What I would like returned is all the seat_ids in the performance table that have a booking_id that matches all the booking_ids where night = 1 in the booking table - is an INNER JOIN the best way to do it?
Or is it more along the lines of """SELECT seat_id FROM performance WHERE booking_id=(SELECT * FROM booking WHERE night = ?""", (night_number))
With the above I get sqlite3.OperationalError: incomplete input error.
connection = sqlite3.connect('collyers_booking_system.db')
cursor = connection.cursor()
cursor.execute(booking_table)
cursor.execute(performance_table)
connection.commit()
booking_table = """CREATE TABLE IF NOT EXISTS
booking(
booking_id TEXT PRIMARY KEY,
customer_id INTEGER,
night INTEGER,
cost REAL,
FOREIGN KEY (customer_id) REFERENCES customer(customer_id)
)"""
performance_table = """CREATE TABLE IF NOT EXISTS
performance(
performance_id TEXT PRIMARY KEY,
seat_id TEXT,
booking_id INTEGER,
FOREIGN KEY (seat_id) REFERENCES seat(seat_id),
FOREIGN KEY (booking_id) REFERENCES booking(booking_id),
)"""
night_number = 1
cursor.execute("""SELECT seat_id FROM performance INNER JOIN booking ON night=?""", (night_number))
booked_seats = cursor.fetchall()
print(booked_seats)
With this I get ValueError: parameters are of unsupported type error.
First, if this is your actual code, there is a typo in the CREATE statement of the table performance.
You must remove the , at the end of:
FOREIGN KEY (booking_id) REFERENCES booking(booking_id),
Then, here:
cursor.execute("""SELECT seat_id FROM performance WHERE booking_id=(SELECT * FROM booking WHERE night = ?""", (night_number))
you missed a closing parenthesis for the sql statement and the subquery may return more than 1 rows, so instead of = you should use IN.
Also, the parameter night_number should passed as a tuple and not just a number, by adding a , inside the paraentheses:
cursor.execute("""SELECT seat_id FROM performance WHERE booking_id IN (SELECT * FROM booking WHERE night = ?)""", (night_number,))
For the join you need a proper ON clause, that links the tables and a , to create the tuple for night_number:
sql = """
SELECT p.seat_id
FROM performance p INNER JOIN booking b
ON b.booking_id = p. booking_id
WHERE b.night=?
"""
cursor.execute(sql, (night_number,))
Both ways, the operator IN and the join will work.
There is another option which sometimes performs better and this is EXISTS:
sql = """
SELECT p.seat_id
FROM performance p
WHERE EXISTS (
SELECT 1 FROM booking b
WHERE b.night=? AND b.booking_id = p.booking_id
)
"""
cursor.execute(sql, (night_number,))
You are comparing a list result with an integer.
this SELECT * FROM booking WHERE night = ? => returns an N rows
and you are wating for an Integer SELECT seat_id FROM performance WHERE booking_id=?.
You have to use something like this :
SELECT seat_id FROM performance WHERE booking_id in (SELECT * FROM booking WHERE night = ?""", (night_number))
Related
Since the title is quite confusing, allow me to clarify. In this instance, I am trying to select all parentemails of year 10 students. However, the year grade of the students are stored in another table, making the select statement rather tricky.
This is my attempt so far, I hope it highlights the roadblock I am at.
conn = sqlite3.connect('test.db')
c = conn.cursor()
# Makes tables
c.execute(
"""
CREATE TABLE IF NOT EXISTS student (
year INTEGER,
code INTEGER,
PRIMARY KEY (code)
)
""")
c.execute(
"""
CREATE TABLE IF NOT EXISTS studentcontact (
contactcode INTEGER,
studentcode INTEGER,
parentemail TEXT,
PRIMARY KEY (contactcode),
FOREIGN KEY (studentcode) REFERENCES student(code)
)
""")
c.execute("""
INSERT OR REPLACE INTO student (code, year) VALUES
(501, 9),
(502, 10),
(503, 10)
""")
c.execute("""
INSERT OR REPLACE INTO studentcontact (contactcode, studentcode, parentemail) VALUES
(401, 501, "bobjones#email.com"),
(402, 502, "billwilliams#email.com"),
(403, 503, "sallydavidson#email.com")
""")
### -- QUERY HERE -- ##
# My attempt so far
query = """
SELECT code FROM student WHERE year ='10'
SELECT parentemail FROM studentcontact WHERE studentcode = *results from select statement above*
"""
One way to do this is:
SELECT parentemail
FROM studentcontact
WHERE studentcode IN (
SELECT code
FROM student
WHERE year='10'
)
If I understand correctly, you just want join:
SELECT sc.parentemail
FROM student s JOIN
studentcontact sc
ON s.code = sc.studentcode
WHERE s.year = 10
for my code I need to update a record through a users ID number. When the values are entered into an entry box for Exercise and Weight a button is clicked to update the record. Exercises is the first table which has a foreign key ID which is linked to MemberID in the memb table. I have created an UPDATE query for this, this is the code:
def Update(self):
global MemberID
connection = sqlite3.connect(r"E:\TESTING\Program\Accounts.db")
cursor = connection.cursor()
Exercise = self.Exercises.get()
Weight = self.Weights.get()
MemberID = self.ent_MemberID.get()
List = [Exercise, Weight]
cursor.execute("UPDATE Exercises SET Exercise=?, Weight=? WHERE ID = (SELECT MemberID FROM memb WHERE MemberID = ?);",(Exercise, Weight, MemberID))
connection.commit()
It doesn't show any errors but is not entering the data into the table. This is the code I used to create the Exercises table:
CREATE TABLE `Exercises` (
`Exercise` TEXT,
`Weight` INTEGER,
`Reps` INTEGER,
`Sets` INTEGER,
`ID` INTEGER,
PRIMARY KEY(`ID`),
FOREIGN KEY(`ID`) REFERENCES `memb`(`MemberID`)
);
def makeProductTable():
"""This creates a database with a blank table."""
