System accepts inputs from user through SELECTION CRITERIA.
Selection criteria are nothing but input fields which allows the user to restrict information given to program for processing further data. If you don’t specify any criteria for selection, your report program produces a long list of data, which might not be needed by the user. Basically, selection criteria are the fields where user enters some value for which he needs information. Through selection criteria user can enter discrete value or ranges. For example, user wants to see all the records of the employees, who have joined between 12th December 1997 and 12th May 1998. This range can be entered in selection criteria. As the user becomes more specific for mentioning the criteria, the list will be smaller and more specific.
Syntax:
SELECT-OPTIONS
for .
Field is the variable, which you declare for accepting input from the user.
Table field is reference field.
SELECT-OPTIONS: fld1 for sflight-fldate,
carrid1 for sflight-carrid.
Maximum length of the name Select-Options variable is 8.
When system executes this statement, the selection screen is displayed and is like this.
When you enter the desired information and click on execute button, rest of the program is executed, that is retrieval of data from database, which matches this information and the list is displayed.
Behavior of SELECT-OPTIONS
When the Select-Options statement is executed the system creates the internal table with the same variable name (in this case it will be carrid1). This table is also called as selection table. The main purpose of selection table is to store selection criteria. The table has four standard fields, which are as follows:
• SIGN is a variable, which denotes the system whether the result should be included with those particular criteria. It can contain either I or E. I denotes Inclusion. The criteria are included.
E denotes Exclusion. The criteria are excluded from the result.
• LOW the data type of LOW is the same as the field type of the database table, for which you are using selection criteria. This acts as lower limit of the selection.
• HIGH the data type of HIGH is the same field type of the database table, for which you are using the selection criteria. This acts as higher limit. If you don’t enter HIGH value then the LOW value defines a single value selection.
• OPTION is two-character field, which contains operators like EQ, GT, LT, GE, and LE.
When the user enters both the values i.e., high and low then this field acts as BT (between). If you don’t enter high value then all other operators can be Applicable.
For each Select-Options statement system creates internal table.
Default values for select-options
If you want to display default values for the selection criteria before your screen is displayed, give default values for the selection table fields i.e., low or high.
SELECT-OPTIONS: CARRID1 FOR SFLIGHT-CARRID DEFAULT CARRID1-LOW = ‘LH’ AND CARRID1-HIGH = ‘SQ’.
In this case selection screen is displayed with default values ‘LH’ for lower range and ‘SQ’ for higher range. User can use same values or overwrite these values with new values, whichever he needs.
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