Queries

Introduction

The examples will be based on a copy of the demo database Sports 2000 provided with the setup of Progress.

When working with queries in Progress you need to:

DEFINE the query and set what buffers (tables) and fields it works against.

OPEN the query with a specific WHERE-clause that defines how to retrieve the records. Possibly also sorting (BY/BREAK BY)

GET the actual data - that can be the FIRST, NEXT, PREV (for previous) or LAST matching record.

Syntax

  • DEFINE QUERY query-name FOR buffer-name. //General query definition for one buffer
  • DEFINE QUERY query-name FOR buffer-name1, buffer-name2. //Joining two buffers
  • DEFINE QUERY query-name FOR buffer-name FIELDS (field1 field2). //Only retreive field1 and field2
  • DEFINE QUERY query-name FOR buffer-name EXCEPT (field3). //Retreive all fields except field3.

Basic Query

/* Define a query named q1 for the Customer table */
DEFINE QUERY q1 FOR Customer.
/* Open the query for all Customer records where the state is "tx" */
OPEN QUERY q1 FOR EACH Customer WHERE Customer.state ='TX'.                                                                                                                                                                               
/* Get the first result of query q1 */
GET FIRST q1.                                                                                                                                                                                                                   

/* Repeat as long as query q1 has a result */
DO WHILE NOT QUERY-OFF-END('q1'):          
    /* Display Customer.Name in a frame called frame1 with 10 rows */
    DISPLAY Customer.Name WITH FRAME frame1 10 DOWN.
    /* Move down the target line where to display the next record */
    DOWN WITH FRAME frame1.
    /* Get the next result of query q1 */
    GET NEXT q1.
END.
/* Display how many results query q1 had. */
DISPLAY NUM-RESULTS('q1') LABEL "Number of records".

/* Close the query */
CLOSE QUERY q1.                                              

Output (third screen in Windows gui):

enter image description here

Moving poisition withing a query using next, first, prev and last

DEFINE QUERY q1 FOR Customer.

OPEN QUERY q1 FOR EACH Customer.

GET FIRST q1.

loop:
REPEAT:
    IF AVAILABLE Customer THEN DO:
        DISPLAY Customer.NAME CustNum WITH FRAME frClient TITLE "Client data".
        
        DISPLAY
            "(P)revious" SKIP 
            "(N)ext" SKIP
            "(F)irst" SKIP
            "(L)ast" SKIP
            "(Q)uit" SKIP
            WITH FRAME frInstr
                TITLE "Instructions".
    END.
    
    READKEY.

    IF LASTKEY = ASC("q") THEN LEAVE loop.
    ELSE IF LASTKEY = ASC("n") THEN
        GET NEXT q1.
    ELSE IF LASTKEY = ASC("p") THEN
        GET PREV q1.
    ELSE IF LASTKEY = ASC("l") THEN
        GET LAST q1.
    ELSE IF LASTKEY = ASC("f") THEN
        GET FIRST q1.

END.

MESSAGE "Bye" VIEW-AS ALERT-BOX.

Multi-Tables Query

This query will join three tables: Customer, Order and Orderline.

The use of the OF statement as in childtable OF parenttable assumes that indexes are constructed in a specific way. That is the case in the sports2000-database.

DEFINE QUERY q1 FOR Customer, Order, Orderline.

OPEN QUERY q1 FOR EACH Customer WHERE Customer.state = 'TX'
    , EACH Order OF customer WHERE order.custnum < 1000
    , EACH orderline OF order.

GET FIRST q1.
DO WHILE NOT QUERY-OFF-END('q1'):
    DISPLAY Customer.Name Order.OrderNum OrderLine.LineNum 
        WITH FRAME frameA 20 DOWN.
    DOWN WITH FRAME frameA.
    GET NEXT q1.
END.

CLOSE QUERY q1.

Result: In Windows GUI:

enter image description here



2017-01-02
2017-01-19
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