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 Data Manipulation (DML) StatementsBuilt-in Scalar Functions 

DECLARE VARIABLE

Declares a local variable

Syntax
DECLARE [VARIABLE] varname
  <domain_or_non_array_type> [NOT NULL] [COLLATE collation]
  [{DEFAULT | = } <initvalue>];

<domain_or_non_array_type> ::=
  !! See Scalar Data Types Syntax !!

<initvalue> ::= <literal> | <context_var>
Table 1. DECLARE VARIABLE Statement Parameters
Argument Description

varname

Name of the local variable

collation

Collation

initvalue

Initial value for this variable

literal

Literal of a type compatible with the type of the local variable

context_var

Any context variable whose type is compatible with the type of the local variable

The statement DECLARE [VARIABLE] is used for declaring a local variable.One DECLARE [VARIABLE] statement is required for each local variable.Any number of DECLARE [VARIABLE] statements can be included and in any order.The name of a local variable must be unique among the names of local variables and input and output parameters declared for the module.

A special case of DECLARE [VARIABLE] — declaring cursors — is covered separately in [fblangref50-psql-declare-cursor]

Data Type for Variables

A local variable can be of any SQL type other than an array.

  • A domain name can be specified as the type;the variable will inherit all of its attributes.

  • If the TYPE OF domain clause is used instead, the variable will inherit only the domain’s data type, and, if applicable, its character set and collation attributes.Any default value or constraints such as NOT NULL or CHECK constraints are not inherited.

  • If the TYPE OF COLUMN relation.column option is used to “borrow” from a column in a table or view, the variable will inherit only the column’s data type, and, if applicable, its character set and collation attributes.Any other attributes are ignored.