I am creating a simple project on c#.net. I want to put the AutoNo textbox in my program. I have put but it is not working. it shown the error while ran program error said that
Value cannot be null Parameter name: Stringmscorlib
Code what I tried I attached below
public void Load()
{
SqlConnection Con = new SqlConnection("Data Source=.;Initial Catalog=test1;Persist Security Info=True;User ID=sa;Password=admin123");
Con.Open();
cmd = new SqlCommand("select id from records", Con);
Data = cmd.ExecuteReader();
while (Data.Read() != false)
{
auto = int.Parse(Data[0].ToString());
}
try
{
int newid = auto;
int id = newid + 1;
this.textBox1.Text = "S00" + id.ToString();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message + ex.Source);
}
Data.Close();
}
}
There are two problems I can see here; the first would be: what if there are zero rows? what is auto then? is it null? then int.Parse(null) will fail. You don't actually show where auto is declared, which makes this bit a little hard to intuit about.
The other possibility is here:
auto = Data.GetString(0);
in which case: this is simply a null database value. Check for that, and handle it:
if (Data.IsDBNull(0))
{ ... do whatever; perhaps just "continue" }
else
{
auto = Data.IsDBNull(0);
// and process it, etc
}
But frankly, you're making life hard for yourself here; here's the same thing with a tool like Dapper:
using (var conn= new SqlConnection("...whatever..."))
{
// here we're asserting *exactly* zero or one row
string auto = conn.QuerySingleOrDefault<string>("select id from records");
if (auto == null)
{ ... do something else? ... }
else
{
var newid= int.Parse(auto);
}
}
Note: your query could currently return any number of rows; since the code only processes the last value, I suggest that the SQL needs fixing; perhaps MAX, MIN, or TOP 1 with an ORDER BY clause; i.e. something like select MAX(id) as [id] from records. Note, however, that this sounds like a scenario where you should probably have used SCOPE_IDENTITY() in some query that added or inserted the value. And an id should very rarely be a string.
Parse method is not able to handle null value. Assuming auto is variable name.
instead of this
int newid = Int32.Parse(auto);
use something like below
int newid=0;
int.TryParse(auto, out newid);
I'm trying to update a Database table and getting the error
"MySql.Data.MySqlClient.MySqlException: 'You have an error in your SQL
syntax; check the manual that corresponds to your MySQL server version
for the right syntax to use near 'group='superadmin' WHERE
identifier='steam:steam:1100001098b5888'' at line 1'"
// Creates query to run
public void UpdateInfo(String jobTitle, int jobGrade, String adminLevel, String identifier) {
// Opens the database connection if it's not already open
if (!(databaseConnected)) {
openConnection();
}
// Creates query to run
String query = "UPDATE " + table + " SET job=#jobTitle, job_grade=#jobGrade, group=#adminLevel WHERE identifier=#identifier";
// Makes a new command
MySqlCommand cmd = new MySqlCommand(query, connection);
// Replaces the # placeholders with actual variables
cmd.Parameters.AddWithValue("#jobTitle", jobTitle);
cmd.Parameters.AddWithValue("#jobGrade", jobGrade);
cmd.Parameters.AddWithValue("#adminLevel", adminLevel);
cmd.Parameters.AddWithValue("#identifier", identifier);
// Executes it and if it's...
if (cmd.ExecuteNonQuery() > 0) {
// Successful
MessageBox.Show("Successfully updated information");
closeConnection();
return;
} else {
// Not successful
MessageBox.Show("Error with updating information!");
// Closes the connection again to prevent leaks
closeConnection();
return;
}
}
I tried your query on https://sqltest.net/ and noticed it highlighted "group" when I tried to create the table. I'm wondering if the problem might be the usage of "group" as a column name since it's a reserved word.
Is it possible to try renaming the column to group_level or adding back ticks around 'group' or "group" and seeing if that works?
So for example
'group'=#grouplevel
I found this thread and this thread on renaming the column where they had issues with "group" as a column name. Adding backticks seemed to solve both problems.
