"generate golang code to add "foo" to every VARCHAR in a SQLITE database".

package main

import (
    "database/sql"
    "fmt"
    "log"

    _ "github.com/mattn/go-sqlite3"
)

func main() {
    // Open SQLite database
    db, err := sql.Open("sqlite3", "your-database-file.db")
    if err != nil {
        log.Fatal(err)
    }
    defer db.Close()

    // Specify the table and column to update
    tableName := "your_table_name"
    columnName := "your_varchar_column_name"

    // Retrieve rows from the table
    rows, err := db.Query(fmt.Sprintf("SELECT rowid, %s FROM %s", columnName, tableName))
    if err != nil {
        log.Fatal(err)
    }
    defer rows.Close()

    // Update VARCHAR columns
    for rows.Next() {
        var rowID int
        var value string

        err := rows.Scan(&rowID, &value)
        if err != nil {
            log.Fatal(err)
        }

        // Append "foo" to the existing value
        newValue := value   "foo"

        // Update the row with the new value
        _, err = db.Exec(fmt.Sprintf("UPDATE %s SET %s = ? WHERE rowid = ?", tableName, columnName), newValue, rowID)
        if err != nil {
            log.Fatal(err)
        }
    }

    fmt.Println("Update complete.")
}

I asked for the database, not for a particular table and column as well.