Icon ODBC - Function Reference

dbselect()

Description: selects a rowset from a table

Syntax: dbselect(f [, [columns] [, [criteria] [, [order]]]])

Parameters:

f: ODBC file previously opened with open()
columns: list of columns to retrieve. If columns is "*" or a null string or not specified all columns in the table are selected.
criteria: search condition string. If criteria is a null string or not specified all rows are selected.
order: column(s) by which the result set will be sorted.

Examples
Suppose we want to perform the following SQL query on table f:

SELECT * FROM f

Using dbselect() we can do this in several ways:

dbselect(f,"*")
dbselect(f,"")
dbselect(f,,,)
dbselect(f)

SELECT name FROM f

can be written using dbselect() as:

dbselect(f,"name")
dbselect(f,"name",,)

SELECT name FROM f ORDER BY id

is equivalent to:

dbselect(f,"name",,"id")
dbselect(f,"name","","id")

SELECT id, name FROM f WHERE id > 100 ORDER BY name

would be written as:

dbselect(f,"id,name","id > 100","name")

Code Example

procedure main()
 f:=open("mysql","O","test","fbalbi","mypasswd") # open test table

 # select columns 'name', 'id', 'amt' from test
 # rowset is made of rows with name='Federico'
 # and order the rowset by due date

 r:=dbselect(f, "id, name, amt, paid, due","name='Federico'","due")

 write(*f, " row(s) selected") # may not work with some DBMS

 rec:=fetch(f) # retrieve first record in the rowset

 every i:=(1 to *rec) do  # write record fields values
   write("[", rec[i], "]")

 close(f) # close table
end