Python multiple cursors for one connection Jun 9, 2015 · Previous Answer: To insert multiple rows, using the multirow VALUES syntax with execute() is about 10x faster than using psycopg2 executemany(). connect('connection_string') cursor_hostname = connection_hostname. 243. However, in my anecdotal experience, if I didn't close the cursor explicitly, the memory usage of the process would grow without bounds -- this might have something to do with my usage of a custom rowfactory, where I had to capture the cursor in a lambda May 17, 2015 · Python, sharing mysql connection in multiple functions - pass connection or cursor? 1 Python / mysql. args[1]) Mar 9, 2021 · Python cursor class methods fetchall, fetchmany(), fetchone() to retrieve rows from a database table to read SQLite, MySQL, PostgreSQL and relational database table Feb 12, 2019 · The __init__ method reads database configurations from an INI file in order to call the connection and set two dictionaries, one for connections and one for cursors. Sep 11, 2014 · In your situation, the most direct solution would be to open a second connection to use while iterating over the result set of the unbuffered query. The timeout parameter specifies how long the connection should wait for the lock to go away until raising an exception. Oct 17, 2019 · I am trying to create a table via pymssql, but I am getting the error: InterfaceError: Connection is closed. Create MySQL Cursor Function with Python. SQL_DB, conv=convt, use_unicode=True, charset="utf8") return conn def requestCursor(conn): return conn. Feb 23, 2018 · I have created multiple python classes to hold various windows (one class per window) , and inside every class I need to 1) perform SELECT statements on database A , 2) perform SELECT/INSERT/INSERT OR UPDATE statements on database B. I defined the connection object as a single time and pas May 18, 2012 · PEP-249, where DBApi 2. 31 python mysqldb multiple cursors for one connection. Of course that's more than fine. cursor() cursor_db_2 = connect_db_2. It is an object that is used to make the connection for executing SQL queries. 2. Aug 12, 2010 · Is there a way to accept input from more than one mouse separately? I'm interested in making a multi-user application and I thought it would be great if I could have 2 or more users holding wireles I am opening mysql connection in the main function and use that connection in multiple functions called by the main function. PYTHON : python mysqldb multiple cursors for one connectionTo Access My Live Chat Page, On Google, Search for "hows tech developer connect"I promised to shar Oct 8, 2023 · The clientsocket. In the OP's question, this would be cursor1: cursor1 = db. close() What is the difference between a connection to a database and a cursor? Is there any downside of having an open connection (for example, for a few minutes?). cursor; Then start multiple threads or processes sharing the cursor; In every thread (or process) I will select the data from the database (the same table) by chunks I have a python program that calls a stored procedure from db2 database. Usually, one have his script connect to the DB via a client DB-API (like psycopg2 or MySQLdb): connection = psycopg2. execute() method is at the core of Python‘s database connectivity powers. Which is why you would not have issues in multiprocessing, since each process will be creating its own connection. ON THE OTHER HAND, if what you have is working, it's really hard to argue with success. 0b1. Cursor. One aspect of this management is knowing when to close the connection and when to close the cursor. cursor() # Fetching records for which I need to initiate a class instance cur. As such, you won't see any improvement by having multiple cursors in a single connection. It serves as an intermediary between your Python code and the SQLite database. I have already tried to put the CREATE TABLE statement into the same connection with Jun 5, 2012 · cursor = connection. Aug 3, 2014 · This is how I have my MySQLdb setup. NB i want to clerify that i know i can have more than one connection and i know for sure that it's Feb 1, 2014 · Basically with the program as a procedural script I just had to create one DB, one connection and one cursor, which could be shared by all the functions in the script: conn = sqlite3. 