violates foreign key constraint - postgresql

Question

I keep receiving this error:
insert or update on table "note" violates foreign key constraint "note_username_fkey"
I have two tables: User and Note. Here are the create table statements:
func setup() *sql.DB {
db = connectDatabase()
//Create queries
userTable := `CREATE TABLE IF NOT EXISTS "User"(
UserID SERIAL unique,
UserName VARCHAR(50) PRIMARY KEY,
FirstName VARCHAR(50),
LastName VARCHAR(50),
Password VARCHAR(40)
);`
noteTable := `CREATE TABLE IF NOT EXISTS Note(
NoteID SERIAL PRIMARY KEY,
UserID INT,
UserName VARCHAR(50),
Title VARCHAR(30),
Contents VARCHAR(1000),
DateCreated DATE,
DateUpdated DATE,
FOREIGN KEY (UserName) REFERENCES "User"(UserName)
);`
}
func createNoteInsertSQL(userID string, userName string, title string, content string, selectSetting string) bool {
var newNote Note
var err error
newNote.UserID, err = strconv.Atoi(userID)
if err != nil {
log.Fatal(err)
}
newNote.UserName = userName
newNote.Title = title
newNote.Contents = content
date := time.Now()
newNote.DateCreated = date
newNote.DateUpdated = date
query := `INSERT INTO Note (UserID, UserName, Title, Contents, DateCreated, DateUpdated) VALUES ($1, $2, $3, $4, $5, $6) RETURNING NoteID;`
stmt, err := db.Prepare(query)
if err != nil {
log.Fatal(err)
return false
}
var noteID int
err = stmt.QueryRow(newNote.UserID, newNote.UserName, newNote.Title, newNote.Contents, newNote.DateCreated, newNote.DateUpdated).Scan(&noteID)
if err != nil {
log.Fatal(err)
return false
}
}
Can anyone please tell me where the wrong ?
Thanks.

Answer 1

Check whether "Username" column value you try to insert in note table is already available in "User" table. Because the insert query is trying to insert value that is not available in "User" table.