EDIT: As per OP, double quotes (") solved the issue instead of single. Edited answer to include.
Try change query like this
String query = "UPDATE " + table + " SET job='#jobTitle', job_grade=#jobGrade, group='#adminLevel' WHERE identifier='#identifier'";
if you input String value with query, you need to use 'this' for work
I hope this will work for you.
if not, you can use String.Format for that like this.
String Query = String.Format("Update `{0}` Set job='{1}', job_grade={2}, group='{3}' Where identifier='{4}'", table, jobTitle, jobGrade, adminLevel, identifier);
I am running data.bat file with the following lines:
Rem Tis batch file will populate tables
cd\program files\Microsoft SQL Server\MSSQL
osql -U sa -P Password -d MyBusiness -i c:\data.sql
The contents of the data.sql file is:
insert Customers
(CustomerID, CompanyName, Phone)
Values('101','Southwinds','19126602729')
There are 8 more similar lines for adding records.
When I run this with start > run > cmd > c:\data.bat, I get this error message:
1>2>3>4>5>....<1 row affected>
Msg 8152, Level 16, State 4, Server SP1001, Line 1
string or binary data would be truncated.
<1 row affected>
<1 row affected>
<1 row affected>
<1 row affected>
<1 row affected>
<1 row affected>
Also, I am a newbie obviously, but what do Level #, and state # mean, and how do I look up error messages such as the one above: 8152?
From #gmmastros's answer
Whenever you see the message....
string or binary data would be truncated
Think to yourself... The field is NOT big enough to hold my data.
Check the table structure for the customers table. I think you'll find that the length of one or more fields is NOT big enough to hold the data you are trying to insert. For example, if the Phone field is a varchar(8) field, and you try to put 11 characters in to it, you will get this error.
I had this issue although data length was shorter than the field length.
It turned out that the problem was having another log table (for audit trail), filled by a trigger on the main table, where the column size also had to be changed.
In one of the INSERT statements you are attempting to insert a too long string into a string (varchar or nvarchar) column.
If it's not obvious which INSERT is the offender by a mere look at the script, you could count the <1 row affected> lines that occur before the error message. The obtained number plus one gives you the statement number. In your case it seems to be the second INSERT that produces the error.
Just want to contribute with additional information: I had the same issue and it was because of the field wasn't big enough for the incoming data and this thread helped me to solve it (the top answer clarifies it all).
BUT it is very important to know what are the possible reasons that may cause it.
In my case i was creating the table with a field like this:
Select '' as Period, * From Transactions Into #NewTable
Therefore the field "Period" had a length of Zero and causing the Insert operations to fail. I changed it to "XXXXXX" that is the length of the incoming data and it now worked properly (because field now had a lentgh of 6).
I hope this help anyone with same issue :)
Some of your data cannot fit into your database column (small). It is not easy to find what is wrong. If you use C# and Linq2Sql, you can list the field which would be truncated:
First create helper class:
public class SqlTruncationExceptionWithDetails : ArgumentOutOfRangeException
{
public SqlTruncationExceptionWithDetails(System.Data.SqlClient.SqlException inner, DataContext context)
: base(inner.Message + " " + GetSqlTruncationExceptionWithDetailsString(context))
{
}
/// <summary>
/// PArt of code from following link
/// http://stackoverflow.com/questions/3666954/string-or-binary-data-would-be-truncated-linq-exception-cant-find-which-fiel
/// </summary>
/// <param name="context"></param>
/// <returns></returns>
static string GetSqlTruncationExceptionWithDetailsString(DataContext context)
{
StringBuilder sb = new StringBuilder();
foreach (object update in context.GetChangeSet().Updates)
{
FindLongStrings(update, sb);
}
foreach (object insert in context.GetChangeSet().Inserts)
{
FindLongStrings(insert, sb);
}
return sb.ToString();
}
