i'm trying to delete a row giving a value of a column, but it only deletes when i give the full value (i.e name column = sam jack) then to delete it i have to input sam jack.
so i'm trying to use the % operator but don't know how to put it in the query.
here is my code :
command.CommandText = "DELETE FROM dbo.workers WHERE Name like #name" + "%";
You are doing it wrong.
Use parameterized queries also.
command.CommandText = "DELETE FROM dbo.workers WHERE Name like #name";
command.Parameters.AddWithValue("#name","%" + searchString + "%");
Or if you want to delete only starts with your string, don't use first % like;
command.Parameters.AddWithValue("#name", searchString + "%");
You can either concatenate % and the parameter value in the host language, or you can do it in SQL:
command.CommandText = "DELETE FROM dbo.workers WHERE Name like #name+'%'";
In SQL Server 2012 you can use CONCAT to be more explicit:
command.CommandText = "DELETE FROM dbo.workers WHERE Name like CONCAT(#name, '%')";
Related
I was wondering why this SQL Query doesn't return anything:
mySqlCommand.CommandText = "SELECT * FROM `users` WHERE Username LIKE %#Username% ORDER BY Id DESC";
mySqlCommand.Parameters.AddWithValue("#Username", this.search.Text);
IT's not a reader problem or anything like this, if i remove "WHERE Username LIKE %#Username% ", it works fine.
I call this whole MySQL-Query in a KeyPress-Event of a Textbox.
this.search is the Textbox. I want to search for rows where the Username Column contains the Characters i entered in the Textbox.
Try to use
//For LIKE query
SqlParameter parameter = new SqlParameter("#query", SqlDbType.NVarChar);
parameter.Value = string.Format("%{0}%", this.search.Text);
IList<Users> results = ctx.Database.SqlQuery<Users>("SELECT * FROM Users WHERE Username LIKE #query", parameter).ToList();
I solved it using this:
mySqlCommand.CommandText = "SELECT * FROM `users` WHERE Username LIKE #Username ORDER BY Id DESC";
mySqlCommand.Parameters.AddWithValue("#Username", "%" + this.search.Text + "%");
I would strongly recommend using a stored procedure, will help against SQL Injection attacks, and you want to disallow your app to use insert, update and delete scripts and only allow it to use execute statements for stored procedures.
But you want to change this line from
mySqlCommand.CommandText = "SELECT * FROMusersWHERE Username LIKE %#Username% ORDER BY Id DESC";
to
mySqlCommand.CommandText = "SELECT * FROMusersWHERE Username LIKE '%#Username%' ORDER BY Id DESC";
I am trying to pull data from my table based on the button a user clicks, so if they click the 1940's button it will pull all products from that decade but I cant get the query to work. It has to do with the #decade parameter because that is where I am getting the user input from but it doesnt like it when I am trying to choose a column using that parameter
ImageButton decadeBtn = (ImageButton)sender;
var decade = decadeBtn.CommandArgument;
yearHead.InnerText = decade.ToString();
string cmd="";
DataSet ds;
if (typeOfArchive == "On Hand")
{
cmd = #"Select * From ARCHIVE_DECADE_TBL WHERE DECADE_#decade=#decade AND PRODUCT_LINE=#Line AND LOCATION is not null;";
}
else if(typeOfArchive == "All Other"){
cmd = #"Select * From ARCHIVE_DECADE_TBL WHERE DECADE_#decade=#decade AND PRODUCT_LINE=#Line AND LOCATION is null";
}
using (OleDbConnection dbConn = new OleDbConnection(connectionString))
using (OleDbDataAdapter dbCmdDecade = new OleDbDataAdapter(cmd, dbConn))
{
dbConn.Open();
dbCmdDecade.SelectCommand.Parameters.Add("#decade", OleDbType.Integer).Value = decade;
dbCmdDecade.SelectCommand.Parameters.Add("#line", OleDbType.VarChar).Value = productLine;
ds = new DataSet();
dbCmdDecade.Fill(ds, "products");
}
No you can't use a parameter in that way. As a rule, you cannot use a parameter to define a column name or a table name (or concatenating it to form a column name). A parameter could only be used to define a value used in the query. (or with a stored procedure to create an SQL Text inside the sp to be executed but that is another more complex story),
However, assuming that you are not allowing your users to type directly the decade value (Sql Injection vulnerability), then it is pretty simple to create a string with the column name desidered and use it in your query.
Add a method that just concatenate together you decade string with your prefix for the DECADE column
private string GetDecadeColumn(string decade)
{
return "DECADE_" + decade;
}
and in you query
if (typeOfArchive == "On Hand")
{
cmd = #"Select * From ARCHIVE_DECADE_TBL WHERE " +
GetDecadeColumn(decade) +
" AND PRODUCT_LINE=#Line AND LOCATION is not null;";
}
else if(typeOfArchive == "All Other"){
cmd = #"Select * From ARCHIVE_DECADE_TBL WHERE " +
GetDecadeColumn(decade) +
" AND PRODUCT_LINE=#Line AND LOCATION is null";
}
So ARCHIVE_DECADE_TBL has columns that are named something like DECADE_1990 with a value of 1990, DECADE_2000 with a value of 2000, etc?
