SQL (lite) replace string value in all columns with formatting - sql

Question

I'm trying to update a SQLite database with a column "URL" with a specific value. The old url format is "http://www.blz.nl/voster/boek/9789056628512" and the new one is "http://www.blz.nl/voster/boekwinkel/zoeken/?q=9780789327505&oa=true&searchin=taal&taal=dut".
What I am trying to do is replace the url to the new format but keep the value of the 'Q' param from the old url. What is the fastest / best way to achieve this for all columns? I have no idea how to approach this using an SQL query.

Answer 1

You want the SQL?
Basically, you read in the table, search for your keyword, replace it, and write that data back to the database.
Assuming your database name is "mydatabase.db", your code would look something like this (untested):
using Devart.Data.SQLite;
public void Convert()
{
using (var conn = new SQLiteConnection("DataSource=mydatabase.db"))
{
var boek = "//boek//";
var boekwinkel = "//boekwinkel//";
var boek_len = boek.Length;
var table = new DataTable();
var sqlCmd = "SELECT * FROM TableName1;";
conn.Open();
// Read the data into the DataTable:
using (var cmd = new SQLiteCommand(sqlCmd, conn))
{
// The DataTable is ReadOnly!
table.Load(cmd.ExecuteReader());
}
// Use a new SQLiteCommand to write the data.
using (var cmd = new SQLiteCommand("UPDATE TableName1 SET URL=#NEW_URL WHERE URL=#URL;", conn))
{
cmd.Parameters.Add("#URL", SQLiteType.Text, 20);
cmd.Parameters.Add("#NEW_URL", SQLiteType.Text, 20);
foreach (DataRow row in table.Rows)
{
var url = String.Format("{0}", row["URL"]).Trim();
cmd.Parameters["#URL"].SQLiteValue = row["URL"];
if (!String.IsNullOrEmpty(url))
{
var index = url.IndexOf(boek);
if (-1 < index)
{
var first = url.Substring(0, index);
var middle = boekwinkel;
var last = url.Substring(index + boek_len);
var new_url = String.Format("{0}{1}{2}&oa=true&searchin=taal&taal=dut", first, middle, last);
// Place a break point after String.Format.
// Make sure the information being written is correct.
cmd.Parameters["#NEW_URL"].SQLiteValue = new_url;
cmd.ExecuteNonQuery();
}
}
}
}
conn.Close();
}
}