Assignment Statement

An assignment statement sets the current value of a variable, field, parameter, or element. The statement consists of an assignment target followed by the assignment operator and an expression. When the statement is executed, the expression is evaluated and the resulting value is stored in the target. For more information, see "Variable Assignment".

Syntax

Text description of the illustration assignment_statement.gif

Keyword and Parameter Description

attribute_name

This identifies an attribute of an object type. The name must be unique within the object type (but can be reused in other object types). You cannot initialize an attribute in its declaration using the assignment operator or DEFAULT clause. Also, you cannot impose the NOT NULL constraint on an attribute.

collection_name

This identifies a nested table, index-by table, or varray previously declared within the current scope.

cursor_variable_name

This identifies a PL/SQL cursor variable previously declared within the current scope. Only the value of another cursor variable can be assigned to a cursor variable.

expression

This is an arbitrarily complex combination of variables, constants, literals, operators, and function calls. The simplest expression consists of a single variable. For the syntax of expression, see "Expressions". When the assignment statement is executed, the expression is evaluated and the resulting value is stored in the assignment target. The value and target must have compatible datatypes.

field_name

This identifies a field in a user-defined or %ROWTYPE record.

host_cursor_variable_name

This identifies a cursor variable declared in a PL/SQL host environment and passed to PL/SQL as a bind variable. The datatype of the host cursor variable is compatible with the return type of any PL/SQL cursor variable. Host variables must be prefixed with a colon.

host_variable_name

This identifies a variable declared in a PL/SQL host environment and passed to PL/SQL as a bind variable. Host variables must be prefixed with a colon.

index

This is a numeric expression that must yield a value of type BINARY_INTEGER or a value implicitly convertible to that datatype.

indicator_name

This identifies an indicator variable declared in a PL/SQL host environment and passed to PL/SQL. Indicator variables must be prefixed with a colon. An indicator variable "indicates" the value or condition of its associated host variable. For example, in the Oracle Precompiler environment, indicator variables let you detect nulls or truncated values in output host variables.

object_name

This identifies an object (instance of an object type) previously declared within the current scope.

parameter_name

This identifies a formal OUT or IN OUT parameter of the subprogram in which the assignment statement appears.

record_name

This identifies a user-defined or %ROWTYPE record previously declared within the current scope.

variable_name

This identifies a PL/SQL variable previously declared within the current scope.

Usage Notes

By default, unless a variable is initialized in its declaration, it is initialized to NULL every time a block or subprogram is entered. So, never reference a variable before you assign it a value.

You cannot assign nulls to a variable defined as NOT NULL. If you try, PL/SQL raises the predefined exception VALUE_ERROR.

Only the values TRUE, FALSE, and NULL can be assigned to a Boolean variable. When applied to an expression, the relational operators return a Boolean value. So, the following assignment is legal:

DECLARE
   out_of_range BOOLEAN;
   ...
BEGIN
   ...
   out_of_range := (salary < minimum) OR (salary > maximum);

As the next example shows, you can assign the value of an expression to a specific field in a record:

DECLARE
   emp_rec emp%ROWTYPE;
BEGIN
   ...
   emp_rec.sal := current_salary + increase;

Moreover, you can assign values to all fields in a record at once. PL/SQL allows aggregate assignment between entire records if their declarations refer to the same cursor or table. For example, the following assignment is legal:

DECLARE
   emp_rec1 emp%ROWTYPE;
   emp_rec2 emp%ROWTYPE;
   dept_rec dept%ROWTYPE;
BEGIN
   ...
   emp_rec1 := emp_rec2;

Using the following syntax, you can assign the value of an expression to a specific element in a collection:

collection_name(index) := expression;

In the following example, you assign the uppercase value of last_name to the third row in nested table ename_tab:

ename_tab(3) := UPPER(last_name);

Examples

Several examples of assignment statements follow:

wages := hours_worked * hourly_salary;
country := 'France';
costs := labor + supplies;
done := (count > 100);
dept_rec.loc := 'BOSTON';
comm_tab(5) := sales * 0.15;

Related Topics

Constants and Variables, Expressions, SELECT INTO Statement