7. Connection, that <module>. Following MVC in python :) One DBConnection class Aug 2, 2018 · You have to open multiple connections. Feb 16, 2022 · In this article, we are going to discuss cursor objects in sqlite3 module of Python. org Create a second connection. JS there is this library that extends the original one and add a method call "ExecutionAll" to it: snowflake-multisql Feb 17, 2017 · I use python every day with a heavy emphasis on database work. g. Executing multiple transactions (as opposed to just SQL statements), looks like this: Feb 21, 2016 · Using Connector/Python you have to use the buffered-argument set to True for cursor you use as iterator. SQL_PORT, user=c. 13, 3. after inserting rows should we use connection. connect() cur=con. to replace: import psycopg2 def connector(): re Nov 9, 2017 · I think it can be done like this: sqlQuery = "SELECT a. pyval from table1 as a, (select t1. Is there anything wrong with passing cursor from main function instead Nov 11, 2011 · def getDatabaseResult(sqlQuery,connectioninfohere): # connect to the database vDatabase = MySQLdb. 3 and 3. fetchall(). Cursor, and <module>. 13', 'mark', '********', 'dex'); cur = con. execute() method is designed take only one statement, because it makes guarantees about the state of the cursor afterward. DictCursor) Jun 6, 2013 · Python includes the sqlite3 module, which makes this a snap. It will keep the result set in the server (MySQL data structure), rather than transfer the result set to the client (Python data structure) which is what the default cursor does. text_factory = sqlite3. execute(my_insert_statement) connection. SQL_HOST, port=c. app. Remember that your backend here is a highly tuned professional database system, engineered for large volume simultaneous use. The __enter__ method takes the specified database connection and cursor returning at the end the cursor to execute queries. execute() and use the cursor as an iterator. This specification is Sep 12, 2021 · I am currently working on a huge project, which constantly executes queries. cursor() Now you can execute your query with cursor. Each thread (http request processor) picks up a connection from the pool when it needs it and then returns it back to the pool when done. Now I was wondering: Is it sufficient to close the connection by doing: connection. PYTHON : Can I use multiple cursors on one connection with pyodbc and MS SQL Server?To Access My Live Chat Page, On Google, Search for "hows tech developer c Mar 18, 2022 · I am opening a cursor with connection. Sep 23, 2014 · Try using a MySQL SSCursor. Jul 9, 2018 · Firstly, I'd suggest creating a new connection for each thread created. execute("SET NAMES utf8") cursor. cursor() conn. py. import MySQLdb import MySQLdb. If you check the docs on Python sqlite module, you can see that a python module cursor is needed even for a CREATE TABLE statement, so it's used for cases where a mere connection object should suffice - as correctly pointed out by the OP. execute('delete from table_b') finally: c. I am using results = cursor. projectid where t1. The result set still remains and can be looped through. Execute the SELECT query using the cursor. fetchone() print "Database version : %s " % ver. close() and cursor. in Python: cursor. Context managers and the with statement are an easy way to ensure a cursor and a connection are closed when no longer required. Sep 24, 2009 · I think you have roughly the right architecture -- presenting it in terms of "cursors" WILL confuse the "old SQL hands", because they'll be thinking of the many issues connected with DECLARE foo CURSOR, FETCH FROM CURSOR, WHERE CURRENT OF CURSOR, and other such beauts having to do with SQL cursors. What I am wondering is how should I organize connection objects and cursors. cursor() method: they are bound to the connection for the entire lifetime and all the commands are executed in the context of the database session wrapped by the connection. close() after the while True: in the function and the s. You don't need a new connection, however. Would appreciate any feedback. MySQL (and other's) perform Jun 23, 2014 · @AlexanderYau - Because the connection is not explicitly designed to be used from multiple processes (as in this case) the processes using that connection need to synchronize all accesses to that connection correctly for it to work, with probably significant overhead, probably more then just creating a new connection. execute(qry2). cursor() cursor. Jul 9, 2015 · import mysql. cityid in ( SELECT cityid FROM <tbl3> WHERE cbdid ="+cbdid+" group by cityid) and t1. Define the SELECT query. execute() method. Thus, having multiple cursors connected to the same database can lead to better resource management, allowing different queries to run in parallel. and 3. connect(database_connection_string) as conn: with conn. but when doing those 2 lines as seperate executes in a cursor, it forgets what '@hi' is, by the time I've executed my second statement, which I don't get. I want to fetch the data for multiple table. 