Selecting specific records in a SQL Server database from C #

Question

I am currently trying to grab some rows from a SQL Server database using C #, which have the following criteria:

• From the RamResults
• in the table Results
• where the Date column is the current date

I have the following:

 // Open the same connection with the same connection string. using (SqlCeConnection con = new SqlCeConnection(DatabaseControl.conString)) { con.Open(); // Read specific values in the table. using (SqlCeCommand com = new SqlCeCommand("SELECT Result FROM RamResults WHERE Date == @Form1.date", con)) { SqlCeDataReader reader = com.ExecuteReader(); while (reader.Read()) { int resultsoutput = reader.GetInt32(0); MessageBox.Show(resultsoutput.ToString()); } } } 

Using SELECT Result FROM RamResults WHERE Date == Form1.date causes an error:

An error occurred while parsing the request. [Token line number = 1, token line offset = 43, token with error = =]

Although I take out the WHERE statement, for example.

 SELECT Result FROM RamResults 

it works great

Answer 1

Description

2 things

• Use = instead of == because it is the correct equality operator in T-SQL . Your request should look like this

  SELECT Result FROM RamResults WHERE Date = @Date

• You forgot to pass the parameter.

Example

 // Open the same connection with the same connection string. using (SqlCeConnection con = new SqlCeConnection(DatabaseControl.conString)) { con.Open(); // Read specific values in the table. using (SqlCeCommand com = new SqlCeCommand("SELECT Result FROM RamResults WHERE Date = @Date", con)) { com.Parameters.AddWithValue("@Date", Form1.date); SqlCeDataReader reader = com.ExecuteReader(); while (reader.Read()) { int resultsoutput = reader.GetInt32(0); MessageBox.Show(resultsoutput.ToString()); } } } 

Answer 2

Try parameterizing your query and replace == with = in the WHERE :

 // ... using (SqlCeCommand com = new SqlCeCommand("SELECT Result FROM RamResults WHERE Date = @date", con)) { com.Parameters.Add(new SqlParameter("date", Form1.date)); // ... } // ... 

Answer 3

Try the following:

 using (SqlCeCommand com = new SqlCeCommand("SELECT Result FROM RamResults WHERE Date = @date", con)) { com.Parameters.AddWithValue("date",Form1.date); SqlCeDataReader reader = com.ExecuteReader(); while (reader.Read()) 

Always use SQL parameters instead of string concatenation.

Answer 4

Not == , use = for the equation in SQL:

 WHERE Date = @Form1.date 

Answer 5

The operator "==" is not valid syntax for SQL. Use the single equal sign "=" in the where clause.

Answer 6

Try

 var query = "SELECT Result FROM RamResults WHERE Date = " + Form1.date; using (SqlCeCommand com = new SqlCeCommand(query, con)) 

I would suggest using parameters, as in the example on MSDN

Answer 7

Replace SQL Query with the following text:

 SELECT Result FROM RamResults WHERE Date like DATEADD(day, DATEDIFF(day, 0, getdate()), 0) 

Hope this works.

Answer 8

This is quite confusing, and many people make similar mistakes. While C # uses == for equality operations (Ok We also have Equal ()), SQL uses just = for it.

In addition, you also forgot to pass the parameter here

Answer 9

I found two things in your code that are creating a problem

1) assign values ​​to parameter 2) == instead of = (just to work correctly with SQL)

so the code should look like this:

 using (SqlCeConnection con = new SqlCeConnection(DatabaseControl.conString)) { con.Open(); using (SqlCeCommand com = new SqlCeCommand("SELECT Result FROM RamResults WHERE Date = @Date", con)) { com.Parameters.AddWithValue("@Date", Form1.date); SqlCeDataReader reader = com.ExecuteReader(); while (reader.Read()) { int resultsoutput = reader.GetInt32(0); MessageBox.Show(resultsoutput.ToString()); } } }