Develop Reference

Syntax Error while Inserting variables into a table Visual Studios 2015 C#

I'm confused at the moment about what it means exactly about my current syntax error issue while trying to save/insert answers into a table in my database. It worked fine when I attempted this with hardcoded variables but now is not the case.
Part of the error message:
Additional information: Incorrect syntax near ')'
Not sure what I'm doing wrong. Below is the code I'm using and the location where the error is pointing to. Thank you for any possible assistance and clarification.
protected void btnSaveAnswers_Click(object sender, EventArgs e)
{
Int32 int32StudentID = Convert.ToInt32(Session["StudentID"]);
Int32 int32QuestionID = Convert.ToInt32(Session["QuestionID"]);
String strAnswer = "";
// Save the student's answer to the Answer table.
// Develop the SQL call.
String strSQL = "";
strSQL = "INSERT ";
strSQL += "INTO Answer ";
strSQL += " (StudentID, QuestionID, Answer) ";
strSQL += "VALUES ";
strSQL += " ( " + int32StudentID + ", " + int32QuestionID + ", " + strAnswer + ")";
// Define the network connection to the SQL Server database.
SqlConnection objSqlConnection = new SqlConnection(WebConfigurationManager.ConnectionStrings["OPT"].ConnectionString);
// Create the SQL command object.
SqlCommand objSqlCommand = new SqlCommand();
objSqlCommand.Connection = objSqlConnection;
objSqlCommand.CommandType = CommandType.Text;
objSqlCommand.CommandText = strSQL;
// Open the connection.
objSqlConnection.Open();
// Execute the Insert statement.
objSqlCommand.ExecuteNonQuery();
// Close the connection.
objSqlConnection.Close();
this.Master.MessageForeColor = System.Drawing.Color.White;
this.Master.Message = "You have saved your answer for this question, click next to continue.";
}

First you should not be building SQL statements like this, it is prone to many problems, but your issue is with your string, you do not have single quotes around it:
strSQL += " ( " + int32StudentID + ", " + int32QuestionID + ", '" + strAnswer + "')";
Need to add the single quotes around strAnswer like I have above
Use parameters outlined here:
https://msdn.microsoft.com/library/bb738521(v=vs.100).aspx

I agree with the comment about concatenation of strings. If you have to write a SQL query in code, you should user string interpolation.
If I had to do it, I would write it like this:
String strSQL = $"INSERT INTO Answer (StudentID, QuestionID, Answer) VALUES ( {int32StudentID}, {int32QuestionID}, '{strAnswer}')";
That said, that is not why you have a syntax error. You are missing single quotes around your string variable. Try this:
strSQL += " ( " + int32StudentID + ", " + int32QuestionID + ", '" + strAnswer + "')";

The error is at this line
strSQL += " ( " + int32StudentID + ", " + int32QuestionID + ", " + strAnswer + ")";
As per your SQL Query and database the field Answer is a field of type varchar or nvarchar. This type of field always takes value of string type. Which is done by you already. But SQL Server database accept these values inside the single quotation ''. Thus your solve is
strSQL += " ( " + int32StudentID + ", " + int32QuestionID + ", '" + strAnswer + "')";
as I've added a single quotation in front of strAnswer and at the last of strAnswer
Thank you.