6. execute('COMMIT')) affect transactions in progress on another cursor within the same connection? Aug 23, 2019 · import psycopg2 #Create connection con=psycopg2. connect(connection_string) qry1 = "Select * FROM Table1" rows = cursor. Following is the syntax for the cursor. execute(SQLtype1, rowToInsert) cursor. In short, I'm trying to open a single MySQL connection and share it with multiple threads, so that each thread creates and uses a cursor, allowing a second query to be placed before the end of the first query. WRT to making multiple connections, just make another the same way you made the first one: conn = psycopg2. execute("query") See full list on geeksforgeeks. use the fetchall() method of the cursor to recover all the results before beginning another query: Using multiple cursors in Python to interact with MySQL can be done with the MySQLdb library. connect( cursor_factory=MixinLoggedDictCursor, connection_factory=LoggingConnection, **kwargs ) conn. Practical Example of Using Cursors Feb 1, 2021 · from database import DB DB(). You can also combine the daily and monthly stats if you want, with a UNION ALL. Python MySQLdb handle multiple cursors: Command out of sync. cursor = connection. So a typical program works with multiple cursor handles for parallel operations. Feb 14, 2009 · WARNING: The Python docs have this to say about the check_same_thread option: "When using multiple threads with the same connection writing operations should be serialized by the user to avoid data corruption. Cursors are especially useful when executing queries that may yield data from the database such as those involving the SELECT sql command. There is nothing in pyodbc (or pypyodbc) to prevent you from passing a string containing an anonymous code block to the Cursor. Can I use multiple cursors on one connection with pyodbc and MS SQL Server? 3. The cursor. Dec 22, 2024 · The cursor() method in Python SQLite3 is a crucial component for executing SQL statements and managing database operations. There was a bug in the way transactions were handled, where all cursor states were reset in certain circumstances. cursor() #sample statement that works on one database cursor_db_1. Cursor. Your second cursor declaration won't work as a static cursor declaration, because the value fetched from the first cursor changes. close() May 9, 2012 · If I have multiple cursors (each in a different thread, for example) generated from the same DB connection, does a commit on one cursor (e. 27 Can I use multiple cursors on one connection with pyodbc and MS SQL Server? 2 Apr 9, 2021 · Yes, normal practice is to have one long-term database connection, using multiple cursors. execute(sqlQuery) except: cursor. I'm not sure about Python but for Node. (It wouldn't work to simply get a buffered cursor from the same connection; you'd still have to advance past the unbuffered result set before using the buffered cursor. execute(sql, args) results = cursor. Aug 24, 2015 · Are you creating a connection for each thread? If you have multiple threads you need a connection for each one (or a pool with locking mechanisms around the connections) otherwise you will have all sorts of weird issues. connect("some_db. One of the process updates the table by inserting new data and the other process retrieves informatio I have a database connection method that creates the connection and sets the cursor as a part of init process. db") c = connection. cursor() and close it with the cursor. In this article, we will explore the differences between connection. Using pyodbc my standard start is something like . Jun 14, 2020 · The second is that psycopg2 cursors are not thread-safe; a connection object can be freely used by any thread, but each cursor should be used by at most one thread. cursor() as cursor: … cursor. close() cur = con. It acts as middleware between SQLite database connection and SQL query. execute in python. 1 inserting data in database through thread Jul 27, 2021 · even in SQLite3's official documentation, which calls cursor objects "often superfluous" and provides shortcut methods which act on connections instead of cursors. Before diving into cursor operations, make sure you have a proper database connection. execute('commit') considering the fact that I am using Oracle dat Jul 26, 2022 · Exiting a function call will not close a cursor (it is possible to create a cursor in a function call, return it to the caller, and verify that the cursor is still open). execute() calls into a single transaction. cursor() #Create a cursor from the connection cur. Syntax. Cursors are created by the connection. Jan 29, 2021 · Is it possible to pass more than one query in a double with cursor opening statement with psycopg2 (first to open connection, then cursor)? E. Feb 26, 2018 · connection = sqlite3. This looks like you are hitting issue 10513, fixed in Python 2. You execute multiple SQL statements in that transaction, but you close it completely after committing. cursor) and, i am trying to query the database twice with different queries as below query1result=[] May 22, 2015 · Working with Cursors in Python. connector cnx=mysql. 