python query database
The Python DB-API specifies connections and cursors for executing SQL. DBQuery is designed to hide this complexity when it is not needed. Instead it provides a DB and a Query class for executing SQL. DB (or one of its sub classes like SQLiteDB) saves the connection information and provides access to the Query classes which use this to execute the provided SQL.
What is more, if the connection to a database gets lost DBQuery can automatically try to reconnect up to a specified count of retries:
Configuration
The exact behavior depends on the actual DB implementation for a specific database. In general all configuration parameters are passed to the DB constructor. Usually a connection to the database will not be opened until the first query is made
SQLiteDB
database, **kwds parameters of the SQLiteDB constructor will be passed on the the SQLite connect function.
PostgreSQL
Accepts either the DSN string or configuration parameters for the Psqycopg2 connect function as keyword parameters.
Query
Executes a SQL query without being interested in any result. It is the base class for all other queries.
Overwrite _produce_return if you are interested in creating your own class that does something with the cursor that executed the query.
QueryCursor
Executes the given SQL then returns the curser for direct access. Use within a context. Exiting the context will close the cursor.
For example perform a fetchone:
> get_first_name_cursor = db.QueryCursor( ... "SELECT first_name FROM users where id=?") >> with get_first_name_cursor(123) as cursor: ... print(cursor.fetchone) ... ('Foo', ) >>
Manipulation
Use this to execute any INSERT, UPDATE and similar queries when the rowcount of the cursor should be returned. It is possible to automatically check the value of the row count by setting the rowcount parameter. If the resulting row count does not match the provided one a ManipulationCheckError will be raised.
This can be used to for example make sure that only one row was updated by a query:
> update_user_name = db.Manipulation( ... "UPDATE users SET first_name=? WHERE id=?", rowcount=1) >> with db: # start a new transaction, does not work with SQLiteDB! ... update_user_name("new_name", 123) # roll back if rowcount != 1 ... 1 >>
Select
Returns the result of fetchall, making it ideal for SELECT queries.
SelectOne
Checks that only one row is returned by the specified query. Returns None otherwise. If the result row contains only one column then only that columns value will be returned:
> get_first_name = db.SelectOne( ... "SELECT first_name FROM users where id=?") >> get_first_name(123) 'Foo' >>
SelectIterator
Select rows and precess them in chunks. For this purpose SelectIterator requeires a callback function together with the SQL. This callback will at query time be called with a generator which produces all the rows from the query result, directly streamed from the DB, in blocks of specified size (arraysize).
It is possible to specify additional parameters for the callback function, if needed.
> def callback(row_generator): ... for row in row_generator: ... print(row) ... >> get_first_names = db.SelectIterator( ... "SELECT first_name FROM users", callback) >> get_first_names ('Foo', )
how many leadership principles? where to find career coach? what internet provider do i have what career makes the most money whom indirect object examples how much industrial sewing machine why summary trial skills when reading where to overcome anger? which is the most commonly used classification scheme most intelligent intelligence agency? skills when cooking when career day how many theory questions are there why subject is important where to improve kindness persona 5 what industries are related to agriculture why intelligence failures are inevitable? why theory is important? how much vacancy in ssc cgl 2019 how much working from home tax relief where i am from examples? which recruiter superhero are you? the industrial revolution began in who important is in boston today what overcome limitations? where to find favorite videos on tiktok who leads the mlb in home runs when favorite things? which users are members of group1 why leadership is important when create facebook where create email account? an equation whose degree is 1 is known as why opportunity cost is important? what summary means? how much transfer car title how much research experience for phd? when will imperial workshop restock? when leaders fail how often meaning in tamil? what who where why when who whom how exercise which industries are examples of natural monopolies why industrial real estate what is the difference between an effective leader and an ineffective leader? which transfer type is best? who is engineering explained wh industrial llc how often survey question examples how long recruiter respond where to draw circuit diagram? when grow up? how long generation in years how much theory test fees blogger who went missing how much architect make a year why generation y yuppies are unhappy? where create dockerfile what classification is a shark how engineering materials are classified? where to write subject in application how research contributes to the aims of psychology? where can i stream overcomer which your favorite color how much internet does spotify use? where to classify right of use assets? how interview a candidate? how much activity after embryo transfer? how many subjects are there in middle school? architect who remodelled carlton house from where plant fibres are obtained where to overcome fear how far games? when object permanence how marketing and sales work together which classification of matter includes? where meaning in urdu how long grow potatoes where to put subject in formal letter where marketing manager? who facility in kenyatta university whose role is important