Syntax for SQL Expression Types

An expression is a combination of one or more values, operators, and SQL functions that evaluate to a value. An expression generally assumes the data type of its components.

Expressions have several forms. The sections that follow show the syntax for each form of expression. Refer to Chapter 5, "Subclauses" for the syntax of the subclauses.

CASE expressions

CASE { simple_case_expression
     | searched_case_expression
     }
     [ else_clause ]
     END

Column expressions

A column expression can be a simple expression, compound expression, function expression, or expression list, containing only columns of the subject table, constants, and deterministic functions.

Compound expressions

{ (expr)
| { + | - | PRIOR } expr
| expr { * | / | + | - | || } expr
}

Note: The double vertical bars are part of the syntax
      (indicating concatenation) rather than BNF notation.

CURSOR expressions

CURSOR (subquery)

Datetime expressions

expr AT
   { LOCAL
   | TIME ZONE { ' [ + | - ] hh:mi'
               | DBTIMEZONE
               | 'time_zone_name'
               | expr
               }
   }

Function expressions

You can use any built-in SQL function or user-defined function as an expression.

Interval expressions

( expr1 - expr2 )
   { DAY [ (leading_field_precision) ] TO
     SECOND [ (fractional_second_precision) ]
   | YEAR [ (leading_field_precision) ] TO
     MONTH
   }

Model expressions

{ measure_column [ { condition | expr } [, { condition | expr } ]... ]
| aggregate_function 
     { [ { condition | expr } [, { condition | expr } ]... ]
     | [ single_column_for_loop [, single_column_for_loop ]... ]
     | [ multi_column_for_loop ]
     }
| analytic_function
}

Object access expressions

{ table_alias.column.
| object_table_alias.
| (expr).
}
{ attribute [.attribute ]...
  [.method ([ argument [, argument ]... ]) ]
| method ([ argument [, argument ]... ])
}

Placeholder expressions

:host_variable
   [ [ INDICATOR ]
     :indicator_variable
   ]

Scalar subquery expressions

A scalar subquery expression is a subquery that returns exactly one column value from one row.

Simple expressions

{ [ query_name.
  | [schema.]
    { table. | view. | materialized view. }
  ] { column | ROWID }
| ROWNUM
| string
| number
| sequence. { CURRVAL | NEXTVAL }
| NULL
}

Type constructor expressions

[ NEW ] [ schema. ]type_name
   ([ expr [, expr ]... ])