MySQL IF语句在UPDATE语句的触发器内

Question

我真的希望你能帮我解决这个问题。我试图根据旧字段长度是否大于1来运行两种不同类型的更新查询。这背后的想法是，当用户更新产品时，它会将ProductRef附加到Search表中，该表仅用于搜索。

如此简单，如果ProductRef的字符串长度大于0，请将旧产品ref替换为新产品。否则，添加新产品参考。这是我到目前为止，但它似乎触发了一个错误 -

-- Update the ProductType UpdatedTS that corresponds with this product
-- The below section simply updates the main products UpdatedTS
UPDATE tbl_product_types 
SET UpdatedTS = now() 
WHERE ID = New.ProductTypeID;

IF ( SELECT Length(Old.ProductRef) > 0 )
    BEGIN
        -- We have already stored the product reference so run a replace
        UPDATE tbl_product_type_search AS STable
        SET `STable.Search` = replace(`Search`,CONCAT(Old.ProductRef,' '),New.ProductRef) 
        WHERE `STable.ProductTypeID` = Old.ProductTypeID
    END
ELSE
    BEGIN
        -- We haven't yet stored the product reference, store it
        UPDATE tbl_product_type_search AS STable
        SET `STable.Search` = CONCAT(NEW.ProductRef,' ',`STable.Search`) 
        WHERE STable.ProductTypeID = New.ProductTypeID
    END

供您参考，以下是相关的DB结构：

Answer 1

似乎是UPDATE触发器。不是吗？如果是这样，请尝试此代码（有一些语法错误） -

  UPDATE
    tbl_product_types
  SET
    UpdatedTS = NOW()
  WHERE ID = NEW.ProductTypeID;

  IF (SELECT length(Old.ProductRef) > 0) THEN
    -- We have already stored the product reference so run a replace
    UPDATE
      tbl_product_type_search AS STable
    SET
      `STable.Search` = REPLACE(`Search`, CONCAT(Old.ProductRef, ' '), NEW.ProductRef)
    WHERE
      `STable.ProductTypeID` = OLD.ProductTypeID;
  ELSE
    -- We haven't yet stored the product reference, store it
    UPDATE
      tbl_product_type_search AS STable
    SET
      `STable.Search` = CONCAT(NEW.ProductRef, ' ', `STable.Search`)
    WHERE
      STable.ProductTypeID = NEW.ProductTypeID;
  END IF;

将两个UPDATE语句合并为一个：

UPDATE
  tbl_product_type_search AS STable
SET
  `STable.Search` =
    IF(
      LENGTH(OLD.ProductRef) > 0,
      REPLACE(`Search`, CONCAT(OLD.ProductRef,' '), NEW.ProductRef),
      CONCAT(NEW.ProductRef, ' ', `STable.Search`)
    )
WHERE
  LENGTH(OLD.ProductRef) > 0 AND `STable.ProductTypeID` = OLD.ProductTypeID
  OR
  LENGTH(OLD.ProductRef) <= 0 AND STable.ProductTypeID = NEW.ProductTypeID

关于分隔符：

DELIMITER $$

CREATE TRIGGER trigger_name
AFTER UPDATE
ON table_name
FOR EACH ROW
BEGIN

  UPDATE tbl_product_types...;

  other statements...;
END
$$

DELIMITER ;

Answer 2

以下是未经测试的更新if语句。你可以尝试一下。

UPDATE tbl_product_type_search AS STable 
inner join tbl_product_type_search as Old on STable.ID=Old.ID 
SET `STable.Search` = 
     IF(Length(Old.ProductRef) > 0  AND `STable.ProductTypeID` = Old.ProductTypeID,   
        replace(`Search`,CONCAT(Old.ProductRef,' '),New.ProductRef),  
        IF(Length(Old.ProductRef) < 0 AND STable.ProductTypeID = New.ProductTypeID, 
          CONCAT(NEW.ProductRef,' ',`STable.Search`) ,`STable.Search` ));