Updating multiple rows 100 local wife dating
I was not able, using my SQL 4.1.1, to do this as a subquery: UPDATE Groups LEFT JOIN (SELECT Group Id, MIN(Val Within Group) AS base Val FROM Groups GROUP BY Group Id) AS Grp Sum USING (Group Id) SET Val Within Group=Val Within Group-base Val; Csaba Gabor UPDATE Syntax with "on-line" updating value limitations.
I had a problem - a had to update a column "rate" but if the existince or new value is greater then 5 this "5" will be finally value in field.
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Here is a way to use multiple tables in your UPDATE statement, but actually copying one row values into the other, meaning, we're using the same table: UPDATE jobs AS to Table, jobs AS from Table SET to Table.job_type_id = from Table.job_type_id, to Table.job_company_id = from Table.job_company_id, to Table.job_source = from Table.job_source, WHERE (to Table.job_id = 6) AND (from Table.job_id = 1)--------------Pretty cool.
What I'm doing here is copying the information I need from the row where job_id=1 to the row where job_id=6, on the same table.
Adam Boyle's commment above was just what I was trying to do, update one table based on a relationship between that table and another.
If you want to return the value before you updated it without using a seperate select (which unless you lock the table could return a different value than is updated) then you can use a mysql variable like this:update some_table set col = col 1 where key = 'some_key_value' and @value := col The @value := col will always evaluate to true and will store the col value before the update in the @value variable. Additional information on My SQL correlated subqueries is at UPDATE can apparently be used to implement a semaphore (pardon my pseudocode):while TRUE The code above waits until the semaphore is "cleared" (value = 0) and then "sets" it (value = 1).
You could then do select @value;in order to see what the value was before you updated it My SQL uses Watcom (Oracle) syntax for UPDATE, so it's possible to write something like:update Table1 t1 join Table2 t2 on t1. When done, you "clear" the semaphore by UPDATE table SET value = 0 WHERE name = 'name' The assumption is that the UPDATE is "atomic" in that no concurrent access by another process can occur between testing and setting the value field.
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So, I do it in one "magick" query ;)Here an example:"3" is a some value, from form or somethingupdate item set rate = case when round((rate 3)/2) You sometimes run into the problem that you want to replace a substring occuring in a column with a different string, without touching the rest of the string.