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However, if a. Local variables - variables declared in an inner block and not accessible to outer blocks. Following exam pl e shows the usage of Local and Global variables in its sim pl e form:.

INTO list. The following exam pl e illustrates the concept: Let us create a table named. It requires an initial value and does not. A literal is an ex pl icit numeric, character, string, or Boolean value not represented by an. The following table provides exam pl es from all these categories of literal values.

To embed single quotes within a string literal, pl ace two single quotes next to each other as. This tutorial will ex pl ain the arithmetic, relational, comparison and logical operators one by one.

Relational operators compare two expressions or values and return a Boolean result. Assume variable A holds 10 and. Comparison operators are used for comparing one expression to another.

The result is always. All these operators work on. Certain operators have higher precedence than others; for exam pl e, the. Here, operators with the highest precedence appear at the top of the table, those with the lowest. Within an expression, higher precedence operators will be evaluated first.

Following is the general from of a typical conditional i. It is the sim pl est form of IF control statement, frequently used in decision making and changing. If the condition is TRUE, the statements get executed, and if the. Where condition is a Boolean or relational condition and S is a sim pl e or compound statement. Let us try a com pl ete exam pl e that would illustrate the concept:. ELSE statement. However, to select the sequence, the CASE statement uses a selector rather than multi pl e.

Boolean expressions. A selector is an expression, whose value is used to select one of several. In general, statements are executed sequentially: The first statement in a function is. Programming languages provide various control structures that allow for more com pl icated. A loop statement allows us to execute a statement or group of statements multi pl e times and.

The initial step is executed first, and only once. This step allows you to declare and initialize. Next, the condition ,i. If it is TRUE, the body of the. After the body of the for loop executes, the value of the counter variable is increased or. By default, iteration proceeds from the initial value to the final value, generally upward from the. However, you must write the range bounds in ascending not descending order. The following. Following section shows few exam pl es to.

The label name can also appear at the. You may use the label in the EXIT statement to exit from the loop. Labeling loops also helps in taking the control. If you are using nested loops i. In other words, it forces the next iteration of the loop to. Any program that uses a GOTO can be rewritten so that it doesn't need the. Variable-length strings: In such strings, a maximum length up to 32,, for the string is.

A string literal is enclosed within quotation. To include a single quote inside a string literal, you need to type two single quotes next to one. If you need to declare a variable-length string, you must provide the maximum length of that. The following exam pl e illustrates declaring and. The following table provides. Pads x with spaces to left, to bring the total length of the string up to width characters. Returns a substring of x that begins at the position specified by start. An optional length.

The following exam pl es illustrate some of the above-mentioned functions and their use:. A varray is used to store an. All varrays consist of contiguous memory locations. The lowest address corresponds to the first. An array is a part of collection type data and it stands for variable-size arrays. We will study. Each element in a varray has an index associated with it. It also has a maximum size that can be. Following exam pl e makes use of cursor, which you will study in detail in a separate chapter.

This is basically called the 'Modular design'. A subprogram created inside a package is a packaged subprogram. It is stored in the database. It is an optional part. However, the declarative part for a subprogram does not start with the.

The following exam pl e creates a sim pl e procedure that dis pl ays the string 'Hello World! An IN parameter lets you pass a value to the subprogram.

It is a read-only parameter. It cannot be assigned a value. You can. You can also. It is. You can change its value and reference the value after assigning. This procedure computes the square of value of a passed value. This exam pl e shows how we. In positional notation, the first actual parameter is substituted for the first formal parameter; the.

So, a is. In named notation, the actual parameter is associated with the formal parameter using the arrow. In mixed notation, you can mix both notations in procedure call; however, the positional notation.

The sim pl ified. The following exam pl e illustrates creating and calling a standalone function. This function returns. While creating a function, you give a definition of what the function has to do.

To use a function,. When a program calls a function,. A called function performs defined task and when its return statement is executed or when it last.

To call a function you sim pl y need to pass the required parameters along with function name and. The following is one more exam pl e which demonstrates Declaring, Defining, and Invoking a. To illustrate the concept, let us calculate the factorial of a number.

Factorial of a number n is. The following program calculates the factorial of a given number by calling itself recursively:. A cursor is a pointer to this context area. The set of rows the cursor. You can name a cursor so that it could be referred to in a program to fetch and process the rows.

Im pl icit cursors are automatically created by Oracle whenever an SQL statement is executed,. Programmers cannot control the im pl icit. The following program would update the table and increase salary of each customer by and.

If you check the records in customers table, you will find that the rows have been updated:. Ex pl icit cursors are programmer defined cursors for gaining more control over the context area. It is created. Opening the cursor allocates memory for the cursor and makes it ready for fetching the rows.

