我想获得第二高的样本日期并得到以下错误，请让我知道我在哪里做错了
(SELECT* FROM resheader WHERE sampledate =
(SELECT MAX(sampleDate) FROM resheader
WHERE sampleDate < (SELECT MAX(sampleDate) FROM resheader)
)
) as 'Previous Sample'
错误
Msg 116，Level 16，State 1，Line 12只有一个表达式 在未引入子查询时在选择列表中指定 存在。
答案 0 :(得分：1)
在SQL Server 2012中，您可以使用code ref子句获取第二行（按所需条件排序后）：
import Tkinter as tk
import ttk
import os
LARGE_FONT = ("Verdana", 12)
NORM_FONT = ("Verdana", 10)
SMALL_FONT = ("Verdana", 8)
def center(win):
"""
centers a tkinter window
param win: the window to center on the screen
"""
win.update_idletasks()
width = win.winfo_width()
frm_width = win.winfo_rootx() - win.winfo_x()
win_width = width + 2 * frm_width
height = win.winfo_height()
titlebar_height = win.winfo_rooty() - win.winfo_y()
win_height = height + titlebar_height + frm_width
x = win.winfo_screenwidth() // 2 - win_width // 2
y = win.winfo_screenheight() // 2 - win_height // 2
win.geometry('{}x{}+{}+{}'.format(width, height, x, y))
win.deiconify()
def popupmsg(msg):
popup1 = tk.Tk()
center(popup1)
popup1.minsize(width=60, height=70)
popup1.maxsize(width=60, height=70)
popup1.wm_title("Attention!")
label = ttk.Label(popup1, text=msg, font=NORM_FONT, anchor="center")
label.pack(side="top", fill="x", pady=10)
b1 = ttk.Button(popup1, text="Ok", command=lambda: popup1.destroy())
b1.pack()
popup1.mainloop()
class Testapp(tk.Tk):
def __init__(self, *args, **kwargs):
tk.Tk.__init__(self, *args, **kwargs)
tk.Tk.iconbitmap(self, default="testappicon2.ico")
tk.Tk.wm_title(self, "Psychoacoustic Tests")
container = ttk.Frame(self)
container.pack(side="top", fill="both", expand=True)
container.grid_columnconfigure(0, weight=1)
container.grid_rowconfigure(0, weight=1)
menubar = tk.Menu(container)
filemenu = tk.Menu(menubar, tearoff=0)
filemenu.add_separator()
filemenu.add_command(label="Exit", command=lambda: self.destroy())
menubar.add_cascade(label="File", menu=filemenu)
tk.Tk.config(self, menu=menubar)
self.frames = {}
for F in (Startpage, TestSelect, Test1):
frame = F(container, self)
self.frames[F] = frame
self.minsize(width=900, height=500)
frame.grid(row=0, column=0, sticky="nsew")
self.show_frame(Startpage)
def show_frame(self, cont):
frame = self.frames[cont]
frame.tkraise()
class Startpage(ttk.Frame):
def __init__(self, parent, controller):
ttk.Frame.__init__(self, parent)
self.controller = controller
self.titlelabel = ttk.Label(self, text="User Information", font = LARGE_FONT)
self.titlelabel.grid(row=0, column=0, columnspan=4, padx = 10, pady = 10)
self.firstnamelabel = ttk.Label(self, text="First Name: ", font = NORM_FONT)
self.firstnamelabel.grid(row=1, column=0, sticky = 'w', padx = 15, pady = 10)
self.lastnamelabel = ttk.Label(self, text="Last Name: ", font = NORM_FONT)
self.lastnamelabel.grid(row=2, column=0, sticky = 'w', padx = 15, pady = 10)
self.firstnameentry = ttk.Entry(self)
self.firstnameentry.grid(row=1, column=1, padx=5, sticky = 'we', columnspan = 3)
self.lastnameentry = ttk.Entry(self)
self.lastnameentry.grid(row=2, column=1, padx=5, sticky = 'we', columnspan = 3)
self.birthdaylabel = ttk.Label(self, text="Birthday: ", font = NORM_FONT)
self.birthdaylabel.grid(row=3, column=0, sticky = 'w', padx = 15, pady = 10)
self.daydropdown = ttk.Combobox(self, justify='center', height=20, width=2,
values = (1,2,3,4,5,6,7,8,9,10,11,12,13,14,
15,16,17,18,19,20,21,22,23,24,25,
26,27,28,29,30,31),
state='readonly')
self.daydropdown.grid(row=3, column=1, padx = 3, sticky = 'ew')
