MOM Helpers Online Help - XBASE Expression Builder

MOM Helpers Online Help

XBASE Expression Builder

General Information

This utility helps you build XBASE expressions with a "pick and choose" menu for functions, fields, and variables. An expression can be as simple as a field name or as complex as a calculation involving immediate IF functions, concatenations, and data type conversions. The main purpose of the Expression Builder is to facilitate the creation of expressions by providing you with lists of appropriate options each step of the way.

How to Use the Screen

To create an expression, you can type it directly into the expression box, or you can select items from the functions drop-down lists in the dialog box to have the utility paste them into the expression box for you.

You might find some of the following functions useful when manipulating strings in expressions.

If you want to...	then use this function
Remove leading & trailing blanks from character expressions	ALLTRIM( )
Remove leading blanks	LTRIM( )
Remove trailing blanks	RTRIM( )
Add specified characters to the left, right, both sides of a string	PADL( ), PADR( ), PADC( )
Work with parts of a character string for comparisons	SUBSTR( )
Use a specified number of characters starting left of a string	LEFT( )
Use a specified number of characters starting right of a string	RIGHT( )
Change uppercase to lowercase, or lowercase to uppercase	UPPER( ), LOWER( )
Convert a string to initial capitals	PROPER( )
Have a numeric field interpreted as a character string	STR( )

Functions

Contains list boxes of four function types. When you select a function from one of the four types, it is automatically pasted into the expression box. When you are building expressions for remote views, only the functions specific to the target back-end data are listed.

String - Lists available character string functions.

Logical - Lists available logical functions.

Math - Lists available math functions.

Date - Lists available date and time functions.

Expression

Displays the expression that you are creating or editing.

Fields

Lists the fields in the current table or view.

To paste a field into the expression box, either double-click the field or select the field and press ENTER.

To display fields from a different table, select a different table in the From Table box.

From Table

Lists tables and views that are open. Select a table or view to update the Fields box.

Variables

Lists system memory variables, arrays, and memory variables that you have created.

To paste a variable into the expression box, either double-click the variable or select the variable and press ENTER.

The VERIFY Button

Validates the syntax of the expression in the expression box. If the expression is valid, "Expression is valid" is displayed in the status bar. If it is not valid, an error message is displayed. This option is not enabled for remote views.

Note If you include a user-defined function call in the expression, Verify will indicate an error, but there will not necessarily be an error when the expression is evaluated at run time.

The OPTIONS Button

Displays the Expression Builder Options dialog box, in which you can set preferences for the Expression Builder.

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