with connect("products.db") as db:
cursor = db.cursor()
cursor.execute("""
CREATE TABLE Product(
ProductID integer,
GTIN integer,
Description string,
StockLevel integer,
Primary Key(ProductID));""")
db.commit()
def editStockLevel():
with connect("products.db") as db:
cursor = db.cursor()
Product_ID=input("Please enter the id of the product you would like to change: ")
Stock_Update=input("Please enter the new stock level: ")
sql = "update product set StockLevel = ('Stock_Update') where ProductID = ('Product_ID');"
cursor.execute(sql)
db.commit()
return "Stock Level Updated."
The first function is used to make the table and it shows my column titles, the second function is needed to update a specific value in the table.
But when this is ran the inputs are executed, however when all show all the products in the table the value for stock level doesn't change.
So I think the problem has something to do with the cursor.execute(sql) line.
Or something like this?
cur.execute("UPDATE Product set StockLevel = ? where ProductID = ?",(Stock_Update,Product_ID))
Yes; you're passing literal strings, instead of the values returned from your input calls. You need to use parameters in the statement and pass thme to the execute call.
sql= "update product set StockLevel = %s where ProductID = %s;"
cursor.execute(sql, (Stock_Update, Product_ID))
[Using Python3.x]
The basic idea is that I have to run a first query to pull a long list of IDs (text) (about a million IDs) and use those IDs in an IN() clause in a WHERE statement in another query. I'm using python string formatting to make this happen, and works well if the number of IDs is small - say 100k - but gives me an error (pyodbc.Error: ('08S01', '[08S01] [MySQL][ODBC 5.2(a) Driver][mysqld-5.5.31-MariaDB-log]MySQL server has gone away (2006) (SQLExecDirectW)')) when the set is indeed about a million IDs long.
I tried to read into it a bit and think it might have something with the default(?) limits set by SQLite. Also I am wondering if I'm approaching this in the right way anyway.
Here's my code:
Step 1: Getting the IDs
def get_device_ids(con_str, query, tb_name):
local_con = lite.connect('temp.db')
local_cur = local_con.cursor()
local_cur.execute("DROP TABLE IF EXISTS {};".format(tb_name))
local_cur.execute("CREATE TABLE {} (id TEXT PRIMARY KEY, \
lang TEXT, first_date DATETIME);".format(tb_name))
data = create_external_con(con_str, query)
device_id_set = set()
with local_con:
for row in data:
device_id_set.update([row[0]])
local_cur.execute("INSERT INTO srv(id, lang, \
first_date) VALUES (?,?,?);", (row))
lid = local_cur.lastrowid
print("Number of rows inserted into SRV: {}".format(lid))
return device_id_set
Step 2: Generating the query with 'dynamic' IN() clause
def gen_queries(ids):
ids_list = str(', '.join("'" + id_ +"'" for id_ in ids))
query = """
SELECT e.id,
e.field2,
e.field3
FROM table e
WHERE e.id IN ({})
""".format(ids_list)
return query
Step 3: Using that query in another INSERT query
This is where things go wrong
def get_data(con_str, query, tb_name):
local_con = lite.connect('temp.db')
local_cur = local_con.cursor()
local_cur.execute("DROP TABLE IF EXISTS {};".format(tb_name))
local_cur.execute("CREATE TABLE {} (id TEXT, field1 INTEGER, \
field2 TEXT, field3 TEXT, field4 INTEGER, \
PRIMARY KEY(id, field1));".format(tb_name))
data = create_external_con(con_str, query) # <== THIS IS WHERE THAT QUERY IS INSERTED
device_id_set = set()
with local_con:
for row in data:
device_id_set.update(row[1])
local_cur.execute("INSERT INTO table2(id, field1, field2, field3, \
field4) VALUES (?,?,?,?,?);", (row))
lid = local_cur.lastrowid
print("Number of rows inserted into table2: {}".format(lid))
Any help is very much appreciated!
Edit
This is probably the right solution to my problem, however when I try to use "SET SESSION max_allowed_packet=104857600" I get the error: SESSION variable 'max_allowed_packet' is read-only. Use SET GLOBAL to assign the value (1621). Then when I try to change SESSION to GLOBAL i get an access denied message.
Insert the IDs into a (temporary) table in the same database, and then use:
... WHERE e.ID IN (SELECT ID FROM TempTable)
I am trying to INSERT or REPLACE INTO t1 if the name is already there. I understand if the id is set then replace will work, but I need it to react to name.
import sqlite3
def insert(name):
cur.execute('INSERT OR REPLACE INTO t1(name) VALUES(?)', [name])
def select():
return cur.execute('SELECT * FROM t1').fetchall()
conn = sqlite3.connect('test')
cur = conn.cursor()
cur.execute('DROP TABLE IF EXISTS t1')
cur.execute('''CREATE TABLE IF NOT EXISTS t1(
id INTEGER PRIMARY KEY,
name TEXT NOT NULL
)''')
insert('jack')
insert('jack')
insert('jack')
print select()
output
[(1, u'jack'), (2, u'jack'), (3, u'jack')]
INSERT or REPLACE ... will do replace only if there are collisions. And as your name column isnt collidable, this event cannot accur (at least not on name). You need to make name collidable:
CREATE UNIQUE INDEX IF NOT EXISTS iname ON t1 (name)
Also note that you dont need to have id column, because sqlite3 has ROWID on every table.