public static void FindLongStrings(object testObject, StringBuilder sb)
{
foreach (var propInfo in testObject.GetType().GetProperties())
{
foreach (System.Data.Linq.Mapping.ColumnAttribute attribute in propInfo.GetCustomAttributes(typeof(System.Data.Linq.Mapping.ColumnAttribute), true))
{
if (attribute.DbType.ToLower().Contains("varchar"))
{
string dbType = attribute.DbType.ToLower();
int numberStartIndex = dbType.IndexOf("varchar(") + 8;
int numberEndIndex = dbType.IndexOf(")", numberStartIndex);
string lengthString = dbType.Substring(numberStartIndex, (numberEndIndex - numberStartIndex));
int maxLength = 0;
int.TryParse(lengthString, out maxLength);
string currentValue = (string)propInfo.GetValue(testObject, null);
if (!string.IsNullOrEmpty(currentValue) && maxLength != 0 && currentValue.Length > maxLength)
{
//string is too long
sb.AppendLine(testObject.GetType().Name + "." + propInfo.Name + " " + currentValue + " Max: " + maxLength);
}
}
}
}
}
}
Then prepare the wrapper for SubmitChanges:
public static class DataContextExtensions
{
public static void SubmitChangesWithDetailException(this DataContext dataContext)
{
//http://stackoverflow.com/questions/3666954/string-or-binary-data-would-be-truncated-linq-exception-cant-find-which-fiel
try
{
//this can failed on data truncation
dataContext.SubmitChanges();
}
catch (SqlException sqlException) //when (sqlException.Message == "String or binary data would be truncated.")
{
if (sqlException.Message == "String or binary data would be truncated.") //only for EN windows - if you are running different window language, invoke the sqlException.getMessage on thread with EN culture
throw new SqlTruncationExceptionWithDetails(sqlException, dataContext);
else
throw;
}
}
}
Prepare global exception handler and log truncation details:
protected void Application_Error(object sender, EventArgs e)
{
Exception ex = Server.GetLastError();
string message = ex.Message;
//TODO - log to file
}
Finally use the code:
Datamodel.SubmitChangesWithDetailException();
Another situation in which you can get this error is the following:
I had the same error and the reason was that in an INSERT statement that received data from an UNION, the order of the columns was different from the original table. If you change the order in #table3 to a, b, c, you will fix the error.
select a, b, c into #table1
from #table0
insert into #table1
select a, b, c from #table2
union
select a, c, b from #table3
on sql server you can use SET ANSI_WARNINGS OFF like this:
using (SqlConnection conn = new SqlConnection("Data Source=XRAYGOAT\\SQLEXPRESS;Initial Catalog='Healthy Care';Integrated Security=True"))
{
conn.Open();
using (var trans = conn.BeginTransaction())
{
try
{
using cmd = new SqlCommand("", conn, trans))
{
cmd.CommandText = "SET ANSI_WARNINGS OFF";
cmd.ExecuteNonQuery();
cmd.CommandText = "YOUR INSERT HERE";
cmd.ExecuteNonQuery();
cmd.Parameters.Clear();
cmd.CommandText = "SET ANSI_WARNINGS ON";
cmd.ExecuteNonQuery();
trans.Commit();
}
}
catch (Exception)
{
trans.Rollback();
}
}
conn.Close();
}
I had the same issue. The length of my column was too short.
What you can do is either increase the length or shorten the text you want to put in the database.
Also had this problem occurring on the web application surface.
Eventually found out that the same error message comes from the SQL update statement in the specific table.
Finally then figured out that the column definition in the relating history table(s) did not map the original table column length of nvarchar types in some specific cases.
I had the same problem, even after increasing the size of the problematic columns in the table.
tl;dr: The length of the matching columns in corresponding Table Types may also need to be increased.
In my case, the error was coming from the Data Export service in Microsoft Dynamics CRM, which allows CRM data to be synced to an SQL Server DB or Azure SQL DB.
After a lengthy investigation, I concluded that the Data Export service must be using Table-Valued Parameters:
You can use table-valued parameters to send multiple rows of data to a Transact-SQL statement or a routine, such as a stored procedure or function, without creating a temporary table or many parameters.
