SQL update table values from a different table

Question

I have 2 tables xcart_products which has productid , meta_description and many other fields . The 2nd table is xcart_extra_field_values which has ( productid fieldid and value )

I need to copy the value of fieldID = 1 of xcart_extra_field_values

into

the meta_description column of the xcart_products table where the Productid are same.

UPDATE `xcart_products` SET meta_description = ( SELECT value FROM
      xcart_extra_field_values WHERE fieldid = 1 AND
      xcart_extra_field_values.productid = xcart_products.productid ) 
WHERE 
    xcart_extra_field_values.productid = xcart_products.productid ;

I wrote the above SQL but i am getting an error

#1054 - Unknown column 'xcart_extra_field_values.productid' in 'where clause'

Answer 1

I hope this will work for you:

UPDATE `xcart_products`, `xcart_extra_field_values` SET xcart_products.meta_description = xcart_extra_field_values.value 
WHERE
xcart_extra_field_values.fieldid = 1
AND
xcart_products.productid = xcart_extra_field_values.productid

Answer 2

You need to the second table name to your query, because it is used in the query, even though you are not changing any data in it.

UPDATE xcart_products, xcart_extra_field_values

Answer 3

You could use the multiple-table UPDATE syntax to join the tables instead:

UPDATE xcart_products JOIN xcart_extra_field_values USING (productid)
SET    xcart_products.meta_description = xcart_extra_field_values.value
WHERE  xcart_extra_field_values.fieldid = 1;