MySqlDataAdapter Update table that uses Inner Join

I'm tring to add the Insert, Update and Delete commands to a MySqlDataAdapter which has the data added to it with the command:
//iec211.4521studenti
string lv_sObsTable = "`" + mv_sDatabase + "`.`" + mv_sGroup + "observatii`";
string lv_sStudTable = "`" + mv_sDatabase + "`.`" + mv_sGroup + "studenti'";
string lv_sObservatiiCommand = "SELECT o.idObservatie, o.idStudent, s.nume, o.observatie, o.lastUpdate FROM " + lv_sObsTable + " o INNER JOIN " + lv_sStudTable + " s USING (idStudent) ORDER BY s.nume ASC";
mv_dtAdapterObservatii = new MySqlDataAdapter(lv_sObservatiiCommand, mv_sqlConnection);
mv_dtAdapterObservatii.Fill(mv_dsTables, lv_sCurrentTable);
I've serched for an answer and I've found two possible solutions for UPDATE, but both of them give me an error:
string lv_sObsTB = "`" + mv_sDatabase + "`.`" + mv_sGroup + "observatii`";
string lv_sStudTB = "`" + mv_sDatabase + "`.`" + mv_sGroup + "studenti`";
//VERSION 1
string lv_sCommand = "UPDATE o SET s.idStudent=#idStudent, o.observatie=#observatie FROM " + lv_sObsTB + " AS o INNER JOIN " + lv_sStudTB + " s ON o.idStudent=s.idStudent ";
MySqlCommand lv_sqlCommand = new MySqlCommand(lv_sCommand);
lv_sqlCommand.Parameters.Add("#idStudent", MySqlDbType.Int16, 10, "idStudent");
lv_sqlCommand.Parameters.Add("#observatie", MySqlDbType.VarChar, 255, "observatie");
mv_dtAdapterObservatii.UpdateCommand = lv_sqlCommand;
//VERSION 2
string lv_sCommand = "UPDATE " + lv_sObsTB + " SET " + "idStudent=#" + lv_sStudTB + ".idStudent, observatie=#observatie WHERE idObservatie=#idObservatie AND " + lv_sObsTB + ".idStudent IN (SELECT " + lv_sStudTB + ".idStudent FROM " + lv_sStudTB + ")";
MySqlCommand lv_sqlCommand = new MySqlCommand(lv_sCommand);
lv_sqlCommand.Parameters.Add("#" + lv_sStudTB + ".idStudent", MySqlDbType.Int16, 10, "idStudent");
lv_sqlCommand.Parameters.Add("#observatie", MySqlDbType.VarChar, 255, "observatie");
lv_sqlCommand.Parameters.Add("#idObservatie", MySqlDbType.Int16, 10, "idObservatie");
mv_dtAdapterObservatii.UpdateCommand = lv_sqlCommand;
The error message for the first version is : "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 'FROM iec211.4521observatii ASS o INNER JOIN iec211.4521studenti s ON o.id' at line 1"
The error message for the second version is: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 '.4521studenti'.idStudenti, observatie='test' WHERE idObservatie=1 ANDiec211.' at line 1"
I don't know how to use the MySQL commands in combination with MySqlCommand and MySqlDataAdapter.
Until now I've used the following command to obtain data for my table:
string lv_sObservatiiCommand = "SELECT * FROM `" + mv_sDatabase + "`.`" + mv_sGroup + "observatii` ORDER BY idStudent ASC";
mv_dtAdapterObservatii = new MySqlDataAdapter(lv_sObservatiiCommand, mv_sqlConnection);
mv_dtAdapterObservatii.Fill(mv_dsTables, lv_sCurrentTable);
In combination with MySqlCommandBuilder to get the update command and the parameters that needed to be setted:
lv_sqlCommandBuilder = new MySqlCommandBuilder(mv_dtAdapterObservatii);
mv_dtAdapterObservatii.UpdateCommand = lv_sqlCommandBuilder.GetUpdateCommand();
Can someone please explain to me how to correctly add the insert, update and delete commands to a MySqlDataAdapter that contains an INNER JOIN between 2 tables ?
I know that each table must be in a different data adapter, and they are. The "4521studenti" table is inside "mv_dtAdapterStudenti", which is not included in the code above.
Thank you for the help and I hope this won't be considered as a bad post. :)

