MySQL update table with data from another table based on field - mysql

Question

I have a database that looks like this
leads
name zip city county state
Bill 84058
Susan 90001
FullUSZipCodes
ZipCode City County State
84058 Orem Utah Utah
90001 Los Angeles South California
As you can see, in the leads database the city, count and state are empty, i'm trying to merge the data so that the first table would look like this:
leads
name zip city county state
Bill 84058 Orem Utah Utah
Susan 90001 Los Angeles South California
This is the first query I tried:
UPDATE leads SET leads.county = FullUSZipCodes.County WHERE leads.zip = FullUSZipCodes.ZipCode
which didn't work, and here is the 2nd query:
UPDATE leads INNER JOIN FullUSZipCodes ON leads.zip = FullUSZipCodes.ZipCode SET leads.county = FullUSZipCodes.County, leads.city = FullUSZipCodes.City, leads.state = FullUSZipCodes.State

Answer 1

Your second query looks like it should work, but I would write it slightly differently:
UPDATE leads t1
INNER JOIN FullUSZipCodes t2
ON t1.zip = t2.ZipCode
SET
t1.city = t2.City,
t1.county = t2.County,
t1.state = t2.State
WHERE
t1.city IS NULL OR t1.county IS NULL OR t1.state IS NULL;
If the leads table has a lot of records, and performance is a concern, you can try adding a WHERE clause to the update query which targets only those records which are missing one or more pieces of address information. I think there is nothing wrong with always updating all three columns together, because typically this information tends to be grouped together.