i made a project which collects data from user and store it on different tables, the application has a delete function which the first option is to delete a specific table which is i already did and the second one is to delete all existing tables.
How can i drop all tables inside my database?
so this is my variables.
conn = sqlite3.connect('main.db')
cursor = conn.execute("DROP TABLE")
cursor.close()
How can i drop all tables inside my database?
According to sqlitetutorial.net
SQLite allows you to drop only one table at a time. To remove multiple
tables, you need to issue multiple DROP TABLE statements.
You can do it by querying all table names (https://www.sqlite.org/faq.html#q7)
Then you can use the result to delete the tables one by one
Here is the code, the function delete_all_tables does that
TABLE_PARAMETER = "{TABLE_PARAMETER}"
DROP_TABLE_SQL = f"DROP TABLE {TABLE_PARAMETER};"
GET_TABLES_SQL = "SELECT name FROM sqlite_schema WHERE type='table';"
def delete_all_tables(con):
tables = get_tables(con)
delete_tables(con, tables)
def get_tables(con):
cur = con.cursor()
cur.execute(GET_TABLES_SQL)
tables = cur.fetchall()
cur.close()
return tables
def delete_tables(con, tables):
cur = con.cursor()
for table, in tables:
sql = DROP_TABLE_SQL.replace(TABLE_PARAMETER, table)
cur.execute(sql)
cur.close()
SQLite3 code to issue multiple DROP TABLE statements based on TEMP_% name wildcard:
.output droptables.sql
SELECT "DROP TABLE """|| sqlite_master.name ||""";" FROM sqlite_master
WHERE type = "table" AND sqlite_master.name LIKE 'TEMP_%';
.read droptables.sql
Example result in .sql output file:
DROP TABLE "TEMP_table1";
DROP TABLE "TEMP_table2";
DROP TABLE "TEMP_table3";
...
Python3 to paste SQL into:
conn = sqlite3.connect(f"main.db")
conn.row_factory = sqlite3.Row
dbc = conn.cursor()
dbc.execute(
f"DROP TABLE 'TEMP_table1';"
)
conn.commit()
Related
I am running this script and want to create a table by passing values in psql query using variables. So, that I can create multiple table in one go. But this cur.execute("CREATE TABLE IF NOT EXISTS(%s, %s)",[table_name, comp_schema]) line is throwing error. How can I write this query to create a table with the given schema?
import psycopg2
conn = psycopg2.connect(database="review_check", user = "xxx", password = "xxx",)
cur = conn.cursor()
print ("Opened database successfully")
comp_schema = """
as_of_date DATE PRIMARY KEY NOT NULL,
verified_reviews INTEGER,
lsa_total_reviews INTEGER
"""
table_name = 'comp_first'
cur.execute("CREATE TABLE IF NOT EXISTS(%s, %s)",[table_name, comp_schema])
conn.commit()
conn.close()
Use the psycopg2.sql module to compose a query dynamically. see https://www.psycopg.org/docs/sql.html.
There's a couple of errors here, in both the SQL syntax and the Python:
cur.execute("CREATE TABLE IF NOT EXISTS(%s, %s)",[table_name, comp_schema])
should be
cur.execute("CREATE TABLE IF NOT EXISTS %s (%s)"%(table_name, comp_schema))
It might be easier during development to build the query in a separate variable first, then print it to see if it looks right:
test = "CREATE TABLE IF NOT EXISTS %s (%s)"%(table_name, comp_schema)
print(test)
>>CREATE TABLE IF NOT EXISTS comp_first (
as_of_date DATE PRIMARY KEY NOT NULL,
verified_reviews INTEGER,
lsa_total_reviews INTEGER
)
I try to import data from a oracle database to a pandas dataframe.
right Now i am using:
import cx_Oracle
import pandas as pd
db_connection_string = '.../A1#server:port/servername'
con = cx_Oracle.connect(db_connection_string)
query = """SELECT*
FROM Salesdata"""
df = pd.read_sql(query, con=con)
and get the following error: DatabaseError: ORA-00942: Table or view doesn't exist
When I run a query to get the list of all tables:
cur = con.cursor()
cur.execute("SELECT table_name FROM dba_tables")
for row in cur:
print (row)
The output looks like this:
('A$',)
('A$BD',)
('Salesdata',)
What I am doing wrong? I used this question to start.