It really should be designed to just be called "DECADE" with the value being 1990/2000/etc, but if that's not possible, you'll have to build your query dynamically. I don't believe those parameters will work to set the column name. They can set a value to check for, but not the column names.
You'll have to build the query out manually in c#, so something like:
cmd = #"Select * From ARCHIVE_DECADE_TBL WHERE DECADE_" + decade + #" = #decade AND PRODUCT_LINE=#Line AND LOCATION is not null;";
Now, if I misunderstood and your column is actually named DECADE_#decade, then I think you'll just need to change your variable so it's not #decade, so something like #mydecade. The conflict there will confuse it.
Sooooo like...
cmd = #"Select * From ARCHIVE_DECADE_TBL WHERE DECADE_#decade=#mydecade AND PRODUCT_LINE=#Line AND LOCATION is not null;";
And then down below:
dbCmdDecade.SelectCommand.Parameters.Add("#mydecade", OleDbType.Integer).Value = decade;
That probably shouldn't have an # in the column name though. :)
I have a query to insert a row into a table, which has a field called ID, which is populated using an AUTO_INCREMENT on the column. I need to get this value for the next bit of functionality, but when I run the following, it always returns 0 even though the actual value is not 0:
MySqlCommand comm = connect.CreateCommand();
comm.CommandText = insertInvoice;
comm.CommandText += "\'" + invoiceDate.ToString("yyyy:MM:dd hh:mm:ss") + "\', " + bookFee + ", " + adminFee + ", " + totalFee + ", " + customerID + ")";
int id = Convert.ToInt32(comm.ExecuteScalar());
According to my understanding, this should return the ID column, but it just returns 0 every time. Any ideas?
EDIT:
When I run:
"INSERT INTO INVOICE (INVOICE_DATE, BOOK_FEE, ADMIN_FEE, TOTAL_FEE, CUSTOMER_ID) VALUES ('2009:01:01 10:21:12', 50, 7, 57, 2134);last_insert_id();"
I get:
{"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 'last_insert_id()' at line 1"}
MySqlCommand comm = connect.CreateCommand();
comm.CommandText = insertStatement; // Set the insert statement
comm.ExecuteNonQuery(); // Execute the command
long id = comm.LastInsertedId; // Get the ID of the inserted item
[Edit: added "select" before references to last_insert_id()]
What about running "select last_insert_id();" after your insert?
MySqlCommand comm = connect.CreateCommand();
comm.CommandText = insertInvoice;
comm.CommandText += "\'" + invoiceDate.ToString("yyyy:MM:dd hh:mm:ss") + "\', "
+ bookFee + ", " + adminFee + ", " + totalFee + ", " + customerID + ");";
+ "select last_insert_id();"
int id = Convert.ToInt32(comm.ExecuteScalar());
Edit: As duffymo mentioned, you really would be well served using parameterized queries like this.
Edit: Until you switch over to a parameterized version, you might find peace with string.Format:
comm.CommandText = string.Format("{0} '{1}', {2}, {3}, {4}, {5}); select last_insert_id();",
insertInvoice, invoiceDate.ToString(...), bookFee, adminFee, totalFee, customerID);
Use LastInsertedId.
View my suggestion with example here: http://livshitz.wordpress.com/2011/10/28/returning-last-inserted-id-in-c-using-mysql-db-provider/
It bothers me to see anybody taking a Date and storing it in a database as a String. Why not have the column type reflect reality?
I'm also surprised to see a SQL query being built up using string concatenation. I'm a Java developer, and I don't know C# at all, but I'd wonder if there wasn't a binding mechanism along the lines of java.sql.PreparedStatement somewhere in the library? It's recommended for guarding against SQL injection attacks. Another benefit is possible performance benefits, because the SQL can be parsed, verified, cached once, and reused.
Actually, the ExecuteScalar method returns the first column of the first row of the DataSet being returned. In your case, you're only doing an Insert, you're not actually querying any data. You need to query the scope_identity() after you're insert (that's the syntax for SQL Server) and then you'll have your answer. See here:
Linkage
EDIT: As Michael Haren pointed out, you mentioned in your tag you're using MySql, use last_insert_id(); instead of scope_identity();
I am using VS2005 C# ASP.NET and SQL Server 2005.
I have a search function on my asp page and I feel that my SELECT query is vulnerable to SQL injection.
This is my current SELECT statement:
string LoggedInUser = (User.Identity.Name);
SqlDataSource1.SelectCommand = "SELECT * FROM [TABLE1] where [" + DropDownList1.Text + "] like '%" + searchTB.Text + "%' AND [empUser] LIKE '%"+LoggedInUser+"%'";
SqlDataSource1.DataBind();
*where searchTB is my search text box; DropDownList1 is my search category; and LoggedInUser is the username of the logged in user.
I have implemented parameter instead of concatenation in one of my INSERT statement:
string sql = string.Format("INSERT INTO [TABLE2] (Username) VALUES (#Username)");
SqlCommand cmd = new SqlCommand(sql, conn);
cmd.Parameters.AddWithValue("Username", usernameTB.Text);
conn.Open();
cmd.ExecuteNonQuery();
conn.Close();
I would like to change my SELECT statement like my INSERT statement, using parameter instead. May I know how should I change it?