As you can see in the documentation above, Table Types are used to create the data ingestion procedure:
CREATE TYPE LocationTableType AS TABLE (...);
CREATE PROCEDURE dbo.usp_InsertProductionLocation
#TVP LocationTableType READONLY
Unfortunately, there is no way to alter a Table Type, so it has to be dropped & recreated entirely. Since my table has over 300 fields (😱), I created a query to facilitate the creation of the corresponding Table Type based on the table's columns definition (just replace [table_name] with your table's name):
SELECT 'CREATE TYPE [table_name]Type AS TABLE (' + STRING_AGG(CAST(field AS VARCHAR(max)), ',' + CHAR(10)) + ');' AS create_type
FROM (
SELECT TOP 5000 COLUMN_NAME + ' ' + DATA_TYPE
+ IIF(CHARACTER_MAXIMUM_LENGTH IS NULL, '', CONCAT('(', IIF(CHARACTER_MAXIMUM_LENGTH = -1, 'max', CONCAT(CHARACTER_MAXIMUM_LENGTH,'')), ')'))
+ IIF(DATA_TYPE = 'decimal', CONCAT('(', NUMERIC_PRECISION, ',', NUMERIC_SCALE, ')'), '')
AS field
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = '[table_name]'
ORDER BY ORDINAL_POSITION) AS T;
After updating the Table Type, the Data Export service started functioning properly once again! :)
When I tried to execute my stored procedure I had the same problem because the size of the column that I need to add some data is shorter than the data I want to add.
You can increase the size of the column data type or reduce the length of your data.
A 2016/2017 update will show you the bad value and column.
A new trace flag will swap the old error for a new 2628 error and will print out the column and offending value. Traceflag 460 is available in the latest cumulative update for 2016 and 2017:
https://support.microsoft.com/en-sg/help/4468101/optional-replacement-for-string-or-binary-data-would-be-truncated
Just make sure that after you've installed the CU that you enable the trace flag, either globally/permanently on the server:
...or with DBCC TRACEON:
https://learn.microsoft.com/en-us/sql/t-sql/database-console-commands/dbcc-traceon-trace-flags-transact-sql?view=sql-server-ver15
Another situation, in which this error may occur is in
SQL Server Management Studio. If you have "text" or "ntext" fields in your table,
no matter what kind of field you are updating (for example bit or integer).
Seems that the Studio does not load entire "ntext" fields and also updates ALL fields instead of the modified one.
To solve the problem, exclude "text" or "ntext" fields from the query in Management Studio
This Error Comes only When any of your field length is greater than the field length specified in sql server database table structure.
To overcome this issue you have to reduce the length of the field Value .
Or to increase the length of database table field .
If someone is encountering this error in a C# application, I have created a simple way of finding offending fields by:
Getting the column width of all the columns of a table where we're trying to make this insert/ update. (I'm getting this info directly from the database.)
Comparing the column widths to the width of the values we're trying to insert/ update.
Assumptions/ Limitations:
The column names of the table in the database match with the C# entity fields. For eg: If you have a column like this in database:
You need to have your Entity with the same column name:
public class SomeTable
{
// Other fields
public string SourceData { get; set; }
}
You're inserting/ updating 1 entity at a time. It'll be clearer in the demo code below. (If you're doing bulk inserts/ updates, you might want to either modify it or use some other solution.)
Step 1:
Get the column width of all the columns directly from the database:
// For this, I took help from Microsoft docs website:
// https://learn.microsoft.com/en-us/dotnet/api/system.data.sqlclient.sqlconnection.getschema?view=netframework-4.7.2#System_Data_SqlClient_SqlConnection_GetSchema_System_String_System_String___
private static Dictionary<string, int> GetColumnSizesOfTableFromDatabase(string tableName, string connectionString)
{
var columnSizes = new Dictionary<string, int>();
using (var connection = new SqlConnection(connectionString))
{
// Connect to the database then retrieve the schema information.
connection.Open();
// You can specify the Catalog, Schema, Table Name, Column Name to get the specified column(s).
// You can use four restrictions for Column, so you should create a 4 members array.
