having problem in retrieving primary key

[shamaila]

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.ExecuteRea der();
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(strQ uery1, conn);

commm.ExecuteNo nQuery();


but it is goiving an error on insert atement that
"Use of unassigned local variable 'i' "

[r035198x]

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.ExecuteRea der();
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(strQ uery1, conn);

commm.ExecuteNo nQuery();


but it is goiving an error on insert atement that
"Use of unassigned local variable 'i' "

Look at your code. You defined i inside the if block but you are trying to access it outside that if block.

[shamaila]

Look at your code. You defined i inside the if block but you are trying to access it outside that if block.

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??/

[dip_developer]

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.ExecuteRea der();
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(strQ uery1, conn);

commm.ExecuteNo nQuery();


but it is goiving an error on insert atement that
"Use of unassigned local variable 'i' "

you are declaring i globally....... like
[CODE=css] int i;[/CODE]

ok????......... .....
now in the if block you are writing

[CODE=css]
if (dr.Read())
{
i = Convert.ToInt32 (dr.GetValue(1) );

}
[/CODE]

then no problem will be there....please check your code.....
whether you are again writing

int i=Convert.ToInt 32(dr.GetValue( 1)); in the if block.....
hope u understand..... ......

[shamaila]

you are declaring i globally....... like
[CODE=css] int i;[/CODE]

ok????......... .....
now in the if block you are writing

[CODE=css]
if (dr.Read())
{
i = Convert.ToInt32 (dr.GetValue(1) );

}
[/CODE]

then no problem will be there....please check your code.....
whether you are again writing

int i=Convert.ToInt 32(dr.GetValue( 1)); in the if block.....
hope u understand..... ......

yea i have again checked it ..i did it the same way but still getting the same error..

[r035198x]

yea i have again checked it ..i did it the same way but still getting the same error..

Can you post the code that you have now and the error message you are getting?

[shamaila]

Can you post the code that you have now and the error message you are getting?

[CODE=css] string strQuery = "";
string strQuery1 = "";
string id;
int i;

//******insert data into parent table**********

strQuery = "INSERT INTO call_history(ph _num,c_date)VAL UES('" + textBox1.Text + "','" + textBox3.Text + "')";

SqlCommand com = new SqlCommand(strQ uery, conn);
conn.Open();
com.ExecuteNonQ uery();


//*** retrieve parent table's primary key *****

id = "SELECT MAX(c_id) FROM call_history";
SqlCommand com1 = new SqlCommand(id, conn);
SqlDataReader dr = com1.ExecuteRea der();
if (dr.Read())
{
i = Convert.ToInt32 (dr.GetValue(1) );

}

//************* insert data into child table

strQuery1 = "INSERT INTO call_log(c_id,c _add)VALUES("+ i +",'"+textBox2. Text +"')";

SqlCommand commm = new SqlCommand(strQ uery1, conn);

commm.ExecuteNo nQuery();[/CODE]

and the error msg is
Use of unassigned local variable 'i'

[r035198x]

[CODE=css] string strQuery = "";
string strQuery1 = "";
string id;
int i;

//******insert data into parent table**********

strQuery = "INSERT INTO call_history(ph _num,c_date)VAL UES('" + textBox1.Text + "','" + textBox3.Text + "')";

SqlCommand com = new SqlCommand(strQ uery, conn);
conn.Open();
com.ExecuteNonQ uery();


//*** retrieve parent table's primary key *****

id = "SELECT MAX(c_id) FROM call_history";
SqlCommand com1 = new SqlCommand(id, conn);
SqlDataReader dr = com1.ExecuteRea der();
if (dr.Read())
{
i = Convert.ToInt32 (dr.GetValue(1) );

}

//************* insert data into child table

strQuery1 = "INSERT INTO call_log(c_id,c _add)VALUES("+ i +",'"+textBox2. Text +"')";

SqlCommand commm = new SqlCommand(strQ uery1, conn);

commm.ExecuteNo nQuery();[/CODE]

and the error msg is
Use of unassigned local variable 'i'

The if test may fail so the compiler needs to know that i is definitely assigned before being used in

[CODE=css] strQuery1 = "INSERT INTO call_log(c_id,c _add)VALUES("+ i +",'"+textBox2. Text +"')";[/CODE]

So give it a default value when you declare it like -1 for example.

[dip_developer]

The if test may fail so the compiler needs to know that i is definitely assigned before being used in

[CODE=css] strQuery1 = "INSERT INTO call_log(c_id,c _add)VALUES("+ i +",'"+textBox2. Text +"')";[/CODE]

So give it a default value when you declare it like -1 for example.

exactly so........

Write
int i=0; when declaring it.....because your query may not return a value.......

[shamaila]

The if test may fail so the compiler needs to know that i is definitely assigned before being used in

[CODE=css] strQuery1 = "INSERT INTO call_log(c_id,c _add)VALUES("+ i +",'"+textBox2. Text +"')";[/CODE]

So give it a default value when you declare it like -1 for example.

now i tried doing it without if statement
as simply writing;
i = Convert.ToInt32 (dr.GetValue(1) );


but following error occured
Invalid attempt to read when no data is present.

[r035198x]

now i tried doing it without if statement
as simply writing;
i = Convert.ToInt32 (dr.GetValue(1) );


but following error occured
Invalid attempt to read when no data is present.

Why are you removing the if ?
Its job is to guard you against that error that you're getting now.

[shamaila]

Why are you removing the if ?
Its job is to guard you against that error that you're getting now.

but is not working with that...

[radcaesar]

Declare the variable immediately after your class declaration.

Initialize it like int i=0 or Check for nullability when you cast the variable.

:)

[r035198x]

but is not working with that...

The if is not what's making it not work. Read* my reply above again.
When you declare i at the top there, initialize it to something and leave the if there.


*Reading: An extinct, ancient art which students used to obtain information.

[shamaila]

Declare the variable immediately after your class declaration.

Initialize it like int i=0 or Check for nullability when you cast the variable.

:)

i tried it... there was no error on debugging but when i tried inserting values and clicked on save button the following exception was handled
Index was outside the bounds of the array.