Sqlite "Update" C# Syntax Error

Others have suggested alternative ways of constructing the SQL, but you shouldn't be including the values in the SQL at all. You should be using a parameterized query, which avoids SQL injection attacks amongst other things.

It's not immediately clear to me which driver you're using, but assuming it's the Devart.com one, the documentation for SQLiteCommand.Parameters gives a good example of how to do this. In your case, the code would become something like:

string dataSource = "Database.s3db";using (SQLiteConnection connection = new SQLiteConnection()){    connection.ConnectionString = "Data Source=" + dataSource;    connection.Open();    using (SQLiteCommand command = new SQLiteCommand(connection))    {        command.CommandText =            "update Example set Info = :info, Text = :text where ID=:id";        command.Parameters.Add("info", DbType.String).Value = textBox2.Text;         command.Parameters.Add("text", DbType.String).Value = textBox3.Text;         command.Parameters.Add("id", DbType.String).Value = textBox1.Text;         command.ExecuteNonQuery();    }}

So, use the above answer as parameterised SQL is best practice.

But, to answer your question on syntax - there's two issues:

command.CommandText = ("update Example set Info ='" + textBox2.Text + ", Text ='"+textBox3.Text + "where ID ='" + textBox1.Text +"'");

Here, you're not closing the single quote after you've written theset Info ='" + textBox2.Text + ", Text

It should be:set Info ='" + textBox2.Text + "', Text

^^ with a closing ' after the double quote.

You've made same mistake with textBox3.

Also, Text ='"+textBox3.Text + "where

There's no space before the where keyword.

Tip: when having errors like this, output SQL to console & inspect string constructed. But parameterised is best approach.