String[] columnRestrictions = new String[4];
// For the array, 0-member represents Catalog; 1-member represents Schema;
// 2-member represents Table Name; 3-member represents Column Name.
// Now we specify the Table_Name and Column_Name of the columns what we want to get schema information.
columnRestrictions[2] = tableName;
DataTable allColumnsSchemaTable = connection.GetSchema("Columns", columnRestrictions);
foreach (DataRow row in allColumnsSchemaTable.Rows)
{
var columnName = row.Field<string>("COLUMN_NAME");
//var dataType = row.Field<string>("DATA_TYPE");
var characterMaxLength = row.Field<int?>("CHARACTER_MAXIMUM_LENGTH");
// I'm only capturing columns whose Datatype is "varchar" or "char", i.e. their CHARACTER_MAXIMUM_LENGTH won't be null.
if(characterMaxLength != null)
{
columnSizes.Add(columnName, characterMaxLength.Value);
}
}
connection.Close();
}
return columnSizes;
}
Step 2:
Compare the column widths with the width of the values we're trying to insert/ update:
public static Dictionary<string, string> FindLongBinaryOrStringFields<T>(T entity, string connectionString)
{
var tableName = typeof(T).Name;
Dictionary<string, string> longFields = new Dictionary<string, string>();
var objectProperties = GetProperties(entity);
//var fieldNames = objectProperties.Select(p => p.Name).ToList();
var actualDatabaseColumnSizes = GetColumnSizesOfTableFromDatabase(tableName, connectionString);
foreach (var dbColumn in actualDatabaseColumnSizes)
{
var maxLengthOfThisColumn = dbColumn.Value;
var currentValueOfThisField = objectProperties.Where(f => f.Name == dbColumn.Key).First()?.GetValue(entity, null)?.ToString();
if (!string.IsNullOrEmpty(currentValueOfThisField) && currentValueOfThisField.Length > maxLengthOfThisColumn)
{
longFields.Add(dbColumn.Key, $"'{dbColumn.Key}' column cannot take the value of '{currentValueOfThisField}' because the max length it can take is {maxLengthOfThisColumn}.");
}
}
return longFields;
}
public static List<PropertyInfo> GetProperties<T>(T entity)
{
//The DeclaredOnly flag makes sure you only get properties of the object, not from the classes it derives from.
var properties = entity.GetType()
.GetProperties(System.Reflection.BindingFlags.Public
| System.Reflection.BindingFlags.Instance
| System.Reflection.BindingFlags.DeclaredOnly)
.ToList();
return properties;
}
Demo:
Let's say we're trying to insert someTableEntity of SomeTable class that is modeled in our app like so:
public class SomeTable
{
[Key]
public long TicketID { get; set; }
public string SourceData { get; set; }
}
And it's inside our SomeDbContext like so:
public class SomeDbContext : DbContext
{
public DbSet<SomeTable> SomeTables { get; set; }
}
This table in Db has SourceData field as varchar(16) like so:
Now we'll try to insert value that is longer than 16 characters into this field and capture this information:
public void SaveSomeTableEntity()
{
var connectionString = "server=SERVER_NAME;database=DB_NAME;User ID=SOME_ID;Password=SOME_PASSWORD;Connection Timeout=200";
using (var context = new SomeDbContext(connectionString))
{
var someTableEntity = new SomeTable()
{
SourceData = "Blah-Blah-Blah-Blah-Blah-Blah"
};
context.SomeTables.Add(someTableEntity);
try
{
context.SaveChanges();
}
catch (Exception ex)
{
if (ex.GetBaseException().Message == "String or binary data would be truncated.\r\nThe statement has been terminated.")
{
var badFieldsReport = "";
List<string> badFields = new List<string>();
// YOU GOT YOUR FIELDS RIGHT HERE:
var longFields = FindLongBinaryOrStringFields(someTableEntity, connectionString);
foreach (var longField in longFields)
{
badFields.Add(longField.Key);
badFieldsReport += longField.Value + "\n";
}
}
else
throw;
}
}
}
The badFieldsReport will have this value:
'SourceData' column cannot take the value of
'Blah-Blah-Blah-Blah-Blah-Blah' because the max length it can take is
16.
