Tutorial by Examples: p

There are hundreds of settings that can be placed in my.cnf. For the 'lite' user of MySQL, they won't matter as much. Once your database becomes non-trivial, it is advisable to set the following parameters: innodb_buffer_pool_size This should be set to about 70% of available RAM (if you have a...

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PrimitiveBoxed TypeMemory Size of primitive / boxedbooleanBoolean1 byte / 16 bytesbyteByte1 byte / 16 bytesshortShort2 bytes / 16 bytescharChar2 bytes / 16 bytesintInteger4 bytes / 16 byteslongLong8 bytes / 16 bytesfloatFloat4 bytes / 16 bytesdoubleDouble8 bytes / 16 bytes Boxed objects always requ...

You update all rows in table by simply providing a column_name = value: UPDATE person SET planet = 'Earth';

UPDATE person SET state = 'NY' WHERE city = 'New York';

You can update multiple columns in a table in the same statement, separating col=val pairs with commas: UPDATE person SET country = 'USA', state = 'NY' WHERE city = 'New York';

You can also update data in a table based on data from another table: UPDATE person SET state_code = cities.state_code FROM cities WHERE cities.city = city; Here we are joining the person city column to the cities city column in order to get the city's state code. This is then used to updat...

Despite String is a reference type == operator compares string values rather than references. As you may know string is just an array of characters. But if you think that strings equality check and comparison is made character by character, you are mistaken. This operation is culture specific (see ...

Say we are working on a class representing a Person by their first and last names. We have created a basic class to do this and implemented proper equals and hashCode methods. public class Person { private final String lastName; //invariant - nonnull private final String firstName; //in...

The Comparable<T> interface requires one method: public interface Comparable<T> { public int compareTo(T other); } And the Comparator<T> interface requires one method: public interface Comparator<T> { public int compare(T t1, T t2); } These two met...

Environments in R can be explicitly call and named. Variables can be explicitly assigned and call to or from those environments. A commonly created environment is one which encloses package:base or a subenvironment within package:base. e1 <- new.env(parent = baseenv()) e2 <- new.env(parent ...

Functions and objects in different packages may have the same name. The package loaded later will 'mask' the earlier package and a warning message will be printed. When calling the function by name, the function from the most recently loaded package will be run. The earlier function can be accessed ...

Microsoft.CodeAnalysis.CSharp.Scripting.CSharpScript is a new C# script engine. var code = "(1 + 2).ToString()"; var run = await CSharpScript.RunAsync(code, ScriptOptions.Default); var result = (string)run.ReturnValue; Console.WriteLine(result); //output 3 You can compile and run an...

Microsoft.CSharp.CSharpCodeProvider can be used to compile C# classes. var code = @" public class Abc { public string Get() { return ""abc""; } } "; var options = new CompilerParameters(); options.GenerateExecutable = false; options.GenerateInMe...

A package is made up of multiple Python files (or modules), and can even include libraries written in C or C++. Instead of being a single file, it is an entire folder structure which might look like this: Folder package __init__.py dog.py hi.py __init__.py from package.dog import woof fro...

This example shows how Stopwatch can be used to benchmark a block of code. using System; using System.Diagnostics; public class Benchmark : IDisposable { private Stopwatch sw; public Benchmark() { sw = Stopwatch.StartNew(); } public voi...

The following command imports CSV files into a MySQL table with the same columns while respecting CSV quoting and escaping rules. load data infile '/tmp/file.csv' into table my_table fields terminated by ',' optionally enclosed by '"' escaped by '"' lines terminated by '\n' ignore 1...

Installing the haystack package pip install django-haystack Configuration Add haystack to your project's INSTALLED_APPS inside of your settings.py file: # settings.py INSTALLED_APPS = [ 'django.contrib.admin', 'django.contrib.auth', 'django.contrib.contenttypes', # Put...

Create custom class for calling multipart/form-data HttpURLConnection request MultipartUtility.java public class MultipartUtility { private final String boundary; private static final String LINE_FEED = "\r\n"; private HttpURLConnection httpConn; priva...

HTTP/1.0 was described in RFC 1945. HTTP/1.0 does not have some features that are today de-facto required on the Web, such as the Host header for virtual hosts. However, HTTP clients and servers sometimes still declare they use HTTP/1.0 if they have incomplete implementation of the HTTP/1.1 protoc...