Using sql update with multiple where conditions

Question

Gerald Blumberg 2016-8-2

0
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https://ww2.mathworks.cn/matlabcentral/answers/298114-using-sql-update-with-multiple-where-conditions

回答： Gerald Blumberg 2016-8-3

Hello,

I am trying to use the update function to update my sql database. Even though I went to the documentation I still have trouble to update a table of the following structure:

Date........ID........Value1........ Value2

--------------------------------------

1.1............1...........5................7

1.1............2...........3................8

...

2.1............1...........9................12

2.1............2...........1............... 333

As you will recognize, "ID" as well as "Date" values occure more than ones and aren't unique. Only the combination of both is unique. Thats why I need multiple whereclause conditions!

Imagine I want to update the column "Value2" in the first 2 rows. How would I do that? I found some solutions using set and case but i want to update some thousends of data thats why hard coding the combination would be pretty uncool...

So far I have a valid connection "conn" and a cell ("cell2insert") which obtains a new value in each row; i.e. cell2insert = {1;2}; Additionally, I have a cell "whereclause" obtaining strings: whereclause = {'where Date = 1.1. and ID = 1' ; 'where Date = 1.1. and ID = 2'};

Using this, I try to apply "update": update(conn, aim , {'Value2'} , cell2insert , whereclause); (where aim is my database table)

I tryed to use a table instead of cell2insert but failed anyway...

Thanks in advance and regards, Gerald