For exam pl e, we will open above-defined cursor as. Fetching the cursor involves accessing one row at a time. For exam pl e we will fetch rows from. Closing the cursor means releasing the allocated memory. For exam pl e, we will close aboveopened. Following is a com pl ete exam pl e to illustrate the concepts of ex pl icit cursors:.

For exam pl e, you want to keep track of your books in a library. You might want to track the. A record containing a. The following exam pl e would illustrate the concept of table-based records. We will be using the. The following exam pl e would illustrate the concept of cursor-based records. We will be using. Records consist of different fields. Suppose you want to keep track of your books in a library. To access any field of a record, we use the dot.

The member access operator is. You would access the record fields in the similar way as you have accessed in the. There are two types of exceptions:. The General Syntax for exception handling is as follows. Here, you can list down as many as. Let us write some sim pl e code to illustrate the concept. The above program dis pl ays the name and address of a customer whose ID is given. You can use above syntax in raising Oracle standard exception or any user-defined exception.

Next section will give you an exam pl e on raising user-defined exception, similar way you can. The following exam pl e illustrates the concept. This program asks for a customer ID, when the. Triggers are, in fact, written to be executed in response to any of the following. WHEN condition : This provides a condition for rows for which the trigger would fire. The following program creates a row level trigger for the customers table that would fire for.

Because this is a new record so old salary is not available and above result is coming as null. All objects pl aced in the specification are called public objects. Any subprogram not in the. The following code snippet shows a package specification having a single procedure.

The package body has the codes for various methods declared in the package specification and. The following program provides a more com pl ete package. When the above code is executed at SQL prompt, it creates the above package and dis pl ays the. Above exam pl e makes use of nested table which we will discuss in the next chapter. When the. In this chapter, we will discuss. However, these two types of tables. An index-by table also called an associative array is a set of key-value pairs. Each key is.

The key can be either an integer or a. An index-by table is created using the following syntax. Here, we are creating an index-by table.

Following exam pl e shows how to create a table to store integer values along with names and. We will use the. A nested table is like a one-dimensional array with an arbitrary number of elements.

However, a. An array is always dense, i. A nested array is dense. A nested table can be stored in a database column and so it could be used for sim pl ifying SQL. An associative array cannot. It is called atomic because the database modifications brought about by.

A transaction has a beginning and an end. A transaction starts when one of the following events. When a transaction is aborted due to some unprecedented situation, like system failure, the. Savepoints are sort of markers that help in s pl itting a long transaction into smaller units by. By setting savepoints within a long transaction, you can roll back to a.

Both datetime and interval data types consist of fields. The values of these fields determine the. The following table lists the fields and their possible values for datetimes. It is specified. The time zone offset is the difference in hours. Let us look at a small code snippet that would dis pl ay all the user tables in the database.

Try it in. Objects have attributes and methods. Attributes are properties of an object and are used for. Below is an exam pl e. Let's create one more object customer where we will wrap attributes and methods together to. Defining an object type provides a blueprint for the object.

To use this object, you need to create. You can access the attributes and methods of the object using the. The object body defines the. Constructors are functions that return a new object as its value. Every object has a system. Map method: The Map method is a function im pl emented in such a way that its value. For exam pl e, for a customer object, if the. Order method: The Order methods im pl ement some internal logic for comparing two.

For exam pl e, for a rectangle object, a rectangle is bigger than another rectangle if. To im pl ement inheritance, the base. Let us create another object. The Loop Control Statements Loop co. Hello World Hello World Executing a Standalone Procedure A. Example: The following example illu. The following program calculates th. The syntax for declaring an excepti.

Creating Triggers The syntax for cr. Salary difference: Because this is. Package Body The package body has t. Checks the Maximum Size of a Collec.

Using Map method Let us try to unde. When the above code is executed at. Any content from tutorial spoint. This tutorial may contain inaccuracies or errors and tutorial spoint provides no guarantee regarding the accuracy of the site or its contents including this tutorial.

Prerequisites Before proceeding with this tutorial , you should have a basic understanding of software basic concepts like what is database, source code, text editor and execution of programs, etc. If you already have understanding on SQL and other computer programming language, then it will be an added advantage to proceed.

Direct call can also be made from external programming language calls to database. It offers extensive error checking. It offers numerous data types. It offers a variety of programming structures. It supports structured programming through functions and procedures. It supports object-oriented programming. This reduces network traffic and provides high performance for the ap pl ications.

These commands are then sent to the database for processing. Once the statements are processed, the results are sent back and dis pl ayed on screen. You can download a trial version of Oracle 11g from the following link: Download Oracle 11g Express Edition You will have to download either 32bit or 64 bit version of the installation as per your operating system. You will also use similar steps on your operating system, does not matter if it is Linux or Solaris.

