更新案例mysql

Question

I'm using Mysql and I'm having a difficult time trying to get the results from a update query. I am having 2 tables. First table loaddata_temp and second table section company_category

first table loaddata_temp

|id_external|company_name               |company_category_id|
-------------------------------------------------------------
|          1|iqballord                  |UD                 |
|          2|A Plus Lawn Care           |PT                 |
|          3|A. L. Price                |PMA                |
|          4|A.J. August Fashion Wear   |BUMN               |
|          5|A+ Electronics             |WARUNG             | 
|          6|A+ Investments             |PT                 | 

second Table Company_category

|company_category_id|company_category_description|
--------------------|-----------------------------
|                  3|PT                          |
|                  5|UD                          |
|                  6|PMA                         |
|                  7|BUMN                        |
|                 23|Koperasi                    |

I used this query to get results as

UPDATE loaddata_temp,company_category
       SET loaddata_temp.company_category_id= 
        CASE 
            WHEN loaddata_temp.company_category_id = company_category.company_category_description 
            THEN company_category.company_category_id
            ELSE 'error' END

what i expeted from above query

|id_external|company_name               |company_category_id|
-------------------------------------------------------------
|          1|iqballord                  |5                  |
|          2|A Plus Lawn Care           |3                  |
|          3|A. L. Price                |6                  |
|          4|A.J. August Fashion Wear   |7                  |
|          5|A+ Electronics             |error              | 
|          6|A+ Investments             |3                  | 

but what i get

|id_external|company_name               |company_category_id|
-------------------------------------------------------------
|          1|iqballord                  |error              |
|          2|A Plus Lawn Care           |error              |
|          3|A. L. Price                |error              |
|          4|A.J. August Fashion Wear   |error              |
|          5|A+ Electronics             |error              | 
|          6|A+ Investments             |3                  |

Answer 1

I would use the following query:

UPDATE      loaddata_temp lt
LEFT JOIN   company_category cc
        ON  cc.company_category_description = lt.company_category_id
    SET     lt.company_category_id = COALESCE(cc.company_category_id, 'error');

Use LEFT JOIN to find matching rows for update. If no row was found in company_category table then update to 'error'.

Answer 2

UPDATE loaddata_temp l LEFT JOIN company_category c ON c.company_category_description = l.company_category_id
       SET loaddata_temp.company_category_id= If(c.company_category_id IS NULL, 'error' ,c.company_category_id)

you can also use IF statement in query if company_category_id found then it will update the same otherwise return 'error'.