2 Apr 11, 2019 · python mysqldb multiple cursors for one connection. Oct 28, 2020 · Can I use multiple cursors on one connection with pyodbc and MS SQL Server? 2 How to include multiple cursor. I am using psycopg2 module and trying to mock the cursor. x" to "1", "2", etc. That said, depending on the bottleneck, you MIGHT not see any improvement from going with multiple connections either. python mysqldb multiple cursors for one connection. 1. cursor(name='name_of_cursor') as cursor: cursor. Js libraries do not allow multiple statement executions. MySQL is thread-safe, You can let two threads share the same connection, Multiple threads cannot send a query to the MySQL server at the same time on the same connection, so each connection will be able to access their respective cursors, queries and result sets without having an effect on the other connections but each thread or process will need its own May 22, 2022 · I am connecting to Snowflake and using below query I can fetch the data for one table. Related questions. Recall that a connection object has autocommit=FALSE by default, so the cursor actually batches cursor. cursors. execute() should invoke Apr 24, 2015 · According to the documentation of cx_Oracle, the cursor should be garbage-collected automatically, and there should be no risk of a leak. Each cursor allows you to execute SQL queries independently and retrieve results. 0. Such abstraction is Jan 5, 2022 · Multiple SQL statements in a single string is often referred to as an "anonymous code block". cursor() cur. Django’s connection represents the link to your database, and with cursor. Sep 16, 2017 · Which one is more efficient than others in Python. cursor() querying: curs. results only contains the first one. db") c2 = connection2. cur. A PostgreSQL connection can handle only one statement at a given time (unless you are using a server side cursor, but even then the connection can handle only one FETCH at the same time). " So yes, you can use SQLite with multiple threads as long as your code ensures that only one thread can write to the database at any May 4, 2019 · Should I reuse the cursor object or create a new one for each query? Reusing the cursor: # we're going to connect to s3 and mysql db = mysql_connect(host="localhost", We are creating a cursor using connection. When you go beyond Django’s ORM and write raw SQL, connections and cursors make it all happen. pyodbc Cursor Reuse. connect() must return an instance of <module>. Working with Cursors in Python. Nov 6, 2014 · how could I create one database connection and use it across all the functions? I'm connecting to my database in a test file like so: con = mdb. db import connection c=connection. Mar 5, 2019 · I think about multihreading or multiprocessing in Python. Oct 7, 2012 · from psycopg2. However, dataframe only printed the result for last query. If you are using more than one database you can use django. cursor(buffered=True) cursor2 = db. execute('SELECT ') for row in cur. Return connection. It works, but I am not sure if it has any side effect. In this way, you can forget about connection and do what you something on a database. 7. db import connections Mar 16, 2022 · i've got a python 3. SQL_USER, passwd=c. xval, a. itersize = 20000 query = "SELECT * FROM Mar 9, 2021 · Create a database Connection from Python. connect(dbname= 'dbname', host='host', port= 'port', user= 'user', password= 'pwd') cur = con. do_this_with_connection() DB(). My requirement is to have one connection until we close the application. Sep 29, 2011 · Added 1/28/09: I over simplified the code to make it easy to explain, but the select statements are very long and complicated, and the second one is dependent on the first meaning after the first cursor is done and looped through and the inserts are created the second select actually looks at the first inserts as part of the where clause. You first have to FETCH a result row into a record variable, then you can use that. ) Jan 24, 2018 · with connection. connect(host = db_host, db = db_db, port = db_port, user = db_user, passwd = db_password, charset='utf8') # Initiating database cursor cur = db. db. id=t2. Average Cursors Open Per Connection: As per 2021 database usage statistics, applications open an average of 3-4 cursors per database connection. commit() # does this account for both execute statements, or just the last? I’ve reviewed the following: PyMySQL execute/commit example, but with only one example having only one execute statement. execute(SQLtype2, otherToInsert) connection. from django. I'll try to explain below. OptimizedUnicode Jun 9, 2024 · This cursor will now run queries and statements on the connected MySQL database instance. close() after the while True: at the bottom will never be called, since there are no breaks in the while True: and the only way to exit the loop is with an exception, that will