Keyword & parameter description - expressions, PL-SQL Programming

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Keyword & Parameter Description:

boolean_expression:

This is an expression which yields the Boolean value that is TRUE, FALSE, & NULL.

character_expression:

This is an expression which yields a character or the character string.

date_expression:

This is an expression which yields a date/time value.

numeric_expression:

This is an expression which yields a real value or an integer value.

NOT, AND, OR:

These are the logical operators that follow the tri-state logic. The AND returns the value TRUE only when both its operands are true. The OR returns the value TRUE if either of its operands is true. The NOT returns the reverse value (logical negation) of its operand. The NOT NULL returns NULL as nulls are undetermined

boolean_constant_name:

This identifies a constant of the type BOOLEAN, that must be initialized to the value TRUE, FALSE, & NULL. The Arithmetic operations on Boolean constants are illegal.

boolean_function_call:

This is any of the function call which returns a Boolean value.

boolean_literal:

This is the predefined value that is; TRUE, FALSE, or NULL (that stands for an unknown, missing, or inapplicable value). You can't insert the value TRUE or FALSE into the database column.

boolean_variable_name:

These identify a variable of the type BOOLEAN. The values TRUE, FALSE, and NULL can only be assigned to a BOOLEAN variable. You cannot select or fetch the column values into a BOOLEAN variable. The arithmetic operations on BOOLEAN variables are also illegal.

relational_operator:

This operator allows you to compare the expressions.

IS [NOT] NULL:

This comparison operator proceeds the Boolean value TRUE whenever its operand is null, or FALSE when its operand is not null.

[NOT] LIKE:

These comparison operators compare a character value to a pattern. The Case is significant. The LIKE returns the Boolean value TRUE when the character patterns equivalent or FALSE if they do not match.

Pattern:

This is a character string compare by the LIKE operator to the specified string value. It can involve two special-purpose characters known as the wildcards. An underscore (_) match exactly one character; a percent sign (%) match zero or more characters.

[NOT] BETWEEN:

This comparison operator tests whether a value lies in the specific range. That means "The bigger than or equal to minimum value & less than or equivalent to the maximum value."

[NOT] IN:

This comparison operator tests the set membership. That means "equivalent to any member of." The set can encompass only nulls, but they are ignored. Also, the expressions of the form value NOT IN set yield FALSE whenever the set contains a null.

cursor_name:

This identifies an explicit cursor formerly declared within the present scope.

cursor_variable_name:

This identifies the PL/SQL cursor variable formerly declared within the present scope.

host_cursor_variable_name:

This identifies a cursor variable declared in the PL/SQL host atmosphere and passed to the PL/SQL as a bind variable. The Host cursor variables should be prefixed with a colon.

SQL:

This identifies a cursor opened implicitly by the Oracle to process the SQL data manipulation statement. The implicit SQL cursor forever refers to the most newly executed SQL statement.

%FOUND, %ISOPEN, %NOTFOUND, %ROWCOUNT:

These are the cursor attributes. When appended to the name of the cursor or cursor variable, these attributes return helpful information about the execution of a multi-row query. You can also add them to the implicit the SQL cursor.

EXISTS, COUNT, FIRST, NEXT, LAST, LIMIT, PRIOR:

These are the collection methods. When appended to the name of the collection, these methods return helpful information. For illustration, the EXISTS(n) returns TRUE if the nth element of a collection exists. Or else, the EXISTS(n) returns FALSE.

Index:

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

host_variable_name:

This identifies a variable declared in the PL/SQL host atmosphere and passed to the PL/SQL as a bind variable. The datatype of the host variable should be implicitly convertible to the suitable PL/SQL datatype. Also, the host variables should be prefixed with a colon.

indicator_name:

This identifies an indicator variable declared in the PL/SQL host atmosphere and passed to PL/SQL. The Indicator variables should be prefixed with a colon. Indicator variables "indicate" the value or the condition of its related host variable. For illustration, in the Oracle Precompiled atmosphere, the indicator variables can detect nulls or truncated values in the output host variables.

numeric_constant_name:

This identifies a formerly declared constant which stores a numeric value. It should be initialized to a numeric value or a value implicitly convertible to the numeric value.

numeric_function_call:

This is a function call which returns a numeric value or a value implicitly convertible to the numeric value.

numeric_literal:

This is a literal which represents a numeric value or a value implicitly convertible to the numeric value. 

collection_name:

This identifies the index-by table, nested table, or varray formerly declared within the present scope.

numeric_variable_name:

This identifies a formerly declared variable which stores a numeric value.

NULL:

This keyword presents a null; it stands for an unknown, missing, or inapplicable value. When NULL is used in the numeric or date expression, then the result is a null.

Exponent:

This is an expression which should results a numeric value.

-,+, /, *, **

These symbols are the subtraction, addition, division, multiplication, and exponentiation operators, correspondingly.

character_constant_name:

This identifies a formerly declared constant which stores a character value. It should be initialized to a character value or a value implicitly convertible to the character value.

character_function_call:

This is a function call which returns a character value or a value implicitly convertible to the character value.

character_literal:

This is a literal which represents a character value or a value implicitly convertible to the character value.

character_variable_name:

This identifies a formerly declared variable which stores a character value.

||:

This is a concatenation operator. As the illustration below shows, the result of concatenating string1 with string2 is a character string which contains the string1 followed by the string2:

'Good' || ' morning!' = 'Good morning!'

The next illustration shows that the nulls have no effect on the result of the concatenation:

'suit' || NULL || 'case' = 'suitcase'

A null string (''), that is zero characters in length, is treated like a null.

date_constant_name:

This identifies a formerly declared constant which stores a date value. It should be initialized to a date value or a value implicitly convertible to the date value.

date_function_call:

This is a function call which returns a date value or a value implicitly convertible to the date value.

date_literal:

This is a literal which represents a date value or a value implicitly convertible to the date value.

date_variable_name:

This identifies a formerly declared variable which stores a date value.


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