Thank you
You can add parameters to your selectcommand using
SqlDataSource s = new SqlDataSource();
s.SelectParameters.Add("paramName", "paramValue");
There are other parameter collections for delete, update and insert too.
s.DeleteParameters
s.UpdateParameters
s.InsertParameters
More Information:
MSDN: SqlDataSource.SelectParameters Property
Programmatically Using SqlDataSource
hope this helps
See Using Parameters with the SqlDataSource Control
And SqlDataSource.SelectParameters Property
You can specify SelectParameters Property for SqlDataSource to use parameterized SQL query
Write a method that gets the data sourse and use sql parameters for the query. Here is a good example how to add parameters in a command object
SqlCommand command = new SqlCommand(commandText, connection);
command.Parameters.Add("#ID", SqlDbType.Int);
command.Parameters["#ID"].Value = customerID;
I would use a method for the query so that I separate the Database Access from the UI functionality. Also, this allows to reuse the query.
It's not a straightforward task to dynamically specify a fieldname in query, so I'd suggest just doing switch/case validation for field name, like this:
switch (DropDownList1.Text)
{
case "ValidField1":
case "ValidField2":
...
break;
default:
throw new ArgumentException(...); // or prevent query execution with some other statement
}
SqlDataSource1.SelectCommand = "SELECT * FROM [TABLE1] where [" + DropDownList1.Text + "] like #value AND [empUser] LIKE #user";
SqlDataSource1.SelectParameters.Add("value", "%" + searchTB.Text + "%");
SqlDataSource1.SelectParameters.Add("user", "%"+LoggedInUser+"%");
SqlDataSource1.DataBind();
You can simply use a filter expression for the SQL datasource SQL Datasource filter expression
You can write your own select function method with object datasource/datatable
I have a query to insert a row into a table, which has a field called ID, which is populated using an AUTO_INCREMENT on the column. I need to get this value for the next bit of functionality, but when I run the following, it always returns 0 even though the actual value is not 0:
MySqlCommand comm = connect.CreateCommand();
comm.CommandText = insertInvoice;
comm.CommandText += "\'" + invoiceDate.ToString("yyyy:MM:dd hh:mm:ss") + "\', " + bookFee + ", " + adminFee + ", " + totalFee + ", " + customerID + ")";
int id = Convert.ToInt32(comm.ExecuteScalar());
According to my understanding, this should return the ID column, but it just returns 0 every time. Any ideas?
EDIT:
When I run:
"INSERT INTO INVOICE (INVOICE_DATE, BOOK_FEE, ADMIN_FEE, TOTAL_FEE, CUSTOMER_ID) VALUES ('2009:01:01 10:21:12', 50, 7, 57, 2134);last_insert_id();"
I get:
{"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 'last_insert_id()' at line 1"}
MySqlCommand comm = connect.CreateCommand();
comm.CommandText = insertStatement; // Set the insert statement
comm.ExecuteNonQuery(); // Execute the command
long id = comm.LastInsertedId; // Get the ID of the inserted item
[Edit: added "select" before references to last_insert_id()]
What about running "select last_insert_id();" after your insert?
MySqlCommand comm = connect.CreateCommand();
comm.CommandText = insertInvoice;
comm.CommandText += "\'" + invoiceDate.ToString("yyyy:MM:dd hh:mm:ss") + "\', "
+ bookFee + ", " + adminFee + ", " + totalFee + ", " + customerID + ");";
+ "select last_insert_id();"
int id = Convert.ToInt32(comm.ExecuteScalar());
Edit: As duffymo mentioned, you really would be well served using parameterized queries like this.
Edit: Until you switch over to a parameterized version, you might find peace with string.Format:
comm.CommandText = string.Format("{0} '{1}', {2}, {3}, {4}, {5}); select last_insert_id();",
insertInvoice, invoiceDate.ToString(...), bookFee, adminFee, totalFee, customerID);
Use LastInsertedId.
View my suggestion with example here: http://livshitz.wordpress.com/2011/10/28/returning-last-inserted-id-in-c-using-mysql-db-provider/
It bothers me to see anybody taking a Date and storing it in a database as a String. Why not have the column type reflect reality?
I'm also surprised to see a SQL query being built up using string concatenation. I'm a Java developer, and I don't know C# at all, but I'd wonder if there wasn't a binding mechanism along the lines of java.sql.PreparedStatement somewhere in the library? It's recommended for guarding against SQL injection attacks. Another benefit is possible performance benefits, because the SQL can be parsed, verified, cached once, and reused.
Actually, the ExecuteScalar method returns the first column of the first row of the DataSet being returned. In your case, you're only doing an Insert, you're not actually querying any data. You need to query the scope_identity() after you're insert (that's the syntax for SQL Server) and then you'll have your answer. See here:
Linkage
EDIT: As Michael Haren pointed out, you mentioned in your tag you're using MySql, use last_insert_id(); instead of scope_identity();