Just modify Oracle Base and rest of the locations will set automatically. Second, you will have to provide a password, which will be used by system DBA. Step 8 Just wait, until Oracle starts doing required configuration. Just click OK button and come out. So a better option is to use command files. Save the file with the. Finally, just press enter to execute the code, if it is not already executed. Each block consists of three sub-parts: S. It is an optional section and defines all variables, cursors, subprograms, and other elements to be used in the program.

It should have at least one executable line of code, which may be just a NULL command to indicate that nothing should be executed. This section is again optional and contains exception s that handle errors in the program. The identifiers consist of a letter optionally followed by more letters, numerals, dollar signs, underscores, and number signs and should not exceed 30 characters. By default, identifiers are not case-sensitive. You cannot use a reserved keyword as an identifier.

All programming languages allow for some form of comments. Point ers to large objects that are stored separately from other data items, such as text, graphic images, video clips, and sound waveforms.

Data items that have internal components that can be accessed individually. For exam pl e, collections and records.

Point ers to other data items. Alphanumeric values that represent single characters or strings of characters. Logical values on which logical operations are performed. Dates and times.

ANSI specific fixed-point type with maximum precision of 38 decimal digits. IBM specific fixed-point type with maximum precision of 38 decimal digits. For exam pl e, the default might be 'DD-MON-YY', which includes a two-digit number for the day of the month, an abbreviation of the month name, and the last two digits of the year, for exam pl e, OCT Each DATE includes the century, year, month, day, hour, minute, and second.

Used to store large binary objects in the database. Used to store large blocks of character data in the database. Cannot exceed 4 gigabytes GB. A subtype has the same valid operations as its base type, but only a subset of its valid values. A null can be assigned but it cannot be equated with anything, including itself.

By default, variable names are not case-sensitive. For this chapter, let us study only basic variable types. It is a good programming practice to initialize variables properly otherwise, sometimes program would produce unexpected result. There are two types of variable scope: Local variables - variables declared in an inner block and not accessible to outer blocks.

Global variables - variables declared in the outermost block or a package. A constant declaration specifies its name, data type, and value, and allocates storage for it. It requires an initial value and does not allow that value to be changed. Relational Operators Relational operators compare two expressions or values and return a Boolean result. All these operators work on Boolean operands and produces Boolean results. If both the operands are true then condition becomes true.

Called logical OR Operator. If any of the two operands is true then condition becomes true. Called logical NOT Operator. Used to reverse the logical state of its operand. If a condition is true then Logical NOT operator will make it false. A and B is false. A or B is true. This affects how an expression is evaluated.

Here, operators with the highest precedence appear at the top of the table, those with the lowest appear at the bottom. Click the following links to check their detail. If the condition is true, the statements get executed and if the condition is false or NULL then the IF statement does nothing.

If the condition is false or NULL , then only the alternative sequence of statements get executed. It ensures that either of the sequence of statements is executed. It allows you to choose between several alternatives. However, to select the sequence, the CASE statement uses a selector rather than multi pl e Boolean expressions. A selector is an expression whose value is used to select one of several alternatives. IF - THEN statement It is the sim pl est form of IF control statement, frequently used in decision making and changing the control flow of the program execution.

A selector is an expression, whose value is used to select one of several alternatives. In general, statements are executed sequentially: The first statement in a function is executed first, followed by the second, and so on. Programming languages provide various control structures that allow for more com pl icated execution paths. At each iteration, the sequence of statements is executed and then control resumes at the top of the loop.

Repeats a statement or group of statements until a given condition is true. It tests the condition before executing the loop body. Execute a sequence of statements multi pl e times and abbreviates the code that manages the loop variable. You can use one or more loop inside any another basic loop, while or for loop. With each iteration, the sequence of statements is executed and then control resumes at the top of the loop.

This step allows you to declare and initialize any loop control variables. If it is TRUE, the body of the loop is executed. If it is FALSE, the body of the loop does not execute and flow of control jumps to the next statement just after the for loop.

After the body of the for loop executes, the value of the counter variable is increased or decreased. The condition is now evaluated again. If it is TRUE, the loop executes and the process repeats itself body of loop, then increment step, and then again condition. In such case, iteration proceeds the other way. After each iteration, the loop counter is decremented.

SQL Data Types. SQL — Operators. SQL — Expressions. SQL Group By. SQL Distinct Keyword. SQL Constraints. SQL Using Joins. SQL Alias Syntax. SQL — Indexes. SQL Using Views. SQL Having Clause. SQL — Transactions. SQL Wildcard Operators. SQL Date Functions. SQL Temporary Tables. SQL — Clone Tables. SQL — Sub Queries.

SQL — Using Sequences. SQL — Handling Duplicates. SQL — Injection. What is SQL? SQL is Structured Query Language, which is a computer language for storing, manipulatingand retrieving data stored in a relational database. SQL 1 SQL is a language to operate databases; it includes database creation, deletion, fetching rows, modifying rows, etc.

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