Question

我想插入数据库新客户。要做到这一点，我必须放入表CLIENT FirstName，LastName，Postcode。对于第二个表CLIENTGROUP，我必须放置客户组，如访客或VIP。第一个表ID是第二个外键。

当我在CLIENT中添加新客户时，ID会自动增加。如何在CLIENTGROUP中进行更新id的查询？我将不得不加入两个查询

        var connection = OpenConnection();
        var command = connection.CreateCommand();
        command.CommandText = "insert into Klient(FirstName,LastName,Postcode) values (@FirstName, @LastName, @Postcode)";
        AddParameterString(command, "@FirstName", model.FirstName);
        AddParameterString(command, "@LastName", model.LastName);
        AddParameterDecimal(command, "@Turnover", model.Postcode);

        command.ExecuteNonQuery();

        command.CommandText = "insert into ClientGroup (ClientGroup) values (@ClientGroup)";
        AddParameterString(command, "@ClientGroup", model.ClienGroup);"                        
        command.ExecuteNonQuery();

但我根本不知道如何。

Answer 1

将SELECT SCOPE_IDENTITY()添加到第一个插入查询中，这将为您提供插入客户的ID。在c＃端使用ExecuteScalar方法（如果使用ADO.NET）。查询：

INSERT INTO Customer (/*...*/) VALUES (/*...*/)
SELECT SCOPE_IDENTITY()

C＃：

var connection = OpenConnection();
var command = connection.CreateCommand();
command.CommandText = @"
    insert into Klient(FirstName,LastName,Postcode) values (@FirstName, @LastName, @Postcode)
    SELECT SCOPE_IDENTITY()";

AddParameterString(command, "@FirstName", model.FirstName);
AddParameterString(command, "@LastName", model.LastName);
AddParameterDecimal(command, "@Turnover", model.Postcode);

int customerId = (int) command.ExecuteNonQuery();

// ...use customerId in the second insert

您也可以考虑使用事务包装这两个插入查询。

Answer 2

您的代码将如下所示。假设ClientId是主键列的名称。同时为外键设置自动增量（在ClientGroup表中）。

    var connection = OpenConnection();
    var command = connection.CreateCommand();
    command.CommandText = "insert into Klient(FirstName,LastName,Postcode) values (@FirstName, @LastName, @Postcode) Select Ident_Current('Klient')";
    AddParameterString(command, "@FirstName", model.FirstName);
    AddParameterString(command, "@LastName", model.LastName);
    AddParameterDecimal(command, "@Turnover", model.Postcode);

    int foreignKey = command.ExecuteScaler();

    command.CommandText = "insert into ClientGroup (ClientId,ClientGroup) values (@ClientId, @ClientGroup)";
    AddParameterString(command, "@ClientId", foreignKey);
    AddParameterString(command, "@ClientGroup", model.ClienGroup);                        
    command.ExecuteNonQuery();

如何使用外键更新两个表

2 个答案: