expression:
 case-expression
| constant
| [correlation-name.]column-name
| - expression
| expression operator expression
| ( expression )
| function-name ( expression, ... )
| if-expression
| special value
| input-parameter

case-expression:
CASE expression
WHEN expression
THEN expression,...
[ ELSE expression ]
END

alternative form of case-expression:
CASE
WHEN search-condition
THEN expression,...
[ ELSE expression ]
END

constant:
 integer  | number  | string | host-variable

special-value:
 CURRENT { DATE  |  TIME  |  TIMESTAMP  }
| NULL
| SQLCODE
| SQLSTATE

if-expression:
IF condition
THEN expression
[ ELSE expression ]
ENDIF

input-parameter:
{ ? | :name [ : indicator-name ] }

operator:
{  +  |  -  |  *  |  /  |  ||  |  % }

• 式内の定数
• Ultra Light の特別値
• 式内のカラム名
• Ultra Light SQL 関数
• 式のサブクエリ
• Ultra Light の探索条件
• Ultra Light のデータ型
• CASE 式
• 入力パラメーター