Okey. I think I've figured it out.
This is the SELECT command for 4521observatii:
string lv_sStudent = "`" + mv_sDatabase + "`.`" + mv_sGroup + "studenti`";
string lv_sObservatii = "`" + mv_sDatabase + "`.`" + mv_sGroup + "observatii`";
string lv_sObservatiiCommand = "SELECT o.idObservatie, o.idStudent, s.nume, o.observatie, o.lastUpdate FROM " + lv_sObservatii + " o INNER JOIN " + lv_sStudent + " s USING (idStudent) ORDER BY s.nume ASC";
// Read data from the server for the current table and add it to the DataSet
mv_dtAdapterObservatii = new MySqlDataAdapter(lv_sObservatiiCommand, mv_sqlConnection);
mv_dtAdapterObservatii.Fill(mv_dsTables, lv_sCurrentTable);
And this is the code for the UPDATE command, inside a different method:
// `iec211`.`4521observatii`
string lv_sObsTB = "`" + mv_sDatabase + "`.`" + mv_sGroup + "observatii`";
// `iec211`.`4521studenti`
string lv_sStudTB = "`" + mv_sDatabase + "`.`" + mv_sGroup + "studenti`";
string lv_sSelectStudenti = "(SELECT idStudent FROM " + lv_sStudTB + " WHERE idStudent=#idStudent)";
string lv_sCommand = "UPDATE " + lv_sObsTB + " SET idStudent="+ lv_sSelectStudenti + ", observatie=#observatie WHERE idObservatie=#idObservatie";
MySqlCommand lv_sqlCommand = new MySqlCommand(lv_sCommand);
lv_sqlCommand.Parameters.Add("#idStudent", MySqlDbType.Int16, 10, "idStudent");
lv_sqlCommand.Parameters.Add("#observatie", MySqlDbType.VarChar, 255, "observatie");
lv_sqlCommand.Parameters.Add("#idObservatie", MySqlDbType.Int16, 10, "idObservatie");
mv_dtAdapterObservatii.UpdateCommand = lv_sqlCommand;
mv_dtAdapterObservatii.UpdateCommand.Connection = mv_sqlConnection;
The idea is that when I use INNER JOIN I bring data from two different tables and put them together. When I used the UPDATE command, the program didn't know which table he was using and gived those errors.
So I thought what if I update the values of 4521observatii and for the column that is used as FOREIGN KEY I assign the value from 4521studenti.
I know it's like "Tell me your name so I can tell you your name.", but it worked for me.
I hope this will help others and you have a better and cleaner solution, pleas tell me :)

Update/Insert into table

I have to update table on SQL Server but first i have to check for existing data in table so if data is there update it, if not make a new insert:
cmd_sql.CommandText = " SELECT BrDok as id_dok " +
" FROM ordersstavke " +
" WHERE SifParFil = '" + rw_mat["sifskl_kor"] + "'" +
" AND DokumentTip = '" + rw_mat["vrst_dok"] + "'";
MySqlDataAdapter sql_adapter = new MySqlDataAdapter(cmd_sql);
DataSet dt_dok = new DataSet("DOK_MAT_EXCHANGE");
sql_adapter.Fill(dt_dok);
if (dt_dok.Tables["DOK_MAT_EXCHANGE"].Rows.Count == 0)
{
myQuery = " INSERT INTO ordersstavke (BrDok, DocumentTip, SifParFil) " +
" VALUES ('" + rw_mat["brdok"] + "', '" +
rw_mat["vrst_dok"] + "', '" +
rw_mat["sifskl_kor"] + "')";
}
else
{
UPDATE DATA
}
But I have an error in the code, the error is here if (dt_dok.Tables["DOK_MAT_EXCHANGE"].Rows.Count == 0)
Object reference not set to an instance of an object.
The problem is in this if statement...