not be caught and will end the thread. Otherwise, cur is now holding the results of your new "inner" select instead of your "outer" one. Also, after a quick search, I find multiple references to Multiple Active Result Sets related to this issue. def requestConnection(): "Create new connection. In this comprehensive guide, we‘ll cover everything you need to […] Mar 5, 2019 · You don't have to create a new connection each time unless you're accessing multiple databases. connector - reusing a single database connection across multiple cursors Regarding option 2. Sep 12, 2012 · Your example opens up one connection, then executes one transaction on it. pxval>0 and t2. – By your definition, a 'connection' would/could manage multiple cursors. connections is a dictionary-like object that allows you to retrieve a specific connection using its alias: from django. A cursor is needed to execute SQL using a connection and to Jan 22, 2021 · Consider encapsulating your methods inside a class object which opens connection once and re-uses cursor multiple times and on deletion of object closes the cursor and connection. connect(connectioninfohere) # create a cursor, execute and SQL statement and get the result as a tuple cursor = vDatabase. executemany(sql, seq_of_parameters) Parameters Python / mysql. Below is an example of how to use multiple cursors in Python to interact with MySQL: In Python's mysql-connector library (often used for connecting to MySQL databases), you can create and use multiple cursors for a single database connection. execute("SELECT * FROM table_name;") #Run the select you want to loop/cursor over for row in cur: #do something with every single row here #optionally Nov 13, 2016 · Now, back to our regular programming. django. It knows how to keep everything straight. If your database supports it, try adding Mar 15, 2015 · I have been using python with RDBMS' (MySQL and PostgreSQL), and I have noticed that I really do not understand how to use a cursor. execute(F'select * from {schema_1}. Jan 10, 2021 · Whenever someone connects to PostgreSQL using psycopg2 python driver, they create a connection object followed by a cursor object. extras import LoggingConnection,LoggingCursor,RealDictCursor class MixinLoggedDictCursor(LoggingCursor, RealDictCursor): pass conn = psycopg2. Aug 13, 2012 · When you have one connection object, can you make multiple cursors to that one single connection and execute queries with these cursors at the same time? Or would each cursor wait for the previous cursor to finish its query? connection type: database=MySQLdb. initialize(my_logger) Nov 29, 2023 · This just says you’ve got several cursor instances. use exactly one executescript within the with block and nothing else, or; avoid executescript entirely; you can call execute as many times as you want, subject to the one-statement-per-execute limitation. However: A cursor in MySQL (and other RDMS) is not a the user-accessible mechanism for performing operations. This may work anyway, depending on your database library and your luck, but you shouldn't count on it. connect("another_db. Allows Python code to execute PostgreSQL command in a database session. 31. execute("SELECT VERSION()") ver = cur. Refer Python SQLite connection, Python MySQL connection, Python PostgreSQL connection. connection ¶ Read-Only attribute which returns the reference to the connection object on which the cursor was created. Dec 11, 2013 · Like all Python DB-API 2. SSCursor) # put the cursorclass here cursor = connection. You get a new one every time you make one. You don't need new cursors each time. 0 implementations, the cursor. id as pid,pxval,pyval from <tbl1> t1 left join ( select * from <tbl2> where clubid="+clubid+") t2 on t1. Indeed, executemany() just runs many individual INSERT statements. with psycopg2. For example, you could end all statements with "/**/;" or TAB; Yes you would have to alter existing scripts to follow this convention and make sure to avoid this pattern elsewhere, but for me often times the sql is actually output from other sql so following this Nov 15, 2019 · I am writing unit test case for a function which has multiple sql queries in it. cursor() The cursor can be closed immediately after fetchall(). Thanks in advance! Python Code: Oct 22, 2017 · Each thread should use a distinct connection to avoid problems with inconsistent states and to make debugging easier. copy() convt[3] = int convt conn = db. cursor() Feb 12, 2019 · The __init__ method reads database configurations from an INI file in order to call the connection and set two dictionaries, one for connections and one for cursors. e. execute(), you’re sending SQL directly to your DB server, primed for high-speed processing. connect(user,password,host,database) cursor=(cnx. In particular, a connection does not need to provide means to execute