I am trying to create a number of tables with different names (of course) but sharing the same schema. For this purpose, I am using executemany on a Cursor object as follows:
tables = ['Meanings', 'Synonyms', 'Antonyms', 'Examples', 'Phrases',
'Pronunciations', 'Hyphenations']
create_table_query = '''CREATE TABLE (?) (
id INTEGER NOT NULL,
text TEXT,
word_id INTEGER NOT NULL,
PRIMARY KEY id,
FOREIGN KEY(word_id) REFERENCES Word(id)
)'''
cursor.executemany(create_table_query, tables)
When I execute this snippet, I get the following error message:
OperationalError: near "(": syntax error
I am having trouble fixing the bug here with my SQL since I find the error message to be not descriptive enough. I have tried the following queries but I am unable to develop the understanding of their success and my query's failure:
create_table_query_1 = '''CREATE TABLE {} (
id INTEGER NOT NULL,
text TEXT,
word_id INTEGER NOT NULL,
PRIMARY KEY id,
FOREIGN KEY(word_id) REFERENCES Word(id)
)''' # Syntax error near "id"
create_table_query_2 = '''CREATE TABLE (?) (
id INTEGER PRIMARY KEY,
text TEXT,
word_id INTEGER NOT NULL,
FOREIGN KEY(word_id) REFERENCES Word(id)
)''' # Syntax error near "("
create_table_query_1 = '''CREATE TABLE {} (
id INTEGER PRIMARY KEY,
text TEXT,
word_id INTEGER NOT NULL,
FOREIGN KEY(word_id) REFERENCES Word(id)
)''' # works with string formatting
Also, what are other efficient(in terms of time) ways to achieve the same?
To put my comment into an answer and expand on it: you cannot parametrize table nor column names. I was unable to find any documentation on this...
In a couple of the other examples you have extra parens/brackets that SQLite doesn't need.
So the solution, as you've found, is to use string substitution for the table names as in your final example.
Here's an example with a loop over all of your tables:
for table in tables:
cursor.execute('''CREATE TABLE {} (
id INTEGER PRIMARY KEY,
text TEXT,
word_id INTEGER NOT NULL,
FOREIGN KEY(word_id) REFERENCES Word(id)
)'''.format(table))
I am not completely clear on why you want different tables for the different types of words, though, as this would seem to go against the principles of database design.
Related
I'm basically building a secured online diary application with Flask. However my Python source code returns a syntax error when I try to test the app. I can't detect what's wrong with the syntax. Your help will be appreciated.
I'm attaching a screenshot of the error. And here's my SQL database's schema:
CREATE TABLE users (
id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,
username TEXT NOT NULL,
hash TEXT NOT NULL
);
CREATE TABLE sqlite_sequence(name,seq);
CREATE UNIQUE INDEX username ON users (username);
CREATE TABLE diaries (
id INTEGER PRIMARY KEY AUTOINCREMENT,
user_id INTEGER NOT NULL,
name TEXT NOT NULL,
time TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
title TEXT NOT NULL,
description TEXT NOT NULL,
img_url TEXT,
FOREIGN KEY(user_id) REFERENCES users(id)
);
New error: unsupported value
It is INSERT statement that causes error.
Well, not the insert itself but the way you're using it.
Values should be passed as a tuple (values between "(" and ")")
So, you need to update db.execute line with something like that
db.execute("insert into table_name(col1, col2) values(?, ?)", (col1_val, col2_val))
UPD. regarding the error on second screenshot.
db.execute("Select...) does not return a value but a set of values.
So, you might wanted to use fetchone() as in docs
res = cur.execute('SELECT count(rowid) FROM stocks') # gets you set records
print(res.fetchone()) # get first record
Anyway, check the docs I provided you link to with.
This is the relation I want to create for my quiz app and im using python
Module:
c.execute("""CREATE TABLE Questions (
mod_id INTEGER PRIMARY KEY,
mod_name TEXT NOT NULL
)""")
Question:
c.execute("""CREATE TABLE Questions (
quest_id INTEGER PRIMARY KEY,
quest_name TEXT NOT NULL,
mod_id INTEGER NOT NULL,
FOREIGN KEY (mod_id)
REFERENCES Modules (mod_id)
)""")
Now Since the each feedback correspont to 1 question, how do i sort of create one to one relationship? should I do the same as I did for the question table? would this be handle automatically by sqlite3??
Appreciate all sort of help Thanks!!!
EDIT: Does my feedback table need to have a primary key?? I think no because when accesing the feeback table to delete or add data we just pass the question ID as the parameter to look that row up.
