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Declarations in SQLYour program stores values in the variables and constants. As the program executes, the value of the variables can change, but the values constants cannot. You can declare the variables and constants in the declarative part of any PL/SQL block, package, or subprogram. The Declarations allocate the storage space for a value, state its datatype, and name the storage location and hence, you can reference it. A couple of examples are shown below: birthday DATE;emp_count SMALLINT := 0;The first declaration names a variable of the type DATE. The second declaration names a variable of the type SMALLINT and uses the assignment operator to assign an initial value of zero to the variable. The example next show that the expression following the assignment operator can be arbitrarily complex and can refer to the earlier initialized variables: pi REAL := 3.14159;radius REAL := 1;area REAL := pi * radius**2; By default, the variables are initialized to NULL. So, these declarations are equal: birthday DATE;birthday DATE := NULL; In the declaration of a constant, the keyword CONSTANT should precede the type of the specifier, as the example below shows: credit_limit CONSTANT REAL := 5000.00; This declaration names a constant of the type REAL and assigns an initial value of 5000 to the constant. The constant must be initialized in its declaration. Or else, you get a compilation error whenever the declaration is elaborated. (The procedure of a declaration by the PL/SQL compiler is known as the elaboration.)
Interesting properties of CROSS JOIN - SQL Compare these with the "interesting properties of JOIN", CROSS JOIN is associative but not commutative. Unlike JOIN and NATURAL JOI
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Parameter and Keyword Description: label_name: This is an undeclared identifier which optionally labels a loop. When used, the label_name should be enclosed by double ang
Natural Join - SQL In the absence of NATURAL JOIN Example has to be replaced by something rather more longwinded, as shown in Example. Example: Joining IS_CALLED and IS_EN
Example of GROUP BY and COLLECT Operator Example: Using GROUP BY and COLLECT to obtain C_ER2 SELECT CourseId, CAST ( COLLECT (ROW (StudentId, Mark)) AS ROW (Studen
(a) What are decision support systems, and what role do they play in the business environment? (b) Data warehousing is defined as "a subject-oriented, integrated, non-volatile c
Parameter and Keyword Description: table_reference: This identifies a table or view which should be available when you execute the INSERT statement, and for that you sho
Using NOT NULL Besides assigning an initial value, the declarations can impose the NOT NULL constraint, as the example below shows: acct_id INTEGER(4) NOT NULL := 9999; You ca
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Difference between 9i & 10G When Oracle releases any new databases then it are having some discrepancy with them. But 10G is having much difference than oracle 9i has. Oracle
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