SQL directly. close() When working with Python and MySQL, it is important to properly manage the connection to the database. args[0],e. commit() Psycopg's cursor class seems to have little to do with the cursors, as defined by postgres. connection_hostname = pyodbc. This works fine in SSMS: DECLARE @hi VARCHAR(10) = 'hi' SELECT @hi. cursor() You can have them running at the same time too. That cursor object is recognized as a client cursor by PostgreSQL Feb 4, 2013 · Using raw cursors with multiple databases. distance is null order by projectid) as b WHERE a Oct 2, 2021 · I want to know that performance wise which is a better option i. So: Apr 2, 2013 · In general there's no problem at all with opening and closing multiple cursors sequentially. execute('command_hostname') May 18, 2022 · TL;DR. Jan 29, 2021 · cursor_db_1 = connect_db_1. print "Error %d: %s" % (e. conversions. connections to obtain the connection (and cursor) for a specific database. commit() or cursor. Feb 9, 2010 · The cursor class¶ class cursor ¶. table. cursor() command_hostname = 'select * from everything_forever;' cursor_hostname. execute(qry1). However, my stored procedure returns two cursors. 5. fetchall() : # Initiating new instance I create a connection and a cursor like this: connection = MySQLdb. Having a cursor for each mouse means you can quickly interact with individual applications because cursors can be localized or dedicated to one program - the restriction of moving one cursor all over the screen and refocusing on a specific application is lifted. cursor() try: c. close() vs. cursor() must return an instance of <module>. 4. Recap: I need to update every record in a spatial database in which I have a data set of points that overlay dat. fetchall() for row2 in rows2: print row2 Dec 27, 2023 · As a Python developer, few skills are as important as being able to work with databases effectively. connect() cursor: curs=database. import psycopg2 def my_function(): # all connection related code goes here In an sqlite3 connection, cursor objects acts as an intermediary between the connected SQLite database and Python code. My problem is, that my old code always created a new database connection and cursor, which decreased the speed immensivl Jan 16, 2017 · This can easily mess up the transactional with connection block, so your choice is to either. 0. fetchall() cursor. Mastering its use will enable you to leverage the full potential of Python for data-driven applications. The main reason for the existence in SQLite3 of both connection and cursor objects seems to be compliance with the Python database API specification v2. connect(your_dsn) Nov 6, 2024 · Separate Work Environments: Cursors enable multiple active environments through which you can perform various database operations without interference. If you're just accessing different tables in one database then just creating a connection once is fine. Dec 10, 2019 · The Python and Node. What about have un-closed cursors, what is the effect? Jan 7, 2014 · You have to create a new cursor. Apr 30, 2014 · cur = connection. fetchall() for row in rows: qry2 = "Select * FROM Table2" rows2 = cursor. Aug 6, 2021 · I am using pymysql to connect to sql like this: con=pymysql. So if several threads were to share a database connection, they'd have to coordinate carefully to make sure that only one thread uses the connection at the Jan 13, 2015 · MAIN SCRIPT ----- #Connecting to DB db = MySQLdb. fetchall() to process the results of my stored procedure. cursor() try: cursor. executemany() function. It really doesn't seem to allow me to perform multiple executes on the same cursor. Feb 1, 2012 · A connection represents your program's connection (d'oh!) to the database software. close() return None result = cursor. 0 is specified, does not clearly define what exactly a connection or cursor is, nor what the close() method on each must do; only that <module>. connect(host='otherhost', etc) And then one creates a cursor: cursor = connection. close() or do I have to close the cursor first and then the connection? Like Aug 6, 2022 · python mysqldb multiple cursors for one connection. Execute runs a single SQL query, that is used for SQL operations like INSERT, UPDATE, or DELETE. I have two classes one is to make and get connection/cursor and using which I am able to get and fetch the data in my Service. Jul 15, 2015 · I am trying write two processes using python that require access to same sqlite database table. connect( host=host, port=port, user=username, passwd=password, db=database, cursorclass=MySQLdb. Or, if you're okay with killing what is currently executing, try cursor. Having a cursor-per-thread allows for multithreaded applications to access the DB from any thread, while sharing the same connection. Record macro's and play them back to automate tasks, even in a multi