Kevin Pope's comment under the accepted answer was what I needed.
The problem, in my case, was that I had triggers defined on my table that would insert update/insert transactions into an audit table, but the audit table had a data type mismatch where a column with VARCHAR(MAX) in the original table was stored as VARCHAR(1) in the audit table, so my triggers were failing when I would insert anything greater than VARCHAR(1) in the original table column and I would get this error message.
I used a different tactic, fields that are allocated 8K in some places. Here only about 50/100 are used.
declare #NVPN_list as table
nvpn varchar(50)
,nvpn_revision varchar(5)
,nvpn_iteration INT
,mpn_lifecycle varchar(30)
,mfr varchar(100)
,mpn varchar(50)
,mpn_revision varchar(5)
,mpn_iteration INT
-- ...
) INSERT INTO #NVPN_LIST
SELECT left(nvpn ,50) as nvpn
,left(nvpn_revision ,10) as nvpn_revision
,nvpn_iteration
,left(mpn_lifecycle ,30)
,left(mfr ,100)
,left(mpn ,50)
,left(mpn_revision ,5)
,mpn_iteration
,left(mfr_order_num ,50)
FROM [DASHBOARD].[dbo].[mpnAttributes] (NOLOCK) mpna
I wanted speed, since I have 1M total records, and load 28K of them.
This error may be due to less field size than your entered data.
For e.g. if you have data type nvarchar(7) and if your value is 'aaaaddddf' then error is shown as:
string or binary data would be truncated
You simply can't beat SQL Server on this.
You can insert into a new table like this:
select foo, bar
into tmp_new_table_to_dispose_later
from my_table
and compare the table definition with the real table you want to insert the data into.
Sometime it's helpful sometimes it's not.
If you try inserting in the final/real table from that temporary table it may just work (due to data conversion working differently than SSMS for example).
Another alternative is to insert the data in chunks, instead of inserting everything immediately you insert with top 1000 and you repeat the process, till you find a chunk with an error. At least you have better visibility on what's not fitting into the table.
I am trying to add some record to ACCESS file ,as you can see here :
string strconnection = #"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=AccessTemp.mdb";
private void InsertSellItems(List<TTMSModel> lstttms )
{
try
{
foreach (TTMSModel t in lstttms)
{
if (t.TypeMember == "حقیقی") t.TypeMember = "1";
else
{
t.TypeMember = "2";
}
OleDbConnection objconnection = new OleDbConnection(strconnection);
OleDbCommand objcommand = new OleDbCommand("INSERT INTO Foroush_Detail" +
"(KalaKhadamatName,KalaCode,BargashtType,Price,MaliatArzeshAfzoodeh,AvarezArzeshAfzoodeh,HCKharidarTypeCode,KharidarPostCode,KharidarPerCityCode,KharidarTell,KharidarAddress,KharidarName,KharidarLastNameSherkatName,KharidarEconomicNO,KharidarNationalCode,HCKharidarType1Code,CityCode,stateCode,IsSent,Sarjam)" +
"VALUES('فروش'," +"'0'"+",'0','"+t.PriceAmount+"','"+t.MayorAmount+"','"+t.TaxAmount+"','"+t.TypeMember+"','"+t.ZipCode+"','"+t.City+"','"+t.PhoneNumber+"','"+t.Address+"','"+t.Name+"','"+t.Name+"','"+t.EconomicNumber+"','"+t.IntNumber+"','2','"+t.City+"','"+t.Province+"','0','0')",
objconnection);
objconnection.Open();
objcommand.ExecuteNonQuery();
objconnection.Close();
}
}
catch (OleDbException a)
{
MessageBox.Show(a.Message);
}
}
I fetched the data from SQL server 2012.but after executing this query i got this error:
the field is too small to accept the amount of data you attempted to add access 2010.
The table structure is like this :
Best regards
For BargashtType column that is declared as Yes/No type, you are trying to insert فروش .Which is invalid, as the field will accept only 0 or 1 i.e. true or false.
