Oracle sql developer declare variable1/10/2024 ![]() Local variables − Variables declared in an inner block and not accessible to outer blocks. However, if a variable is declared and accessible to an outer block, it is also accessible to all nested inner blocks. If a variable is declared within an inner block, it is not accessible to the outer block. PL/SQL allows the nesting of blocks, i.e., each program block may contain another inner block. When the above code is executed, it produces the following result − Try the following example which makes use of various types of variables −ĭbms_output.put_line('Value of c: ' || c) ĭbms_output.put_line('Value of f: ' || f) ![]() It is a good programming practice to initialize variables properly otherwise, sometimes programs would produce unexpected results. If you use the NOT NULL constraint, you must explicitly assign an initial value for that variable. You can also specify that a variable should not have a NULL value using the NOT NULL constraint. Greetings varchar2(20) DEFAULT 'Have a Good Day' If you want to initialize a variable with a value other than the NULL value, you can do so during the declaration, using either of the following − Whenever you declare a variable, PL/SQL assigns it a default value of NULL. Constrained declarations require less memory than unconstrained declarations. When you provide a size, scale or precision limit with the data type, it is called a constrained declaration. Some valid variable declarations along with their definition are shown below − Where, variable_name is a valid identifier in PL/SQL, datatype must be a valid PL/SQL data type or any user defined data type which we already have discussed in the last chapter. When you declare a variable, PL/SQL allocates memory for the variable's value and the storage location is identified by the variable name. PL/SQL variables must be declared in the declaration section or in a package as a global variable. For this chapter, let us study only basic variable types. which we will cover in subsequent chapters. PL/SQL programming language allows to define various types of variables, such as date time data types, records, collections, etc. You cannot use a reserved PL/SQL keyword as a variable name. By default, variable names are not case-sensitive. The name of a PL/SQL variable consists of a letter optionally followed by more letters, numerals, dollar signs, underscores, and number signs and should not exceed 30 characters. Each variable in PL/SQL has a specific data type, which determines the size and the layout of the variable's memory the range of values that can be stored within that memory and the set of operations that can be applied to the variable. A variable is nothing but a name given to a storage area that our programs can manipulate. In this chapter, we will discuss Variables in Pl/SQL.
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