无法使用来自另一个的相应数据正确更新一个MYSQL表

Question

Currently, my task is to update the Place1 column in my mkindex table, with the corresponding mkplace_id value in the mkplace table. This seemed simple enough, but I must be misunderstanding something or missing some detail.

The desired result would be storing the corresponding mkplace_id in place of mkindex.Place1

I began by trying variations on this:

UPDATE mkindex INNER JOIN mkplace ON mkindex.Place1 = mkplace.mkplace_name SET mkindex.Place1 = mkplace.mkplace_id

This does not have the effect I want it to have. The inner join itself actually matches some of the Place1 = mkplace_name , but absolutely not all expected matches. It returns some 117 matches, out of the hundreds of thousands that it should return, and furthermore it doesn't actually set any rows with mkindex.Place1 to mkplace.mkplace_name .

This led me to try a few other methods, including:

UPDATE mkindex SET mkindex.Place1 = ( SELECT mkplace_id FROM mkplace WHERE mkindex.Place1 = mkplace.mkplace_name LIMIT 1 )

The number of matches seem to be around the right number, but it just replaces every instance of Place1 with NULL.

Am I overlooking something obvious? I also considered it being due to collation, so I have also tried running this before the query:

ALTER TABLE mkplace CONVERT TO CHARACTER SET latin1 COLLATE latin1_general_ci

Any guidance would be greatly appreciated, I'm more confused than anything at this point.

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mkindex (latin1_general_ci)

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mkplace (utf8_general_ci)

Answer 1

Your first query looks fine, I'm going to go out on a limb and suggest that there may only be 117 rows where mkindex.Place1 is actually equal to mkplace.mkplace_name. Machines don't lie. You could add a TRIM() around each column but I doubt that will help. To get an idea what you're dealing with try analyzing mkindex first.

 SELECT mkindex.Place1, COUNT(*) FROM mkindex GROUP BY mkindex.Place1;