php - MySQLi- How to get number of records in one table that do not match values in another table -

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• how find missing value between 2 mysql tables 4 answers

sorry obscure title... don't know how best explain this.

i have 2 tables, valid_sizes , items

valid_sizes:

id    sizeid    description 1     40        small 2     41        medium 3     42        large 

items:

id    size 1     41 2     41 3     40 4     99 5     42 6     98 

i attempting perform query finds how many items exist size not exist in valid_sizes table. in instance, query return 2. (items 4 , 6 not exist sizeid)

how done?

something should work. want left join, , check null results.

   select * items     left join valid_sizes on items.sizeid = valid_sizes.size          size null;