WHILE LOOP with IF STATEMENT MYSQL

问题

I would like to create a stored routine for MySQL that figures out the number of business or working days for a month (Working Days are Monday thru Friday).

It's a syntax error however I don't know what the syntax error is. All it tells me is:

1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'WHILE(@daycount < @totaldays) DO IF (WEEKDAY(@checkweekday) < 6) THEN ' at line 2

My Syntax Error is in the following:

    WHILE(@daycount < @totaldays) DO
          IF (WEEKDAY(@checkweekday) < 6) THEN

My Code:

      SELECT MONTH(CURDATE()) INTO @curmonth;
      SELECT MONTHNAME(CURDATE()) INTO @curmonthname;
      SELECT DAY(LAST_DAY(CURDATE())) INTO @totaldays;
      SELECT FIRST_DAY(CURDATE()) INTO @checkweekday;
      SELECT DAY(@checkweekday) INTO @checkday;
      SET @daycount = 0;
      SET @workdays = 0;

    BEGIN
      WHILE(@daycount < @totaldays) DO
          IF (WEEKDAY(@checkweekday) < 6) THEN
            SET @workdays = @workdays+1;
          END IF;
          SET @daycount = @daycount+1;
          SELECT ADDDATE('@checkweekday', INTERVAL 1 DAY) INTO @checkweekday;
      END WHILE;
    END;
    SELECT @workdays;

Is someone able to assist?

UPDATE I receive the same error with the following bit of code so it probably has something to do with this:

    SET @workdays = 0;
    IF (WEEKDAY('2013-06-13') < 6) THEN
      SET @workdays = @workdays+1;
    END IF;
    SELECT @workdays;

回答1:

I have discovered that you cannot have conditionals outside of the stored procedure in mysql. This is why the syntax error. As soon as I put the code that I needed between

   BEGIN
   SELECT MONTH(CURDATE()) INTO @curmonth;
   SELECT MONTHNAME(CURDATE()) INTO @curmonthname;
   SELECT DAY(LAST_DAY(CURDATE())) INTO @totaldays;
   SELECT FIRST_DAY(CURDATE()) INTO @checkweekday;
   SELECT DAY(@checkweekday) INTO @checkday;
   SET @daycount = 0;
   SET @workdays = 0;

     WHILE(@daycount < @totaldays) DO
       IF (WEEKDAY(@checkweekday) < 5) THEN
         SET @workdays = @workdays+1;
       END IF;
       SET @daycount = @daycount+1;
       SELECT ADDDATE(@checkweekday, INTERVAL 1 DAY) INTO @checkweekday;
     END WHILE;
   END

Just for others:

If you are not sure how to create a routine in phpmyadmin you can put this in the SQL query

    delimiter ;;
    drop procedure if exists test2;;
    create procedure test2()
    begin
    select ‘Hello World’;
    end
    ;;

Run the query. This will create a stored procedure or stored routine named test2. Now go to the routines tab and edit the stored procedure to be what you want. I also suggest reading http://net.tutsplus.com/tutorials/an-introduction-to-stored-procedures/ if you are beginning with stored procedures.

The first_day function you need is: How to get first day of every corresponding month in mysql?

Showing the Procedure is working Simply add the following line below END WHILE and above END

    SELECT @curmonth,@curmonthname,@totaldays,@daycount,@workdays,@checkweekday,@checkday;

Then use the following code in the SQL Query Window.

    call test2 /* or whatever you changed the name of the stored procedure to */

NOTE: If you use this please keep in mind that this code does not take in to account nationally observed holidays (or any holidays for that matter).

来源：https://stackoverflow.com/questions/17139074/while-loop-with-if-statement-mysql

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mysql

do-while