DOK_MAT_EXCHANGE is the name of the DataSet, not of the first table.
You should test with
if (dt_dok.Tables[0].Rows.Count == 0)
Also, I think is better to use a syntax like this to discover how many records are presents
cmd_sql.CommandText = "SELECT COUNT(BrDok) as id_dok " +
" FROM ordersstavke " +
" WHERE SifParFil = ?p1 " +
" AND DokumentTip = ?p2";
cmd_sql.Parameters.AddWithValue("?p1", rw_mat["sifskl_kor"] );
cmd_sql.Parameters.AddWithValue("?p2", rw_mat["vrst_dok"] );
int rowCount = (Int32)cmd_sql.ExecuteScalar();

change
DataSet dt_dok = new DataSet("DOK_MAT_EXCHANGE");
to
DataSet dt_dok = new DataSet("ordersstavke ");
and
if (dt_dok.Tables["DOK_MAT_EXCHANGE"].Rows.Count == 0)
to
if (dt_dok.Tables["ordersstavke "].Rows.Count == 0)

Accessing the first table via the dataset name is incorrect, that's for setting the XML.
Instead use
dt_dok.Tables[0].Rows.Count;
That being said, you're better off writing this as a single SQL statement instead of a separate select && insert. This way you're not going to the DB multiple times.
var sql = #"if exists(select * from ordersstavke where SifParFil = ? and DokumentTip = ?)
then
-- do insert statement
else
-- do update
end if";
This might also be better done with a stored proc, so you don't have as much SQL code in C#. It's easier to manage multiple operations that way.
And for crying out loud, use SqlParameters, not string concatenation! That's just asking for trouble!

Ok, thanks guys, I wrote it like this
if (ds_dok.Tables[0].Rows.Count <= 0)
{
myQuery = " INSERT INTO ordersstavke (BrDok, " +
" SifParFil) " +
" VALUES ('" + rw_mat["brdok"] + "', '" +
rw_mat["sifskl_kor"] + "')";
}
else if (ds_dok.Tables[0].Rows.Count >= 1)
{
myQuery = "UPDATE ordersstavke " +
"SET BrDok = '" + rw_mat["brdok"] + "', " +
"SifParFil = '" + rw_mat["sifskl_kor"] + "', " +
"WHERE BrDok = " + ds_dok.Tables["ordersstavke"].Rows[0]["BrDok"].ToString() + "'";
}
But there is a small problem in the section update: s_dok.Tables["ordersstavke"].Rows[0]["BrDok"].ToString(), here it give me that loving error : Object reference not set to an instance of an object.
Maybe the update on MySQL goes on different way, I'm referencing on example on sql server and there update goes differently

how to execute SQL with if condition in c#

how to execute SQL with if condition in c#?
This is my query and went i execute this query i get an error saying "Invalid SQL statement; expected 'DELETE', 'INSERT', 'PROCEDURE', 'SELECT', or 'UPDATE'."
I m using MS ACCESS as back end
mycon.ConnectionString = ConnString;
mycon.Open();
string mySelectQuery = "IF (EXISTS (SELECT * FROM Employee AS t1 WHERE t1.ssn ='"+textBox4.Text+"' "+
"))begin UPDATE Employee SET "+
"fname ='"+textBox1.Text+"' ,"+
"minit ='"+textBox2.Text+"' ," +
"lname ='" + textBox3.Text+"', " +
"ssn ='" +textBox4.Text+"', " +
"bdate ='" +textBox5.Text+"', " +
"address ='" +textBox6.Text+"', " +
"sex ='" +textBox7.Text+ "', " +
"salary ='" +textBox8.Text+"', " +
"superssn ='" +textBox9.Text+"', " +
"dno ='" +comboBox2.Text+"'" +
" WHERE ssn = '"+textBox4.Text+"' "+
"end "+
"else "+
" begin "+
" INSERT INTO employee values ('"+textBox1.Text+"','"+textBox2.Text+"','"+textBox3.Text+"','"+textBox4.Text+"','"+textBox5.Text+"','"+textBox6.Text+"','"+textBox7.Text+"','"+textBox8.Text+"','"+textBox9.Text+"','"+comboBox2.Text+"')"+
" end";
OleDbCommand myCommand = new OleDbCommand(mySelectQuery, mycon);
int Success= myCommand.ExecuteNonQuery();

MS Access doesn't support the IF statement. Nor else or begin. You'll have to do this in your C# code, such as performing your "SELECT * FROM Employee AS t1 WHERE t1.ssn ='"+textBox4.Text + "'"; query first and then performing the next one if there are results.
Also, you should either use a parameterized queries or escape the values of you text boxes.