It appears to me you are passing ever value in the query as a string, depite the fact some of the fields are numbers:
'"+t.City+"','"+t.Province+"'
Both of these values have a single quote around them, meaning they are strings, yet the two fields are Numbers.
That means you're leaving Access to do the conversion, you might want to try passing them as numeric values and see if that resolves the problem
I'm working on some code to try and get my array that's entered by the user to connect and send to SQL Server 2012. I've been told to use all of these commands to connect to the database.
One of my issues is that I've been looking through Stack Overflow and everyone suggests using parameters instead of concatenating to avoid SQL injection, but this is for my class and we are only 2 weeks into C# so I don't think he's going to like it if I use parameters.
I think my try catch is wrong, the top half is filled with red lines and how do you use the INSERT command with a for loop?
protected void btnDisplay_Click(object sender, EventArgs e)
{
//try
//{
// System.Data.SqlClient.SqlConnection varname1 = new System.Data.SqlClient.SqlConnection();
// varname1 = "server = LOCALHOST"; Database = Lab1; Trusted_connection = yes;
// varname1.Open();
// System.Data.SqlClient.SqlCommand cmd = new System.Data.SqlClient.SqlCommand();
// cmd.Connection = conn;
// cmd.CommandText = "Delete From Student";
// cmd.ExecuteNonQuery();
//
string sql = null;
for(int i=0; counter1 >= i; i++)
{
sql += "INSERT into Student VALUES(" + StudentId + Name + Address);
}
varname1.Close();
//}
catch (SqlException ex)
{
MessageBox.Show("Database failed" + ex.Message);
}
}
So, there are quite a few problems with this code. It might be best to spend another hour on it or so, then post any specific questions you can't figure out. Let me give you a few quick pointers though.
You have a catch() block, but the matching try block is commented out. This will result in a compiler error. It looks like you were just debugging some stuff, so no big deal. However, it's usually wise to post the actual code you're trying to run.
You're initializing a string to null, but you're concatenating on to the end. This will result in a runtime error. You should initialize your string to String.Empty instead. Also, look into the StringBuilder class if you're doing large amounts of string concatenation, as it's much faster.
You're (in theory) building a SQL string, but never actually running it anywhere. Nor do you return the value to anything that could run it.
Your INSERT statement isn't even valid. You don't have a matching end ) in the INSERT statement, and you have a rogue ) after your variables, which will result in a compiler error. You also just mash all the variables together, without quotes or commas between them. You probably want something more like:
sql += String.Format("INSERT into Student VALUES('{0}', '{1}', '{2}');", StudentId, Name, Address);
Use parameterized queries. Always. Who cares what your teacher says. If you don't, at the very least, check the strings for apostrophes first, as these will screw up your SQL statement by prematurely ending the string.
Your loop doesn't seem to make much sense. What is counter1? What value does it have? Even if it's set to a positive value, all you're doing is building the same SQL string over and over again since the values within the loop don't change. It's not clear what you're trying to do here.
You're calling varname1.Close(); but you've commented out the declaration of varname1, which will result in a compiler error.
Hope this helps!
Is this what you are after. You may have to adapt some of it. Sorry if it doesent fully work dont have a debugger at the moment.
class Data {
public int StudentId {get;set;}
public string Name {get;set;}
public string Address {get;set;}
}
protected void btnDisplay_Click(object sender, EventArgs e)
{
var datas = new List<Data>();
try
{
StringBuilder sql = new StringBuilder();
foreach(data in datas)
{
sql.Append(String.Format("INSERT into Student VALUES({0},'{1}','{2}') ",data.UserId,data.Name,data.Address));
}
var sqlConnection = new SqlConnection(#"Data Source=LOCALHOST;Initial Catalog=Lab1;Trusted_Connection=True;");
sqlConnection.Open();
var command = new SqlCommand(sql.ToString(),sqlConnection);
command..ExecuteNonQuery();
sqlConnection.Close();
}
catch(SqlException ex){
MessageBox.Show("Database failed" + ex.Message);
}
}