I am trying to create a foreign key to show which homework a student has been set. I have done what I believed to be the right syntax, however I keep getting syntax errors for other parts of the database. I'm not sure if this is because of the foreign key as it hasn't occured otherwise.
c.execute("""CREATE TABLE IF NOT EXISTS HomeworkInfo (
HWID INTEGER PRIMARY KEY AUTOINCREMENT,
HomeworkName text);""")
c.execute("""CREATE TABLE IF NOT EXISTS HomeworkSet (
HWID text,
FOREIGN KEY (HWID) REFERENCES HomeworkInfo(HWID),
FName text,
SName text,
Results text);""")
line 36, in <module>
Results text);""")
OperationalError: near "FName": syntax error
Move the definition of the foreign key at the end of the statement:
CREATE TABLE IF NOT EXISTS HomeworkSet (
HWID text,
FName text,
SName text,
Results text,
FOREIGN KEY (HWID) REFERENCES HomeworkInfo(HWID)
);
or define it like this:
CREATE TABLE IF NOT EXISTS HomeworkSet (
HWID text REFERENCES HomeworkInfo(HWID),
FName text,
SName text,
Results text
);
You can find more about the definition of the foreign keys here: SQLite Foreign Key Support
Just a guess but in your example it looks like HomeworkInfo.HWID is an integer but HomeworkSet.HWID is text. Shouldn't they be the same type?
I've finished making some SQLite tables and am executing the instructions. When executing the instructions, the following error has come up:
sqlite3.OperationalError: near "Category": syntax error
Most of my tables use the same sort of format, below is an example of one such table.
CategoryTableSQL = """ CREATE TABLE IF NOT EXISTS Category(
CategoryID integer PRIMARY KEY AUTOINCREMENT
Category text NOT NULL
);"""
databaseNewTable(Connection, CategoryTableSQL)
You forgot a comma between the declaration of your table fields in your SQL-statement: It should be like this. Always use comma's to seperate the field-creation statements. Except of course, for the last field you create =). Also, I would take care in naming your fields the same name as your tables. To prevent confusion. Just my two cents
CREATE TABLE IF NOT EXISTS Category(
CategoryID integer PRIMARY KEY AUTOINCREMENT,
Category text NOT NULL
);
I think, You just need to add the ',' symbol after the AUTOINCREMENT word. :-)
Like this:
CategoryTableSQL = """ CREATE TABLE IF NOT EXISTS Category(
CategoryID integer PRIMARY KEY AUTOINCREMENT,
Category text NOT NULL
);"""
databaseNewTable(Connection, CategoryTableSQL)
I am using sqlite with python 2.5. I get a sqlite error with the syntax below. I looked around and saw AUTOINCREMENT on this page http://www.sqlite.org/syntaxdiagrams.html#column-constraint but that did not work either. Without AUTO_INCREMENT my table can be created.
An error occurred: near "AUTO_INCREMENT": syntax error
CREATE TABLE fileInfo
(
fileId int NOT NULL AUTO_INCREMENT,
name varchar(255),
status int NOT NULL,
PRIMARY KEY (fileId)
);
This is addressed in the SQLite FAQ. Question #1.
Which states:
How do I create an AUTOINCREMENT
field?
Short answer: A column declared
INTEGER PRIMARY KEY will
autoincrement.
Here is the long answer: If you
declare a column of a table to be
INTEGER PRIMARY KEY, then whenever you
insert a NULL into that column of the
table, the NULL is automatically
converted into an integer which is one
greater than the largest value of that
column over all other rows in the
table, or 1 if the table is empty. (If
the largest possible integer key,
9223372036854775807, then an unused
key value is chosen at random.) For
example, suppose you have a table like
this:
CREATE TABLE t1( a INTEGER PRIMARY
KEY, b INTEGER ); With this table,
the statement
INSERT INTO t1 VALUES(NULL,123); is
logically equivalent to saying:
INSERT INTO t1 VALUES((SELECT max(a)
FROM t1)+1,123); There is a function
named sqlite3_last_insert_rowid()
which will return the integer key for
the most recent insert operation.
Note that the integer key is one
greater than the largest key that was
in the table just prior to the insert.
The new key will be unique over all
keys currently in the table, but it
might overlap with keys that have been
previously deleted from the table. To
create keys that are unique over the
lifetime of the table, add the
AUTOINCREMENT keyword to the INTEGER
PRIMARY KEY declaration. Then the key
chosen will be one more than than the
largest key that has ever existed in
that table. If the largest possible
key has previously existed in that
table, then the INSERT will fail with
an SQLITE_FULL error code.
It looks like AUTO_INCREMENT should be AUTOINCREMENT see http://www.sqlite.org/syntaxdiagrams.html#column-constraint
You could try
CREATE TABLE fileInfo
(
fileid INTEGER PRIMARY KEY AUTOINCREMENT,
name STRING,
status INTEGER NOT NULL
);
We just changed the order from
NOT NULL, AUTO_INCREMENT
to
AUTO_INCREMENT NOT NULL,
an example :
cursor.execute("CREATE TABLE users(\
user_id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,\
user_name VARCHAR(100) NOT NULL)")