self.monthdropdown = ttk.Combobox(self, justify='center', height=12, width=10,
values = ('January','Feburary','March',
'April','May','June','July',
'August','September','October',
'November','December'),
state='readonly')
self.monthdropdown.grid(row=3, column=2, padx=3, sticky = 'ew')
self.yeardropdown = ttk.Combobox(self, justify='center', height=20, width=4,
values = (1980, 1981, 1982, 1983, 1984,
1985, 1986, 1987, 1988, 1989,
1990, 1991, 1992, 1993, 1994,
1995, 1996, 1997, 1998, 1999),
state = 'readonly')
self.yeardropdown.grid(row=3, column=3, padx = 3, sticky = 'ew')
self.genderlabel = ttk.Label(self, text="Gender: ", font = NORM_FONT)
self.genderlabel.grid(row=4, column=0, sticky = 'w', padx = 15, pady = 10)
self.var = tk.IntVar()
self.Maleradio = ttk.Radiobutton(self, text='Male', variable=self.var, value = 1)
self.Maleradio.grid(row=4, column=1, sticky = 'w')
self.Femaleradio = ttk.Radiobutton(self, text='Female', variable=self.var, value = 2)
self.Femaleradio.grid(row=5, column=1, sticky = 'w')
self.emaillabel = ttk.Label(self, text="Email: ", font = NORM_FONT)
self.emaillabel.grid(row=6, column=0, sticky = 'w', padx = 15, pady = 10)
self.emailentry = ttk.Entry(self)
self.emailentry.grid(row=6, column=1, columnspan=3, sticky='ew')
self.experiencelabel = ttk.Label(self, text="Musical Experience: ", font = NORM_FONT)
self.experiencelabel.grid(row=7, column=0, sticky = 'w', padx = 15, pady = 10)
self.expdropdown = ttk.Combobox(self, justify='center', height=3, width=17,
values = ('No experience', 'Some experience',
'Musician level'), state='readonly')
self.expdropdown.grid(row=7, column=1, columnspan=3, sticky = 'w')
self.button1 = ttk.Button(self, text="To Tests", command= lambda: self.checkempty())
self.button1.grid(row=8, column=3)
def shortcut():
controller.show_frame(TestSelect)
buttonshort = ttk.Button(self, text="To Tests shortcut", command= lambda: shortcut())
buttonshort.grid(row=9, column=3)
def get_info(self):
Name = self.firstnameentry.get()
Surname = self.lastnameentry.get()
Day = self.daydropdown.get()
Month = self.monthdropdown.get()
Year = self.yeardropdown.get()
foldername = (str(Name[0]) + str(Surname[0]) +
str(Day) + "_" + str(Month) + "_" +
str(Year))
return foldername
def create_directory(self):
if not os.path.isdir(self.get_info()):
directory = "C:\Users\Rylan\Documents\Python\Basel Summerintern files\{}".format(self.get_info())
os.makedirs(directory)
datafile = "{}_userinfo.txt".format(self.get_info())
entirefile = os.path.join(directory, datafile)
myfile = open(entirefile, 'w')
myfile.write(self.userinfo())
myfile.close()
self.controller.show_frame(TestSelect)
else:
popupmsg("Folder already exists")
def userinfo(self):
Name = self.firstnameentry.get()
Surname = self.lastnameentry.get()
Day = self.daydropdown.get()
Month = self.monthdropdown.get()
Year = self.yeardropdown.get()
Email = self.emailentry.get()
Experience = self.expdropdown.get()
def genderget():
Gender = self.var.get()
if Gender == 1:
UserGender = "Male"
elif Gender == 2:
UserGender = "Female"
return UserGender
user_info = ("Participant Name: " + str(Name) + " " +
str(Surname) + "\nBirthday: " + str(Day) + "_" +
str(Month) + "_" + str(Year) + "\nGender: " +
str(genderget()) + "\nEmail: " + str(Email) +
"\nMusical Experience: " + str(Experience) +
"\nDirectory Name: " + str(self.get_info()))
return user_info
def checkempty(self):
Name = self.firstnameentry.get()
Surname = self.lastnameentry.get()
Day = self.daydropdown.get()
