MySQL中嵌套循环中的多个游标

I wish to do something which appear a bit complicated in MySQL. In fact, I wish to open a cursor, do a loop, and in this loop, open a second cursor using the data from the previous fetch to be executed, and re-loop on the results.

我想做一些在MySQL中显得有点复杂的事情。实际上，我希望打开一个游标，执行一个循环，在这个循环中，使用前面将要执行的fetch数据打开第二个游标，并对结果重新循环。

  DECLARE idind INT;
  DECLARE idcrit INT;
  DECLARE idindid INT;
  DECLARE done INT DEFAULT 0;
  DECLARE done2 INT DEFAULT 0;
  DECLARE curIndicateur CURSOR FOR SELECT id_indicateur FROM indicateur;
  DECLARE curCritereIndicateur CURSOR FOR SELECT C.id_critere FROM critere C where C.id_indicateur=idind;
  DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET done = 1;

  set idindid=54;
  OPEN curIndicateur;
  REPEAT
    FETCH curIndicateur INTO idind;
    open curCritereIndicateur;
    REPEAT
      FETCH curIndicateur INTO idcrit;
      INSERT INTO SLA_DEMANDE_STATUS (iddemande,idindicateur,indicateur_status,progression) values('0009',idcrit,'OK',10.0);
    UNTIL done END REPEAT;
    close curCritereIndicateur;
  UNTIL done END REPEAT;
  CLOSE curIndicateur;

In fact, how to do 'Until done' differently for the two cursors, because you can only declare one handler for SQLSTATE? If the first ends, the second ends too.

实际上，对于两个游标，如何做“直到完成”，因为您只能为SQLSTATE声明一个处理程序?如果第一个结束，第二个也结束。

5 个解决方案

#1

You need to define a new BLOCK inside your 1st cursor loop and use different Declares in that block.

您需要在第一个游标循环中定义一个新的块，并在该块中使用不同的声明。

Something like:

喜欢的东西:

BLOCK1: begin
    declare v_col1 int;                     
    declare no_more_rows boolean1 := FALSE;  
    declare cursor1 cursor for              
        select col1
        from   MyTable;
    declare continue handler for not found  
        set no_more_rows1 := TRUE;           
    open cursor1;
    LOOP1: loop
        fetch cursor1
        into  v_col1;
        if no_more_rows1 then
            close cursor1;
            leave LOOP1;
        end if;
        BLOCK2: begin
            declare v_col2 int;
            declare no_more_rows2 boolean := FALSE;
            declare cursor2 cursor for
                select col2
                from   MyOtherTable
                where  ref_id = v_col1;
           declare continue handler for not found
               set no_more_rows2 := TRUE;
            open cursor2;
            LOOP2: loop
                fetch cursor2
                into  v_col2;
                if no_more_rows then
                    close cursor2;
                    leave LOOP2;
                end if;
            end loop LOOP2;
        end BLOCK2;
    end loop LOOP1;
end BLOCK1;

#2

Correct me if I'm wrong, but it looks like what you are trying to do is a bulk insert of records into your "SLA_DEMANDE_STATUS" table. Include every criteria for every indicator found and default it with the values of '0009', 'OK' and 10.0 per each indicator's Criteria ID.

如果我错了，请纠正我，但是看起来您要做的是在“SLA_DEMANDE_STATUS”表中大量插入记录。为每个找到的指标包括每个标准，并默认为“0009”、“OK”和每个指标的标准ID为10.0。

This can all be done in a single SQL-Insert. INSERT INTO ... from a SQL-Select...

这可以在一个SQL-Insert中完成。插入……从一个sql select……

Now, if you want to only include a single "id_indicateur" entry, you can add that to the WHERE clause of the select statement.

现在，如果您只想包含一个“id_indicateur”条目，那么可以将其添加到select语句的WHERE子句中。

Notice that my SQL-Select has forced values to correspond with the columns you want to have populated. They will all be inserted to the destination table by the same name. The nice thing about this, you can just run the SQL-SELECT portion just to see the data you would EXPECT to have inserted... if its incorrect, you can adjust it to fit whatever restrictions you want.

请注意，我的sql选择强制值与您希望填充的列相对应。它们都将以相同的名称插入到目标表。这样做的好处是，您只需运行SQL-SELECT部分，就可以看到您希望插入的数据……如果它是错误的，你可以调整它以适应任何你想要的限制。

insert into SLA_DEMANDE_STATUS 
    ( iddemande,
      idindicateur,
      indicateur_status,
      progression ) 
    SELECT 
         '0009' iddemande,
         c.id_criterere idindicateur,
         'OK' indicateur_status,
         10.0 progression
       FROM 
          indicateur i;
             JOIN critere c
                ON i.id_indicateur = c.id_indicateur

#3

you could use loop,and reset the value of the handle,like this:

您可以使用循环，并重置句柄的值，如下所示:

get_something:loop
  open cur;
  fetch cur into temp_key;
  if no_more_record=1 then
    set no_more_record=0;
    close cur;
    leave get_something;
  else
    //do your job;
  end if;
end loop;

#4

Or redefine the CONTINUE HANDLE:

或重新定义继续句柄:

//...
LOOP1: LOOP
      fetch cursor1
      into  v_col1;
      if no_more_rows1 then
         close cursor1;
         leave LOOP1;
      end if;
//...

      SET no_more_rows1=false;//That's new
END LOOP LOOP1;          

It seems that all select statements inside a loop execute the CONTINUE HANDLE

似乎循环中的所有select语句都执行继续句柄

#5

DECLARE _idp INT;
DECLARE _cant INT;
DECLARE _rec INT;
DECLARE done INT DEFAULT 0;
-- Definición de la consulta
DECLARE primera CURSOR FOR SELECT dp.id_prod, SUM(dp.cantidad) AS cantidad, pp.receta FROM tm_detalle_pedido AS dp INNER JOIN tm_producto_pres AS pp
DECLARE segunda CURSOR FOR SELECT id_ins, cant FROM tm_producto_ingr WHERE id_pres = _idp;

-- Declaración de un manejador de error tipo NOT FOUND
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;

-- Abrimos el primer cursor
OPEN primera;

REPEAT

FETCH primera INTO _idp, _cant, _rec;

IF NOT done THEN

 OPEN segunda;
 block2: BEGIN
     DECLARE doneLangLat INT DEFAULT 0;
     DECLARE _ii INT;
     DECLARE i FLOAT;
     DECLARE _canti FLOAT;
     DECLARE CONTINUE HANDLER FOR NOT FOUND SET doneLangLat = 1;

     REPEAT
     FETCH segunda INTO _ii,_canti;
     IF NOT doneLangLat THEN
        IF _rec = 1 THEN
            SET i = _canti * _cant;
            -- Insertamos
            INSERT INTO tm_inventario (id_ins,id_tipo_ope,id_cv,cant,fecha_r) 
            VALUES (_ii, 2, @id, i, _fecha);
        END IF;
     END IF;
     UNTIL doneLangLat END REPEAT;

  END block2;
  CLOSE segunda;

 END IF;

 UNTIL done END REPEAT;
 CLOSE primera;