If I use the comment to print(query)I get:
SELECT*
FROM Salesdata
Getting ORA-00942 when running SELECT can have 2 possible causes:
The table does not exist: here you should make sure the table name is prefixed by the table owner (schema name) as in select * from owner_name.table_name. This is generally needed if the current Oracle user connected is not the table owner.
You don't have SELECT privileges on the table. This is also generally needed if the current Oracle user connected is not the table owner.
You need to check both.
I write a python code to create a table,but when I open DB browser for SQLite, it does not the table I have created, I am new to database, so can anyone tell me what is wrong with it ? Many thanks!
import sqlite3
conn = sqlite3.connect('test1.sqlite')
cur = conn.cursor()
cur.execute('''
DROP TABLE IF EXISTS Test''')
cur.execute('''
CREATE TABLE Test (azaz TEXT, count INTEGER)''')
cur.execute('''INSERT INTO Test (azaz, count)
VALUES ( 'aa', 1 )''' )
conn.commit()
conn.close()
image link:imgur.com/epfar.png
Your code is right and if you try:
import sqlite3
conn = sqlite3.connect('test1.sqlite')
row = conn.execute('SELECT * FROM Test').fetchone()
print("azaz=", row[0])
print("count=", row[1])
You will see this output:
('azaz=', u'aa')
('count=', 1)
So the table has been created and values has been inserted in the table.
I have just tested your code and it works flawlessly. I have used python-3.5 and DB Broswer for sqlite, tested on window 7 pro.
I have just started using MySQLdb in python. I am able to create table but when I try to insert, no rows are inserted into the table and its shows that table is still empty.
import MySQLdb
db = MySQLdb.connect("localhost","root","shivam","test")
cursor = db.cursor()
s = "DROP TABLE IF EXISTS batting"
cursor.execute(s)
s = """create table batting (
name varchar(50) primary key,
matches integer(5),
innings integer(5),
runs integer(5),
highest integer(3),
strikerate integer(3),
hundreds integer(3),
fifties integer(3)
)"""
cursor.execute(s)
s = """insert into batting(name) values(
"shivam")"""
cursor.execute(s)
db.close()
Where I could be going wrong?
You forgot to commit your connection. Simply add:
cursor.execute(s)
db.commit()
Have a look at this. It explains why you need to commit
I am using sqlite for the first time. I used Xammp before. Now I have a scene here. Each time I run the code below, records don't just get appended at the end of the table rather the table is created new and thus it's working just like a console.
Can any one tell me what I am doing wrong here?
import sqlite3
db = sqlite3.connect('test.db')
db.row_factory = sqlite3.Row
db.execute('drop table if exists test')
db.execute('create table test (t1 text,i1 text)')
db.execute('insert into test (t1, i1) values (?, ?)',('xyzs','51'))
cursor = db.execute('select * from test')
for row in cursor:
print(row['t1'],row['i1'])
First, you need to execute commands on a cursor and not the connection itself. Second, you need to commit your transactions:
import sqlite3
db = sqlite3.connect('test.db')
db.row_factory = sqlite3.Row
cur = db.cursor() # getting a cursor
cur.execute('drop table if exists test')
cur.execute('create table test (t1 text,i1 text)')
db.commit() # commit the transaction, note commits are done
# at the connection, not on the cursor
cur.execute('insert into test (t1, i1) values (?, ?)',('xyzs','51'))
db.commit()
cursor = cur.execute('select * from test')
for row in cursor:
print(row['t1'],row['i1'])
Please have a look at the documentation. This will help you once you start working with other databases in Python because they all follow the same API.
This line drops the old table:
db.execute('drop table if exists test')
And this one creates a new table:
db.execute('create table test (t1 text,i1 text)')
That should explain your problem. Remove these two lines and you'll be fine - But create the table first separately.