u_condition

Provide a DBMS-independent profile for selection in read and selectdb statements.

u_condition  (SelectionExpression)

Example: read u_condition(vConditions)

Parameters

Parameters
Parameter Data Type Description
SelectionExpression String Conditional expression used as a retrieve profile, in which:
  • The left-side operand must be a field in the retrieved entity.
  • The right-side operand can be a value or a function returning a value.

    If a ProcScript function is used, it must be allowed in the component type of the component where the SelectionExpression is executed. For example $fieldmod is only allowed in a Form.

  • Neither operand can contain yet another expression.

Return Values

For values returned in $status, see read or show, as appropriate. For more information, see read and selectdb.

Values Commonly Returned in $procerror Following the u_condition Clause
Value

Error constant

Meaning
-1301 <UPROCERR_SYNTAX> Syntax error.
-1302 <UPROCERR_SERVICE> Function not allowed in service.

-1303

<UPROCERR_REPORT> Function not allowed in report.
-1304 <UPROCERR_UNKNOWN_CONTEXT> Function not allowed, unknown context.
-1305 <UPROCERR_EXPRESSION> Expression not allowed.
-1306 <UPROCERR_CONDITION> Condition not allowed.
-1307 <UPROCERR_EXTRACTION_EXPR> Extraction expression is a condition.
-1308 <UPROCERR_INDIRECTION> Indirection followed by brackets.
-1309 <UPROCERR_PARENTHESES> Operand followed by parentheses.
-1310 <UPROCERR_BRACKETS> Operand followed by square brackets.
-1311 <UPROCERR_UNRESOLVED_OPERAND> A field, parameter, or variable could not be found in current context.

Use

Allowed in all component types.

Description

You can use the u_condition clause with read or selectdb ProcScript statements to provide a runtime retrieve profile for selecting data.

Note:  u_condition cannot be used with u_where. The u_where and u_condition clauses are very similar. However, the u_condition clause is interpreted at run time, whereas u_where is interpreted at compilation.

The SelectionExpression generated from the u_condition clause is passed to the DBMS connector. This data is limited to 8192 bytes. In addition, a maximum of 45 retrieve profile characters can be entered, which includes those on the u_conditionand those entered in fields by the user; if the search profile of a single field exceeds 512 bytes, it is truncated to 512 bytes.

Using u_condition

When defining an expression in ProcScript, follow the rules for string substitution, which uses %% to include operators and quotation marks. For more information, see Substitution in String Values. For example:

$uconditions$ = "fld_date >= $date(%%"22-APR-17%%")"

When expressions are provided by the end-user (for example, in a profile field), this is not required. For example, the following expressions could be entered by an end-user, where the right-side operand (fld_xxxx) are fields of an entity in the component:

fld_numeric > 1 & fld_numeric < 6
fld_string = $uppercase("amsterdam")
fld_string = userdefinedfunction(FLD_STRING)
fld_boolean = 0
fld_boolean = "F"
fld_date >= $date("22-APR-17")
fld_date >= "20170422"
fld_time >= $clock("05:06:07")
fld_time >= "050607"


;22 April 2017 05 hours 06 minutes 07 seconds:

fld_datetime >= $datim("22-APR-17 05:06:07") 
fld_datetime >= 2017042205060700

u_condition is interpreted at runtime, so the value of the $uconditions$ component variable in the following example provides a variable retrieve profile. 

; read trigger of Entity Service component
trigger read
   read u_condition($uconditions$)
end

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