The JVM translates Java bytecode into code that can be understood by the platform on which the code is running. The bytecode that the JVM translates is typically generated from programs written in Java, although other programming languages can also be used to generate the Java bytecode for the JVM. The JVM executes compiled .class or .jar files.

When a JRE instance is created it runs as the JVM so these initialisms can be used interchangably.

For example, take the following JSON packet:

{“results”:1,”rows”:[{"PaintingName":"Fran"}]}

This JSON can be read as follows:

var paintingJSON = Ext.util.JSON.decode(responseObject.responseText.trim());
var paintingName = paintingJSON.rows[0].PaintingName;
console.log(paintingName);

• Go to http://www.java.com/en/download/manual.jsp
• Click on the link that is relevant to your computer setup (Windows, Linux, etc.)
• A popup dialog will appear. Click “Save File”
• The file will download to your computer. When it has completely download, open it.
• Click “Run” and follow the instructions.
• To verify that the install was successful, open a command prompt and type “java -version” or

For example, instead of:

alert(myVar);

Use:

console.log(myVar);

console.log is especially useful if you need to output a series of variables, such as in a loop. With console.log, all the variables are output at once, whereas with alert, you have to click the pesky “OK” button for each variable that is output.

In Windows XP: Control Panel – System – Advanced Tab – Click on the “Environment Variables” Button
In Windows Vista/7: Control Panel – System and Maintenance – Advanced System Settings – Click on the “Environment Variables” button

Once the dialog has been accessed, in the “System Variables” section, specify a variable name and value. Typical values are listed below:

Variable name: JAVA_HOME
Variable value: c:\Program Files\java\jdk1.6.0_17  (Where Java is installed on your computer)

java -version

A constraint is typically defined as part of the table definition as is created using something similar to the following syntax:

CREATE TABLE ORDERS (
ORDER_ID NUMBER(7) NOT NULL,
PRODUCT_ID NUMBER(7) NOT NULL,
PRODUCT_NAME VARCHAR2(100) NOT NULL,
CONSTRAINT ORDER_ID_PK
PRIMARY KEY(ORDER_ID),
CONSTRAINT PRODUCTS_PRODUCT_ID_FK
FOREIGN KEY(PRODUCT_ID)
REFERENCES PRODUCTS(PRODUCT_ID)
)
The preceding table definition creates two constraints: one for the primary key on the ORDER_ID column; and one for the PRODUCT_ID column foreign key.

Constraints can also be created on a table using the ALTER TABLE syntax, as follows:

ALTER TABLE ORDERS
ADD CONSTRAINT PRODUCTS_PRODUCT_ID_FK
FOREIGN KEY(PRODUCT_ID)
REFERENCES PRODUCTS(PRODUCT_ID)

The Oracle varchar2 data type allows for the storage of up to 4000 bytes of character data. It can be defined for a column as follows:

MyColumn varchar2(100) DEFAULT ‘MyString’ NOT NULL;

Note that the varchar data type is now deprecated in Oracle as it’s usage has become a synonym for varchar2, although this may change in future versions.