Question

I really hope you can help me solve this issue.. I am trying to run two different kinds of update query based on whether the old fields length was greater than one or not. The idea behind this is that when a user updates a product, it will append the ProductRef to the Search table which is used purely for searching.

So simply, if the string length of ProductRef is greater than 0, replace the old product ref with the new one. Otherwise, add the new product ref. Here is what I have so far but it seems to trigger an error –

-- 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

For your reference, here is the relevant DB structure:

Answer 1

It seems that it is UPDATE trigger. Isn’t it? If so, try this code (there were some syntax errors) –

  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;

Two UPDATE statements into one:

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

About delimiters:

DELIMITER $$

CREATE TRIGGER trigger_name
AFTER UPDATE
ON table_name
FOR EACH ROW
BEGIN

  UPDATE tbl_product_types...;

  other statements...;
END
$$

DELIMITER ;