How do i get user details to autofill into entry boxes after i get them from my sql database

I have an entry form; when the user types in their username and presses the button, I want it to autofill with their details from the sql database. I know you need to use state=DISABLED, if im correct, but I dont know how to use this.

self.userentered=StringVar()

        #fill out entry form
        Label(self.master,text="Final steps to entering your race...",font=(20),fg="blue").place(x=10,y=10)

        Label(self.master,text="Username:",width=20).place(x=10,y=50)
        self.userentry=Entry(self.master,textvariable=self.userentered)
        self.userentry.place(x=160,y=50)
        Button(self.master,text="Search Details",command=self.searchnames,width=15).place(x=300,y=50)

db=sqlite3.connect('project races.db')
        cursor = db.cursor()
        u = self.userentered.get()
        sql = "SELECT Name from AthleteDetails where username = ?"
        cursor.execute(sql,(u,))
        name = cursor.fetchone()

        sql = "SELECT DOB from AthleteDetails where username = ?"
        cursor.execute(sql,(u,))
        dob = cursor.fetchone()

        sql = "SELECT Gender from AthleteDetails where username = ?"
        cursor.execute(sql,(u,))
        gender = cursor.fetchone()

        sql = "SELECT Email from AthleteDetails where username = ?"
        cursor.execute(sql,(u,))
        email = cursor.fetchone()

        sql = "SELECT Club from AthleteDetails where username = ?"
        cursor.execute(sql,(u,))
        club = cursor.fetchone()

Label(self.master,text="Full Name",width=20).place(x=10,y=70)
        self.nameentry=Entry(self.master,textvariable=name,state=DISABLED)
        self.nameentry.place(x=150,y=70)

        Label(self.master,text="Date of Birth",width=20).place(x=10,y=90)
        self.dobentered = Entry(self.master,textvariable=dob,state=DISABLED)
        self.dobentered.place(x=150,y=90)

        Label(self.master,text="Gender",width=20).place(x=10,y=110)
        self.genderBox = Entry(self.master,textvariable=gender,state=DISABLED)
        self.genderBox.place(x=150,y=110)
    
        Label(self.master,text="Club",width=20).place(x=10,y=130)
        self.clubentry=Entry(self.master,textvariable=club,state=DISABLED)
        self.clubentry.place(x=150,y=130)

        Label(self.master,text="Email",width=20).place(x=10,y=150)
        self.emailentry=Entry(self.master,textvariable=email,state=DISABLED)
        self.emailentry.place(x=150,y=150)
        
        Label(self.master,text="Time prediction:",font=(14)).place(x=10,y=170)
        time = StringVar()
        self.timeentry=Entry(self.master,textvariable=time)
        self.timeentry.place(x=150,y=170)
        Label(self.master,text="*To nearest minute",font=(12)).place(x=300,y=170)

I want the entry boxes to be filled with the users data

Change the state to normal, insert the data using the widget's insert method, then change it back to disabled.

self.nameentry.configure(state="normal")
self.nameentry.delete(0, "end")  # only necessary if it previously had a value
self.nameentry.insert(0,name)
self.nameentry.configure(state="disabled")

Note that name, dob, gender, email and club may be None (no record found in database) or a tuple (record found in database). They are not instances of StringVar(), so using them as textvariable option of Entry widget will not update the widgets automatically.

Also you can use one SQL query to fetch all of them instead of five SQL queries, and then create those instances of StringVar() with the result of SQL query as below:

db = sqlite3.connect('project races.db')
cursor = db.cursor()
u = self.userentered.get()
# use single SQL query to get all the information
sql = "SELECT Name, DOB, Gender, Email, Club FROM AthleteDetails WHERE username = ?"
cursor.execute(sql, (u,))
result = cursor.fetchone()
if result:
    # create required StringVar and set their values
    name = StringVar(value=result[0])
    dob = StringVar(value=result[1])
    gender = StringVar(value=result[2])
    email = StringVar(value=result[3])
    club = StringVar(value=result[4])

    # user details
    Label(self.master,text="Full Name",width=20).place(x=10,y=70)
    self.nameentry=Entry(self.master,textvariable=name,state=DISABLED)
    self.nameentry.place(x=150,y=70)

    Label(self.master,text="Date of Birth",width=20).place(x=10,y=90)
    self.dobentered = Entry(self.master,textvariable=dob,state=DISABLED)
    self.dobentered.place(x=150,y=90)

    Label(self.master,text="Gender",width=20).place(x=10,y=110)
    self.genderBox = Entry(self.master,textvariable=gender,state=DISABLED)
    self.genderBox.place(x=150,y=110)

    Label(self.master,text="Club",width=20).place(x=10,y=130)
    self.clubentry=Entry(self.master,textvariable=club,state=DISABLED)
    self.clubentry.place(x=150,y=130)

    Label(self.master,text="Email",width=20).place(x=10,y=150)
    self.emailentry=Entry(self.master,textvariable=email,state=DISABLED)
    self.emailentry.place(x=150,y=150)

    Label(self.master,text="Time prediction:",font=(14)).place(x=10,y=170)
    time = StringVar()
    self.timeentry=Entry(self.master,textvariable=time)
    self.timeentry.place(x=150,y=170)
    Label(self.master,text="*To nearest minute",font=(12)).place(x=300,y=170)