python database access here is simple example showing how some of these operations are used with the sqlite database modulewhich is built-in libraryimport sqlite conn sqlite connect("dbfile"cur conn cursor(example of simple query cur execute("select namesharesprice from portfolio where account= "looping over the results while truerow cur fetchone(if not rowbreak process the row namesharesprice row an alternative approach (using iterationcur execute("select namesharesprice from portfolio where account= "for namesharesprice in curprocess the row forming queries critical part of using the database api involves forming sql query strings to pass into the execute*(methods of cursor objects part of the problem here is that you need to fill in parts of the query string with parameters supplied by the user for exampleyou might be inclined to write code like thissymbol "aigaccount cur execute("select shares from portfolio where name='%sand account=% (symbolaccount)although this "works,you should never manually form queries using python string operations like this if you doit opens up your code to potential sql injection attack-- vulnerability that someone can use to execute arbitrary statements on the database server for examplein the previous codesomeone might supply value for symbol that looks like "evil laugh'drop table portfolio;--which probably does something other than what you anticipated all database modules provide their own mechanism for value substitution for exampleinstead of forming the entire query as shownyou might do this insteadsymbol "aigaccount cur execute("select shares from portfolio where name=and account=?"(symbolaccount)herethe '?placeholders are successively replaced with values from the tuple (symbolaccountsadlythere is no standard convention for placeholders across database module implementations howevereach module defines variable paramstyle that indicates the formatting of value substitutions to be used in queries possible values of this variable are as followsf lib fl ff