Seems like what you want to happen is UPDATE a record if it Exists in database, else INSERT a record.
You can't do this in one query, so prepare a query for a look-up in database if the record exists, then use the output (isExists or not) to UPDATE or INSERT

How can you use parameterized statements with DB2 Text Search?

I've tried this:
select * from ourschema.mytable
where contains(mysearchablefield, #searchTerms) = 1;
Where #searchTerms was set to "search terms"
Unfortunately, it only produced an error:
ERROR [42610] [IBM][DB2/NT] SQL0418N A statement contains a use of a parameter marker that is not valid. SQLSTATE=42610
Is there a way to use parameterized queries for text search with DB2? If not, is there a document which describes the syntax in detail for manual (ugh) escaping of the search terms (quotes, etc)?

Instead of #field you need to use "?". Everything is basically the same.
Okay, here is a live code sample.
sqlStmt = "SELECT COMPLAINT_NUMBER, VIOLATION_NUMBER, COMMON_ADDRESS_KEY, " +
"DEPT_CODE, DEPT_CODE_DESC, DIVISION_CODE, DIVISION_CODE_DESC, " +
"EMPLOYEE_NAME, COMPLAINT_CODE, COMPLAINT_CODE_DESC, COMPLAINT_DATE, " +
"COMMON_ADDRESS_OWNER, RESOLUTION_CODE, 1 AS SORTORDER " +
"FROM QMFILES/NVMASTP " +
"WHERE VCLOSEDATE = 0 AND " +
"DEPT_CODE LIKE #DEPT_CODE1 AND " +
"DIVISION_CODE LIKE #DIVISION_CODE1 AND " +
"COMPLAINT_DATE BETWEEN #FROM_COMPLAINT_DATE1 AND #TO_COMPLAINT_DATE1 " +
statusQry +
"UNION " +
"SELECT COMPLAINT_NUMBER, VIOLATION_NUMBER, COMMON_ADDRESS_KEY, " +
"DEPT_CODE, DEPT_CODE_DESC, DIVISION_CODE, DIVISION_CODE_DESC, " +
"EMPLOYEE_NAME, COMPLAINT_CODE, COMPLAINT_CODE_DESC, COMPLAINT_DATE, " +
"COMMON_ADDRESS_OWNER, RESOLUTION_CODE, 2 AS SORTORDER " +
"FROM QMFILES/NVMASTP " +
"WHERE VCLOSEDATE <> 0 AND " +
"DEPT_CODE LIKE #DEPT_CODE2 AND " +
"DIVISION_CODE LIKE #DIVISION_CODE2 AND " +
"COMPLAINT_DATE BETWEEN #FROM_COMPLAINT_DATE2 AND #TO_COMPLAINT_DATE2 " +
statusQry +
"ORDER BY DEPT_CODE, DIVISION_CODE, COMPLAINT_CODE, SORTORDER";
iDB2Command cmd = new iDB2Command(sqlStmt, conn);
conn.Open();
cmd.DeriveParameters();
conn.Close();
cmd.Parameters["#DEPT_CODE1"].Value = dept;
cmd.Parameters["#DIVISION_CODE1"].Value = serviceArea;
cmd.Parameters["#DEPT_CODE2"].Value = dept;
cmd.Parameters["#DIVISION_CODE2"].Value = serviceArea;
cmd.Parameters["#FROM_COMPLAINT_DATE1"].Value = Convert.ToDecimal(fromDateString);
cmd.Parameters["#TO_COMPLAINT_DATE1"].Value = Convert.ToDecimal(toDateString);
cmd.Parameters["#FROM_COMPLAINT_DATE2"].Value = Convert.ToDecimal(fromDateString);
cmd.Parameters["#TO_COMPLAINT_DATE2"].Value = Convert.ToDecimal(toDateString);
I hope this helps you out more.