Read statement [Revelation On-Line Wiki]

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====== Read statement ======


 
==== Description ====
 
Reads a record from a native table, assigning the record to the specified variable.
 
==== Syntax ====
 
**Read** //variable// From [//table_var//  Cursor //cursorvar//], //key// Then | Else //statements//
 
==== Parameters ====
 
The Read statement has the following parameters.

^Parameter^Description^
|//Variable//|Assigned the value of the data that is read from the row specified by key.|
|//Table_var//|A table variable created by a previous [[open|Open statement]].|
|//Cursorvar//|If accessing a cursor, //cursorvar// contains a cursor variable. Cursor variables are initialized with a [[select_by|Select...By statement]] and must be preceded with the word Cursor.\\ If the table being accessed has had control features added, cursor access will automatically invoke domain conversion during a Read.|
|//Key//|The row referenced by //key// will be read from the table identified by //table_var// or the table accessed using the cursor in //cursorvar//.|
|Then|The statement(s) following Then are executed if a row key is read successfully.|
|Else|The statement(s) following Else are executed if the row in //variable// cannot be read. The [[status|Status() function]] indicates the severity of the error, and the system variable @FILE_ERROR contains details about the nature of the error.||

 
==== See Also ====
 
[[open|Open]], [[reado|ReadO]], [[readv|ReadV]], [[matread|MatRead]], [[write|Write]].
 
==== Example ====
 
<code>
/* The row having key 101 is read into the variable CUST as a dynamic array. */
open "CUSTOMER" To CUSTOMER_TABLE then 
  read CUST From CUSTOMER_TABLE, "101" else
     status = Set_FSError()
     return
  end
end

/* Select...By initializes a Cursor with a sorted list of customer records. A ReadNext and Read loop reads each record in turn, passing the customer records to a local subroutine (not shown) for processing. Note the use of the Cursor keyword and the
Cursorvar. */
 

CURSOR_NO = ""
Select CUSTOMER_TABLE By "ST" Setting CURSOR_NO Else
  status = Set_FSError()
  Return
end
Done = 0
loop
  ReadNext @ID Using CURSOR_NO else Done = 1
Until Done Do 
  read @RECORD From CUSTOMER_TABLE, @ID then
     status = Set_FSError()
     return
  end
  * processing logic here ...
  GoSub PROCESS
Repeat
</code>