          ", fstDateCreated VARCHAR(30)" +
                                          ", fstDateModified VARCHAR(30)" +
                                          ", fiKeyID INTEGER GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY ";

public const string stFIELD_NAMES_NO_KEY_ID = " fstPriority" + 
                                              ", fstInfo" + 
                                              ", fstDateCreated" + 
                                              ", fstDateModified ";

public const string stFIELD_NAMES_KEY_ID = " fiKeyID ";

public const string stFIELD_NAMES = stFIELD_NAMES_NO_KEY_ID + ", " + stFIELD_NAMES_KEY_ID;

代码：

//------------------------------
static private bool boCreateDatabaseTables(string stPathFilename, 
                                           string stUserID, 
                                           string stPassword, 
                                           List<string> liststTableNames, 
                                           List<string> liststFieldDefinitions) 
{
  bool boErrorFlag = false;
  int iTablesCount = liststTableNames.Count();
  string stOpenConn = new FbConnectionStringBuilder {
    Database = stPathFilename,
    UserID = stUserID,
    Password = stPassword,
    ServerType = FbServerType.Embedded,
    ClientLibrary = stCLIENT_LIBRARY
    }.ToString();
  using (FbConnection fbConn = new FbConnection(stOpenConn)) {
    try {
      fbConn.Open();

      FbTransaction fbTransaction = fbConn.BeginTransaction();
      for (int ii = 0; ii < iTablesCount; ii++) {
        string stSql = "CREATE TABLE " + liststTableNames[ii] + "( " + liststFieldDefinitions[ii] + ")";
        FbCommand fbCmd = new FbCommand(stSql, fbConn, fbTransaction);
        fbCmd.ExecuteNonQuery();
      }
      fbTransaction.Commit();
    }
    catch (Exception ex) {
      boErrorFlag = true;
      MessageBox.Show("catch ... GlobalsFirebird ... boCreateDatabaseTables ... " + ex.Message);
    }
}
return boErrorFlag;
}//boCreateDatabaseTables
//------------------------------
//------------------------------
static public bool boAddRow(string stPathFilename,
                            string stUserID,
                            string stPassword,
                            string stTableName,
                            string stFieldNamesNoKeyId,
                            string stFieldNamesKeyId,
                            List<string> liststFieldValuesNoKeyId) 
{
  bool boErrorFlag = false;
  string stOpenConn = new FbConnectionStringBuilder {
    Database = stPathFilename,
    UserID = stUserID,
    Password = stPassword,
    ServerType = FbServerType.Embedded,
    ClientLibrary = stCLIENT_LIBRARY
  }.ToString();

  using(FbConnection fbConn = new FbConnection(stOpenConn)) {
    fbConn.Open();
    try {
      string stValuesPlaceHolder = "@p0";
      for (int iii = 1; iii < liststFieldValuesNoKeyId.Count; iii++)
        stValuesPlaceHolder += ", @p" + (iii).ToString();
      FbTransaction fbTransaction = fbConn.BeginTransaction();
      string stCmd = "INSERT INTO " + stTableName + "(" + stFieldNamesNoKeyId + ") VALUES ( " + stValuesPlaceHolder + " ) RETURNING  " + stFieldNamesKeyId;
      FbCommand fbCmd = new FbCommand(stCmd, fbConn, fbTransaction);

      for (int iii = 0; iii < liststFieldValuesNoKeyId.Count; iii++) {
        string stPlaceHolder = "@p" + (iii).ToString();
        string stValue = liststFieldValuesNoKeyId[iii];
        fbCmd.Parameters.AddWithValue(stPlaceHolder, stValue);
      }
      fbCmd.Parameters.Add(new FbParameter() { Direction = System.Data.ParameterDirection.Output });
      fbCmd.ExecuteNonQuery();
      fbTransaction.Commit();
    }
    catch (Exception ex) {
      boErrorFlag = true;
      MessageBox.Show("catch ... GlobalsFirebird ... boAddRow ... " + ex.Message);
    }
  }
  return boErrorFlag;
}//boAddRow
//------------------------------