Using variables in PLSQL SELECT statement

Question

I have a query that queries on ReportStartDate and ReportEndDate so I thought I would use variables in PLSQL. Not sure what I am missing here, but I get an error:

CLEAR;
DECLARE
    varReportStartDate Date := to_date('05/01/2010', 'mm/dd/yyyy');
    varReportEndDate Date := to_date('05/31/2010', 'mm/dd/yyyy');
BEGIN

    SELECT 
          'Value TYPE', 
          1 AS CountType1, 
          2 AS CountType2, 
          3 AS CountType3 
    FROM DUAL;

    SELECT COUNT (*) 
    FROM CDR.MSRS_E_INADVCH

    WHERE 1=1
    AND ReportStartDate = varReportStartDate 
    AND ReportEndDate = varReportEndDate 
    ;
END;
/

The Error is:

Error starting at line 2 in command:
Error report:
ORA-06550: line 6, column 5:
PLS-00428: an INTO clause is expected in this SELECT statement
ORA-06550: line 8, column 5:
PLS-00428: an INTO clause is expected in this SELECT statement
06550. 00000 -  "line %s, column %s:\n%s"
*Cause:    Usually a PL/SQL compilation error.
*Action:

This happens in Toad as well as in SQL Developer.

What is the proper way of using the variables in my WHERE clause?

Solution 1

You cannot use SQL statements directly in a PL/SQL block ( unless you use EXECUTE IMMEDIATE). The columns will need to be fetched into variables ( which is what PL/SQL is telling you with PLS-00428: an INTO clause is expected in this SELECT statement error). So you'll have to rewrite your statements as below.

SELECT 
      'Value TYPE', 
      1 AS CountType1, 
      2 AS CountType2, 
      3 AS CountType3 
INTO 
     V_VALUE_TYPE,
     V_CountType1,
     V_CountType2,
     V_CountType3
FROM DUAL;

SELECT COUNT(*) 
   INTO V_COUNT    
FROM CDR.MSRS_E_INADVCH
WHERE 1=1
AND ReportStartDate = varReportStartDate 
AND ReportEndDate = varReportEndDate 

Be sure to add Exception Handlers, since PL/SQL expects only 1 row to be returned. If the statement returns no rows, you'll hit a NO_DATA_FOUND exception - and if the statement fetches too many rows, you'll hit a TOO_MANY_ROWS exception.

Solution 2

The question you have to answer is what do you want to do with the data that has been selected?

Sathya gave you one approach - declare variables in your PL/SQL block and select the columns INTO those variables. Note that this requires that the SELECT statement returns exactly one row - any more or less rows will throw an error. Another way is to declare collection types using the BULK COLLECT option: http://oracletoday.blogspot.com/2005/11/bulk-collect_15.html

Yet another option is to have the procedure return a cursor. This is useful in the case where the calling code expects to be able to fetch the data that the procedure has selected:

PROCEDURE GET_MY_REPORT( varReportStartDate in date,  varReportEndDate in date, cur out sys_refcursor) is
begin
   OPEN cur FOR SELECT * 
     FROM CDR.MSRS_E_INADVCH
     WHERE 1=1
     AND ReportStartDate = varReportStartDate 
     AND ReportEndDate = varReportEndDate;
END GET_MY_REPORT;