LogiView

Where Clauses with Comparison Operators

     

This syntax may be used for the definition of a LogiView variable database access and as an argument for 'where', 'where_ent', and 'where_ent2' commands.

 

Syntax:

 

{STR_EXPR}{WHR_CMP}{EXPR}

 

{STR_EXPR}

String expression with the name of a table field in the form 'table name.column name'.

 

{WHR_CMP}

         

Comparison operator:

> greater
< smaller than
= equal to
<> not equal to
>= greater or equal to
<= smaller or equal to
 

{EXPR}

Expression of the comparison value analog to the type of table field.

 
 

Example 1: WHERE clauses with numerical expression as comparison value

 

Definition of a selection condition as argument of a 'where' command (part of the combined select instruction):

where("MAT.MAX_WIDTH" >= 5*CON1)
  Result:
 

All records of the "MAT" table are selected, whose "MAX_WIDTH" field contents is greater then or equal to the expression '5*CON1' ("CON1" is a variable or constant of type integer or float).

 

Example 2: WHERE clauses with string expression as comparison value

 

Assignment to integer variable NR by using the 'sel_value' function in the action part of a decision table:

NR=sel_value("Mat.ID_NO","MAT.NAME"="maho-%")
  Result:
  The NR integer variable is defined with the contents of the "ID_NO" field from a record in the WRK database table. The "NAME" string field of the selected record matches the pattern 'maho-%', i.e. a string of arbitrary size starting with "maho-".

If more than one record exists matching this Where clause, a selection menu with all matches is displayed.

 

Example 3: WHERE clauses with logical expression as comparison value

 

Definition of the database access for the float variable F1 (in the variable declaration table):

Name T ... Database access ...
F1 I ... "WRK.MAX_Y", "WRK.STANDARD" = TRUE ...
  Result:
 

Using the float variable F1, you may access the "MAX_Y" (float) field of those records in the "WRK" database table, whose "STANDARD" (logic) field contains the value TRUE.

The value TRUE is represented by a in DataView lists.