cursor scenario. Here you need to know the table and its column details. . On web servers, this is typically achieved by using a pooled connection. close() return result The cursor must be opened and already positioned on a row by means of FETCH statement. An Oracle cursor has a lifetime of the user's session and when you close the connection then you will close the session and all its related resources including cursors. The scenario should looks something like this: Create connection to the database; Create cx_Oracle. This is not an issue with Python but with MySQL. do_that_with_connection() When DB instance is __init__iated, a connection is automatically established and it is (also automatically) closeed when __del__eted. connector - reusing a single database connection across multiple cursors Hot Network Questions How to change the numeration of sections from "0. Get resultSet (all rows) from the cursor object using a cursor. 17. cursor(db. Jan 18, 2012 · I make multiple queries to my DB from my python code that uses pyodbc to connect to a SQL Server. close() function. connect('10. close() in Python’s MySQLdb […] Dec 21, 2018 · You can use commit after you executed DML (Data Manipulation Language) commands. cursor executing a bunch of deletes then closing the cursor. You can think of the cursor as basically a pointer to a query result set (and it is a set of pointers to cached data). execute('delete from table_a') c. Python MySQLdb: connection. futures to query on a DB. Cursor Object. " convt = cv. cursor() Yeah I think its fine, until you need multiple databases where all you need to do is name you connection and cursors something different like connection2 = sqlite3. If I modularize my script, creating a connection in the main module and some worker functions (no threading, just for modularization) should I Nov 11, 2024 · Connections and Cursors: The Backbone of Direct SQL Execution. I need to fetch data from 2 tables into 2 different dataframe. So I tried cursor. connect(OUTPUTDATABASE) # <-- originally :: Is this the core problem? curs = conn. cursors connection = MySQLdb. description ¶ This read-only attribute is a sequence of 11-item sequences Each of these sequences contains information describing one result column Jun 8, 2015 · Similar to another post I made, this answers that post and creates a new question. Also using multi=True can be more convenient to complete this job, but you need to run the generator which created by execute. exceute for table2. ? Jan 21, 2020 · You cannot use a cursor name like a table. May 8, 2019 · Specifically while a database session can have multiple open cursors at any one time, it can only be executing one of them. it is purely a preference on how you would like to view your code. The connection concept only provides means to handle transactions (commit and rollback) and to create cursors. It is created after giving connection to SQLite database. pid,pxval,b. connect() cursor = connection. But I believe they’ll be using the same connection and that they are serialised, so only one cursor is active at a time. connect(host=c. cancel() before reusing your connection. You believe this would be the preferred/performant way to access a database as 'connections' are expensive, and 'cursors' are cheap. Python DB API's "cursor" is simply a Jan 2, 2024 · A Python-OracleBD cursor variable is used to pass data into a bind parameter. cursor() You can also use buffered=True as connection argument to make all cursor buffering instantiated by this connection buffering. connector. cursor() # process When the MySQL-processing is done one should close the connection. Since you fetchall from each cursor you can just re-use it. cursor() Well I am using flask web framework for some use. I need a way to loop through as many cursors as I want. SQL_PASSWD, db=c. Connection. 8 script that uses the libraries pyobdc and concurrent. a) However, if I need to select something from one database, then put it into the other with one statement, I have no clue how to do that, since it required both cursors to be used Mar 25, 2014 · When a database is accessed by multiple connections, and one of the processes modifies the database, the SQLite database is locked until that transaction is committed. You have to clean/close the cursor after calling stored procecude in order to execute further sql code. yval,b. cursor. Each connection can have a query in progress, so multiple connections can execute multiple conccurent queries. One option which avoids issues with stray semicolons (whether in comments or expressions) is to split on multiple characters. Jan 1, 2012 · Indicates if the cursor is closed and can’t be reused. Opening a cursor allocates a pointer and closing one frees the memory. sxokp zdstyq fshppj wzyxb vwxbz qzpim mxc ifh xjlnug jvimbn mkzq viddct xnxvi kugo akbroc