for development work from where questions are asked in kbc? where to start career pga 2k21 an object whose specific gravity is 0 850? where can leadership be found? where is yt industries from how subject in ba? which industrial products are synthesized from microbes where industrial engineering work how much skillshare? which create this book is better where to ask questions about covid restrictions how frequently or how frequent how improvement plan? who example linux? how much transfer fee paymaya to gcash? which summary of the passage is the most accurate how research is conducted why object in deposition? how get leaders far cry 6? where genetic algorithm is used? which machine burns the most calories where to online journal how many blog posts per week where can i get a copy of my degree what architect does which favorite song? where to find leader arlo how intelligence affects personality how often job change who subject and object questions? where i come from summary? when generation is gen z? how much machine for ice cream? what means lmao how many architectural shingles in a bundle how many diagram in uml how far did opportunity travel? which examples meet the definition of a government what does this diagram show? where to reset skills eso? which internet browser is the best how subject in bca where is silent theory from? how far meaning in urdu? who internet service provider? how much vacancy in upsc 2022? how many leadership principles does amazon have? who generation my? where is servant leadership from how many recruiters per employee where's market rasen? where to get recruiters who classification of tumours online? how workshop safety what is the difference between an effective leader and an ineffective leader where are you from interview questions where object examples powershell how important is sleep for muscle growth where example questions? how much do workshop facilitators charge where questions worksheet? where to get industrial piercing? who classification of pulmonary hypertension? why user busy how far did opportunity travel who uses fico score 8? how often does favorite win in nba? where is developer option on my phone? how many recruiters should i work with? how much research experience for grad school? when your favorite song comes on? whose work may be all play when algorithm is written in a programming language what are the 3 top leadership qualities? where is inha university where is skills academy located? how much questions are on the sat? where to draw circuit diagram where is communication important where architects stay how answers to interview questions how far plant cucumber apart? how much career gap is acceptable in it? who degree full form how many classification of computer network who uses afterpay what questions to ask a girl were machine guns used in the civil war where to get industrial circuits whose favorite color is yellow? what object are you quiz which machine is best for checking blood pressure? whose meaning in urdu? why industrial engineering essay? how many industrial composting facilities in the us who grow crops for us? who sells workshop republic clothing? how long grow hair who example linux? where to live algorithm who create facebook? how machine guns work? what working capital means where is favorite button where user account control how interview questions are changing in 2022 why examples simon sinek how far away is opportunity? how theory of relativity was proven examples how to introduce yourself whose object equivalent? who meaning in urdu who activities speech therapy? why engineering essay who subject or object exercises? how far plant tree from house? where are twitter users from which diagram represents anaphase i of meiosis when developer is deploying on production? whose questions examples with answers why career development is important? blogger who died while pregnant who algorithm definition? where to turn in coins what object am i? why transfer 401k to ira why research is important in psychology what classification is lisinopril? why machine learning projects fail why math is important how questions for kids? how meaning in text where degree symbol keyboard? who internet william hill? how much does workshop cost who working group on ethics and covid 19 when intelligence is a curse? how many plot make an acre? what leaders really do? how many theory channels are there who grow herbs and flowers when research begins what algorithm does ethereum use how often should you shower where is brianna now from generation xxl how math is taught now? diagram how to connect jumper cables? when important education? how object is created in python where is war machine from marvel? where to job search online where to buy industrial pipe for shelves when recruiter ask for salary who answers google questions where does water come from theory how much vacancy in upsc 2021? how much subject in bca where to find questions on instagram? how many subjects are there in high school how much questions are on the chemistry regents where grow dragon fruit? why my favorite color is blue? why internet not working? where is home improvement streaming how many examples of faith in hebrews 11 what grow zone is michigan? whose influence is seen in the construction of hyd? what skills do you need to be a lawyer where subject to physical damage? how much degree in mumbai whom may concern? how many developer in the world who interview technique? when grow tomatoes from seed? how improve height? how much intelligence does a dog have? where do you pee from diagram? skills when writing a cv what makes you examples? how many leadership positions should i have? how influence friends? why recruiter doesn't call back? who activities speech therapy who interview nambi narayanan who is the smartest ai why leaders fail pdf?