<strong>Syntax for uisng NLS_LOWER Function</strong>

NLS_LOWER(  ‘string’,'nlsparam’);

Both string and 'nlsparam' can be  CHAR, VARCHAR2, NCHAR, NVARCHAR2, CLOB, or NCLOB. The output  returned is of VARCHAR2 datatype if string is a character datatype and a LOB if string is a LOB datatype.

The 'nlsparam' can have the same form and serve the same purpose as in the NLS_INITCAP function.

The following Query  returns the character string ‘New City'‘ using the XFrench linguistic sort sequence:

SELECT NLS_LOWER
   ('New City', 'NLS_SORT = XFrench')
   FROM DUAL;

Output
------
New City

Synatx For using INSTRC function

INSTRC(string_1, string_2 [, starting_position [, nth_appearance ] ] )

string_1 is the string to search.

string_2 is the substring to search for in string_1.

starting_position is the position in string_1 where the search will start. this field is optional. If omitted, it defaults to 1. The first position in the string is 1. If the starting_position is negative, the function count from back start_position number of characters from the end of string1 and then searches towards the beginning of string1.

nth_appearance is the nth appearance of string2. This argument is optional. If omitted, it defaults to 1.

If string_2 is not found in string_1, then the instr function will return 0.

some examples follow

SQL>SELECT INSTRC(‘John Peter’, ‘n’, 1, 1)
FROM dual;
This query would return 4; the first occurrence of ‘n’

Syntax for using ASCII Function

ASCII(character);

some examples follow

SQL>SELECT ASCII(a) from DUAL;

this query would return 97

SQL>SELECT ASCII(a) from DUAL;

this query would would return 65

Inline comments

Inline Comments begins with a Double hyphen(The single line comment delimiter, ). The comment starts after the hyphen, and includes a single line of text only. If a second line is needed, the following should also include the delimiter at the beginning.

The following example shows use of single line comments

DECLARE
v_emp_name VARCHAR2(50);
BEGIN
– Retrieve the name of a employee into a local variable from employee database
SELECT emp_name
INTO v_emp_name
FROM employees
WHERE emp_id = ’9895678′;
–Prints the employee name to the screen
DBMS_OUTPUT.PUT_LINE(‘The Employee name for employee id 9895678 is: ‘
||v_emp_id);

EXCEPTION
–print exception if any
WHEN OTHERS THEN
DBMS_OUTPUT.PUT_LINE (SQLERRM);
END;
/

Multi Line Comments

anonymous comments of several lines of multi line comment use ‘/*; as a starting comment delimiter and * / ;as a ending comment delimiter. We can use multiline Comments on several lines or paragraphs. They are useful for headings or notes, including version control in the PL / SQL directly. The following example illustrates the multi-line comments in an anonymous block:

/*
Author : MARY PETER
Description : Sample Program to find employee name
*/
DECLARE
v_emp_name VARCHAR2(50);
BEGIN
– Retrieve the name of a employee into a local variable from employee database
SELECT emp_name
INTO v_emp_name
FROM employees
WHERE emp_id = ’9895678′;
–Prints the employee name to the screen
DBMS_OUTPUT.PUT_LINE(‘The Employee name for employee id 9895678 is: ‘
||v_emp_id);

/*
This code will not be executed

UPDATE emp_salary =emp_salary *.23
WHERE emp_name=v_emp_id
*/
EXCEPTION
–print exception if any
WHEN OTHERS
THEN DBMS_OUTPUT.PUT_LINE (SQLERRM);
END;
/

Multiline comments can be used for

■ Header information For PL/SQL scripts
■ Header information For PL/SQL Objects
■ To comment blocks of code. This is useful for the trial or effectively eliminate the code, but allowing for future use of the code
comments that go beyond simple lines
■ For comments that extend beyond single lines

Identifiers

Literals

Delimiters

Comments

Declarations allocate storage space for a value, specify its datatype, and name the storage location so that you can reference it.
As the program executes, the values of variables can change, but the values of constants cannot.

Declaring Variables

To declare simple variable, the format is:

VARIABLE_NAME DATATYPE;

Some examples follow:

DECLARE
v_emp_name VARCHAR2(10);
v_emp_number NUMBER(10);
v_emp_bdate DATE;
BEGIN
–some executable statments using these variables

END;

Assigning values to Variables

To declare some variables and assign values we use := (the assignment operator)

The format is

VARIABLE_NAME DATATYPE := VARIABLE_VALUE;

Some examples follow:

DECLARE
v_emp_name VARCHAR2(20) := ‘PETER’;
v_emp_number NUMBER(10) := 1899891;
BEGIN
–some executable statments using these variables
END;

When the program executes, the values of variables may change.In the below example value of v_emp_number 0 in Declaration,As the program executes the value of v_emp_number change to a value which stored in the database associated with the employee name ‘PETER’

DECLARE
v_emp_name VARCHAR2(20) := ‘PETER’;
v_emp_number NUMBER(10) := 0;
BEGIN
– This Query find employee number associated with the name ‘PETER’ and stores it into variable v_emp_number
SELECT emp_number into v_emp_number
FROM employees
WHERE emp_name=’PETER’;

–This prints the output to the user screen
DBMS_OUTPUT.PUT_LINE(v_emp_number);
END;

OUTPUT
————-
1899891

Declaring constant Variables

A constant variable is a variable that is assigned a value during the declaration using the CONSTANT keyword. A constant variable maintains the same value throughout the life of the procedure. You cannot change the value of a constant outside the declaration. If you try to change the value of a constant outside the declaration section, you will get an error.

To declare a constant,Format is:

VARIABLE_NAME CONSTANT DATATYPE := VARIABLE_VALUE;

Some examples follow:

DECLARE
v_message CONSTANT VARCHAR2(10) := ‘Hello World’;
v_emp_number CONSTANT NUMBER := 123;
BEGIN
–some executable statments that use these variables
END;

The following table lists the delimiters available.

PL/SQL keywords are not case-sensitive, so lower-case letters are equivalent to corresponding upper-case letters.

For eg.emp_sal,EMP_SAL are treated as same.but they are treated diffrently in C,C++ etc

except within string and character literals.

Special Symbols