Month = self.monthdropdown.get()
Year = self.yeardropdown.get()
Email = self.emailentry.get()
Experience = self.expdropdown.get()
if len(Name) == 0:
popupmsg("Please complete the user information form")
elif len(Surname) == 0:
popupmsg("Please complete the user information form")
elif Day == None:
popupmsg("Please complete the user information form")
elif Month == None:
popupmsg("Please complete the user information form")
elif Year == None:
popupmsg("Please complete the user information form")
elif self.var.get() == 0:
popupmsg("Please complete the user information form")
elif len(Email) == 0:
popupmsg("Please complete the user information form")
elif Experience == None:
popupmsg("Please complete the user information form")
else:
self.create_directory()
class TestSelect(ttk.Frame):
def __init__(self, parent, controller):
ttk.Frame.__init__(self, parent)
self.controller = controller
label = ttk.Label(self, text="Select tests", font = LARGE_FONT)
label.grid(row=0, column=0, columnspan=3)
Test1Button = ttk.Button(self, text="Do test 1", command=lambda: controller.show_frame(Test1))
Test1Button.grid(row=1, column=0, padx = 20, pady = 15, sticky = 'nsew')
button2 = ttk.Button(self, text="Home", command=lambda: controller.show_frame(Startpage))
button2.grid(row=3, column=2)
class Test1(ttk.Frame):
def __init__(self, parent, controller):
ttk.Frame.__init__(self, parent)
self.controller = controller
label = ttk.Label(self, text="Test 1", font = LARGE_FONT)
label.grid(row=0, column=0, columnspan=2)
button2 = ttk.Button(self, text="Page one", command=lambda: controller.show_frame(TestSelect))
button2.grid(row=1, column=0, sticky = "w")
yesbutt1 = ttk.Button(self)
yesbutt1.grid(row=2, column=0)
nobutt1 = ttk.Button(self)
nobutt1.grid(row=2, column=1)
yesbutt1['text'] = "Yes: 0"
nobutt1['text'] = "No: 0"
self.nobttn_clicks = 0
self.yesbttn_clicks = 0
def update_countyes():
if self.yesbttn_clicks >= 1 or self.nobttn_clicks >= 1:
popupmsg("Only one answer allowed!")
else:
self.yesbttn_clicks += 1
yesbutt1['text'] = "Yes: " + str(self.yesbttn_clicks)
directory = "C:\Users\Rylan\Documents\Python\Basel Summerintern files\{}".format(self.get_t_info())
datafile = "{}_test1data.txt".format(self.get_t_info())
entirefile = os.path.join(directory, datafile)
myfile = open(entirefile, 'a')
myfile.write('\nyes')
myfile.close()
def update_countno():
if self.yesbttn_clicks >= 1 or self.nobttn_clicks >= 1:
popupmsg("Only one answer allowed!")
else:
self.nobttn_clicks += 1
nobutt1['text'] = "No: " + str(self.nobttn_clicks)
directory = "C:\Users\Rylan\Documents\Python\Basel Summerintern files\{}".format(self.get_t_info())
datafile = "{}_test1data.txt".format(self.get_t_info())
entirefile = os.path.join(directory, datafile)
myfile = open(entirefile, 'a')
myfile.write('\nno')
myfile.close()
yesbutt1['command'] = update_countyes
nobutt1['command'] = update_countno
def get_t_info(self):
self.gettheinfo = Startpage(app, self.controller).get_info()
return self.gettheinfo
app = Testapp()
app.mainloop()
答案 1 :(得分：0)
这样做怎么样？如果我们假设所有日期都是唯一的：
SELECT rh.*
FROM resheader rh
ORDER BY sampleDate DESC
LIMIT 1, 1;
如果它们不是唯一的，那么：
SELECT rh.*
FROM resheader rh
WHERE sampledate = (SELECT DISTINCT SampleDate
FROM resheader
ORDER BY sampleDate DESC
LIMIT 1, 1
);
答案 2 :(得分：0)
如果您的SQL Server版本不支持FETCH OFFSET（2012及以上版本）。您可以使用排名函数来实现：
SELECT T.sampledate
FROM (
SELECT DENSE_RANK() OVER (ORDER BY sampledate DESC) AS RN, *
FROM resheader
) AS T
WHERE T.RN = 2;