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Page 2332 of 2547
How to retrieve auto-incremented value generated by PreparedStatement using JDBC?
While creating a table, in certain scenarios, we need values to column such as ID, to be generated/incremented automatically. Various databases support this feature in different ways.In MySQL database you can declare a column auto increment using the following syntax.CREATE TABLE table_name( ID INT PRIMARY KEY AUTO_INCREMENT, column_name1 data_type1, column_name2 data_type2, column_name3 data_type3, column_name4 data_type4, ............ ........... );While inserting records in a table there is no need to insert value under the auto-incremented column. These will be generated automatically.For example, in a table if we have a column with name ID and data type ...
Read MoreHow to create a table with auto-increment column in MySQL using JDBC?
While creating a table, in certain scenarios, we need values to column such as ID, to be generated/incremented automatically. Various databases support this feature in different ways.In MySQL database you can declare a column auto increment using the following syntax.CREATE TABLE table_name( ID INT PRIMARY KEY AUTO_INCREMENT, column_name1 data_type1, column_name2 data_type2, column_name3 data_type3, column_name4 data_type4, ............ ........... );MySQL query to create a table with auto-incremented column.CREATE TABLE Sales( ID INT PRIMARY KEY AUTO_INCREMENT, ProductName VARCHAR (20) NOT NULL, CustomerName VARCHAR (20) NOT NULL, DispatchDate date, DeliveryTime timestamp, Price ...
Read MoreCan we return this keyword from a method in java?
The "this" keyword in Java is used as a reference to the current object, within an instance method or a constructor. Using this you can refer the members of a class such as constructors, variables, and methods.Returning “this”Yes, you can return this in Java i.e. The following statement is valid.return this;When you return "this" from a method the current object will be returned.ExampleIn the following Java example, the class Student has two private variables name and age. From a method setValues() we are reading values from user and assigning them to these (instance) variables and returning the current object.public class Student ...
Read MoreGet Array Dimensions in Java
In order to get Array Dimensions in Java, we use the getClass(), isArray() and getComponentType() methods with decision making in combination with iterative statements.The getClass() method method returns the runtime class of an object. The getClass() method is a part of the java.lang.Object class.Declaration − The java.lang.Object.getClass() method is declared as follows −public final Class getClass()The isArray() method checks whether the passed argument is an array. It returns a boolean value, either true or falseSyntax - The isArray() method has the following syntaxArray.isArray(obj)The getComponentType() method returns the Class denoting the component type of an array. If the class is not an ...
Read MoreMeasure execution time of small Python code snippets (timeit)
The Timer class and other convenience functions in timeit module of Python's standard library are designed to provide a mechanism to measure time taken by small bits of Python code to execute. The module has a command line interface and the functions can be called from within program as well.Easiest way to measure time of execution is by using following convenience functiontimeit()This function returns object of Timer class. It mainly requires two parameters.stmt − a string containing valid Python statement whose execution time is to be measured.setup − a string containing Python statement which will be executed once, primarily to ...
Read MorePython Utilities for with-statement contexts (contextlib)
contextlib module of Python's standard library defines ContextManager class whose object properly manages the resources within a program. Python has with keyword that works with context managers. The file object (which is returned by the built-in open() function) supports ContextManager API. Hence we often find with keyword used while working with files.Following code block opens a file and writes some data in it. After the operation is over, the file is closed, failing which file descriptor is likely to leak leading to file corruption.f = open("file.txt", "w") f.write("hello world") f.close()However same file operation is done using file's context manager capability ...
Read MoreTop-level script environment in Python (__main__)
A module object is characterized by various attributes. Attribute names are prefixed and post-fixed by double underscore __. The most important attribute of module is __name__. When Python is running as a top level executable code, i.e. when read from standard input, a script, or from an interactive prompt the __name__ attribute is set to '__main__'.>>> __name__ '__main__'From within a script also, we find a value of __name__ attribute is set to '__main__'. Execute the following script.'module docstring' print ('name of module:', __name__)Outputname of module: __main__However, for an imported module this attribute is set to name of the Python script. ...
Read MoreBuilt-in objects in Python (builtins)
The builtins module is automatically loaded every time Python interpreter starts, either as a top level execution environment or as interactive session. The Object class, which happens to be the base class for all Python objects, is defined in this module. All built-in data type classes such as numbers, string, list etc are defined in this module. The BaseException class, as well as all built-in exceptions, are also defined in it. Further, all built-in functions are also defined in the built-ins module.Since this module is imported in the current session automatically, normally it is not imported explicitly. All the built-in ...
Read MoreAccessing The Unix/Linux password database (pwd)
The pwd module in standard library of Python provides access to the password database of user accounts in a Unix/Linux operating system. Entries in this Password database are atored as a tuple-like object. The structure of tuple is according to following passwd structure pwd.h file in CPython APIIndexAttributeMeaning0pw_nameLogin name1pw_passwdOptional encrypted password2pw_uidNumerical user ID3pw_gidNumerical group ID4pw_gecosUser name or comment field5pw_dirUser home directory6pw_shellUser command interpreterThe pwd module defines the following functions −>>> import pwd >>> dir(pwd) ['__doc__', '__loader__', '__name__', '__package__', '__spec__', 'getpwall', 'getpwnam', 'getpwuid', 'struct_passwd']getpwnam() − This function returns record in the password database corresponding to the specified user name>>> pwd.getpwnam('root') pwd.struct_passwd(pw_name ...
Read MorePage Rank Algorithm and Implementation using Python
The PageRank algorithm is applicable in web pages. Web page is a directed graph, we know that the two components of Directed graphsare -nodes and connections. The pages are nodes and hyperlinks are the connections, the connection between two nodes.We can find out the importance of each page by the PageRank and it is accurate. The value of the PageRank is the probability will be between 0 and 1.The PageRank value of individual node in a graph depends on the PageRank value of all the nodes which connect to it and those nodes are cyclically connected to the nodes whose ...
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