在检索主键时遇到问题 [英] having problem in retrieving primary key
问题描述
我想检索父表的主键然后将此密钥发送到子表，因为它们具有一对一的关系
我已经编写了代码
string id =" SELECT MAX（c_id）FROM call_history" ;;
SqlCommand com1 = new SqlCommand（id，conn）;
SqlDataReader dr = com1。 ExecuteReader（）;
if（dr.Read（））
{
int i = Convert.ToInt32（dr.GetValue（1） ）;
}
strQuery1 =" INSERT INTO call_log（c_id，c_add）VALUES（" + i +"，' '" + textBox2.Text +"''）" ;;
SqlCommand commm = new SqlCommand（strQuery1，conn）;
commm.ExecuteNonQuery（）;
但它在插入atement时出错了
"使用未分配的局部变量''我''"
i want to retrieve primary key of parent table and then send this key to child table,as they have one-one relationship
i''ve written code
string id = "SELECT MAX(c_id) FROM call_history";
SqlCommand com1 = new SqlCommand(id, conn);
SqlDataReader dr = com1.ExecuteReader();
if (dr.Read())
{
int i = Convert.ToInt32(dr.GetValue(1));
}
strQuery1 = "INSERT INTO call_log(c_id,c_add)VALUES("+ i +",''"+textBox2.Text +"'')";
SqlCommand commm = new SqlCommand(strQuery1, conn);
commm.ExecuteNonQuery();
but it is goiving an error on insert atement that
"Use of unassigned local variable ''i'' "
推荐答案
i想要检索父表的主键，然后将此密钥发送到子表，因为它们具有一对一的关系
我已经编写了代码
string id =" SELECT MAX（c_id）FROM call_history" ;;
SqlCommand com1 = new SqlCommand（id ，conn）;
SqlDataReader dr = com1.ExecuteReader（）;
if（dr.Read（））
{
int i = Convert.ToInt32（dr.GetValue（1））;
}
strQuery1 =" INSERT INTO call_log（c_id，c_add）VALUES（" + i +"，''" + textBox2.Text +"''）" ;;
SqlCommand commm = new SqlCommand （strQuery1，conn）;
commm.ExecuteNonQuery（）;
但它在插入atement时出错了
"使用未分配的局部变量''i''
i want to retrieve primary key of parent table and then send this key to child table,as they have one-one relationship
i''ve written code
string id = "SELECT MAX(c_id) FROM call_history";
SqlCommand com1 = new SqlCommand(id, conn);
SqlDataReader dr = com1.ExecuteReader();
if (dr.Read())
{
int i = Convert.ToInt32(dr.GetValue(1));
}
strQuery1 = "INSERT INTO call_log(c_id,c_add)VALUES("+ i +",''"+textBox2.Text +"'')";
SqlCommand commm = new SqlCommand(strQuery1, conn);
commm.ExecuteNonQuery();
but it is goiving an error on insert atement that
"Use of unassigned local variable ''i'' "
查看你的代码。你在if块中定义了i，但是你试图在if块之外访问它。
Look at your code. You defined i inside the if block but you are trying to access it outside that if block.
查看你的代码。你在if块中定义了i，但是你试图在if块之外访问它。
Look at your code. You defined i inside the if block but you are trying to access it outside that if block.
这次我定义了我的全局，但仍然有同样的问题......插入语句有什么问题吗？
有我写了sql命令rite ?? /
this time i defined i globaly but still having the same problem...is there any problem in the insert statement??
have i written the sql command rite??/
i想要检索父表的主键，然后将此密钥发送到子表，如他们有一对一的关系
我写了代码
string id =" SELECT MAX（c_id）FROM call_history" ;;
SqlCommand com1 = new SqlCommand（id，conn）;
SqlDataReader dr = com1.ExecuteReader（）;
if（dr.Read（））
{
int i = Convert.ToInt32（dr.GetValue（1））;
}
strQuery1 =" INSERT INTO call_log（c_id，c_add）VALUES（" + i +"，''" + textBox2.Text +"''）" ;;
SqlCommand commm = new SqlCommand（strQuery1，conn）;
commm.ExecuteNonQuery（）;
但是它是插入atement的错误
使用未分配的局部变量''我''
i want to retrieve primary key of parent table and then send this key to child table,as they have one-one relationship
i''ve written code
string id = "SELECT MAX(c_id) FROM call_history";
SqlCommand com1 = new SqlCommand(id, conn);
SqlDataReader dr = com1.ExecuteReader();
if (dr.Read())
{
int i = Convert.ToInt32(dr.GetValue(1));
}
strQuery1 = "INSERT INTO call_log(c_id,c_add)VALUES("+ i +",''"+textBox2.Text +"'')";
SqlCommand commm = new SqlCommand(strQuery1, conn);
commm.ExecuteNonQuery();
but it is goiving an error on insert atement that
"Use of unassigned local variable ''i'' "
你在全球范围内宣布.......赞
you are declaring i globally.......like
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