I want to insert null value in database if that variable is blank, but in command string it insert blank instead of null. So give error.

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I want to insert null value in database if that variable is blank, but in command string it insert blank instead of null. so give error "

Incorrect syntax near ','

". i am posting my code with Command string and error message in following. thanks in advance.

What I have tried:

for (int i = 0; i < datProjectCostDetail.Rows.Count; i++)
{
int? PageSizeID;
double? RatePerPage;
int? TotalPage;
if (datProjectCostDetail.Rows[i][6].ToString() == "")
{PageSizeID = null; }
else
{PageSizeID = (int) datProjectCostDetail.Rows[i][6]; }

if (datProjectCostDetail.Rows[i][9].ToString() == "")
{ RatePerPage = null; }
else
{ RatePerPage = (double) datProjectCostDetail.Rows[i][9]; }

if (datProjectCostDetail.Rows[i][10].ToString() == "")
{ TotalPage = null; }
else
{ TotalPage = (int) datProjectCostDetail.Rows[i][10]; }

cmd = new SqlCommand("Insert into TblProjectCostDetail values(" + ProjectID + ", " + datProjectCostDetail.Rows[i][0] + ", '" + datProjectCostDetail.Rows[i][2].ToString() + "', " + datProjectCostDetail.Rows[i][3] + ", '" + datProjectCostDetail.Rows[i][5].ToString() + "', " + PageSizeID + ", '" + datProjectCostDetail.Rows[i][8].ToString() + "', " + RatePerPage + ", " + TotalPage + ", '" + datProjectCostDetail.Rows[i][11].ToString() + "', " + datProjectCostDetail.Rows[i][12] + " )", con, trans);
               cmd.ExecuteNonQuery();

OutPut of Command Query
Insert into TblProjectCostDetail values(1, 1, '09/Sep/2016', 1, 'Miscellaneous Payment', , '', , , 'Discount', 600 )

Posted 20-Sep-16 22:43pm

kantagrawal

Updated 21-Sep-16 0:58am

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3 solutions

Solution 3

Pass DBNull.Value to database if string is empty. You can simply check that by string.IsNullOrWhiteSpace

Posted 21-Sep-16 0:58am

lavikgupta

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Karthik_Mahalingam · Accepted Answer · 2016-09-20T23:01:00

Dont concatenate the sql statements, it will lead to sql injection[^] attacks
always use Parameterized queries to prevent SQL Injection Attacks in SQL Server[^]
by doing so, it will be simplify your sql statement and dont need to bother on the datatype formats

try like this

cmd = new SqlCommand("Insert into TblProjectCostDetail values(@col1,@col2,@col3,...colN)", con, trans);
         cmd.Parameters.Add("@col1", ProjectID);
         cmd.Parameters.Add("@col2", datProjectCostDetail.Rows[i][0]);
         cmd.Parameters.Add("@col3",datProjectCostDetail.Rows[i][2]);
         .
         .
         .
         cmd.Parameters.Add("@colN", datProjectCostDetail.Rows[i][12].ToString());
         cmd.ExecuteNonQuery();

use this is insert null values when it is String.Empty

string value = string.IsNullOrWhiteSpace(datProjectCostDetail.Rows[i][0].ToString()) ? null : datProjectCostDetail.Rows[i][0].ToString();

OriginalGriff · Accepted Answer · 2016-09-20T22:55:00

Solution 1

Never concatenate strings to build a SQL command. It leaves you wide open to accidental or deliberate SQL Injection attack which can destroy your entire database. Use Parametrized queries instead.
The chances are that will both protect your DB, and cure your problem.

Posted 20-Sep-16 22:55pm

OriginalGriff