I am trying to update my table like this:
Update MyTable
SET value = 1
WHERE game_id = 1,
x =-4,
y = 8
SET value = 2
WHERE game_id = 1,
x =-3,
y = 7
SET value = 3
WHERE game_id = 2,
x = 5,
y = 2
I can do a foreach() but that will send over 50 separate Queries which is very slow.
That's why I want it to be combined into 1 big Query.
( I do use an id for each row but the combination of game_id, x and y is what I use to Identify the row I need. )
The update_batch() function from codeIgniter described here:
Update batch with CodeIgniter
was helpful and almost perfect but it only allows for 1 single where clause, you cannot (as far as I understood and tried) enter an array with multiple where clauses.
I've also checked out this question:
MYSQL UPDATE SET on the Same Column but with multiple WHERE Clauses
But it only allows for multiple row updates containing only a single different WHERE clause and I need multiple WHERE clauses! :)
Anwsers can be in simple SQL or with the use of php (and CodeIgniter) or in a different way. I'd this problem to be solved in any possible way ;)
I can really use the advice/help! =D
give this a try by using CASE
Update MyTable
SET value = CASE
WHEN game_id = 1 AND x = -4 AND y = 8 THEN 1
WHEN game_id = 1 AND x = -3 AND y = 7 THEN 2
WHEN game_id = 2 AND x = 5 AND y = 2 THEN 3
ELSE value
END
WHERE game_ID IN (1,2,3) AND -- the purpose of this WHERE clause
x IN (-4, -3, 5) AND -- is to optimize the query by preventing from
y IN (8,7,2) -- performing full table scan.
Related
I am quite new about queries and I would like to know if there is an easier solution for the query I am working on.
For instance I want to get the data where x is 5,7,9,11,13,15 and 17.
I have a query like below;
SELECT * FROM abc WHERE x = 5 or x = 7 or x = 9 or x = 11 or x = 13 or x = 15 or x = 17;
Is it okay to use this query or are there any other simpler and efficient solution?
EDIT
Does it affect the perfomance when I use x=[5,7,8,11,13,15,17] vs x=[5,11,7,15,8,17,13]
X is the ID of another category for instance.
This is shorter but performs equally
SELECT * FROM abc WHERE x in (5,7,9,11,13,15,17)
But remember if one entry in the in clause is null then it returns FALSE.
My problem is how to loop through a table and extract information from another table.
I have a table - X with 470 records:
A B C
111 12 18
121 21 29
127 37 101
I would like to write the following query:
create or replace view NEW as
For j = 1-3
Select * from Y
where imei = X.A(j) and id > X.B(j) and id < X.C(j)
Apologies, I am a matlab programmer so I have used that syntax above to explain what I want. How can I do this in MySql? I have looked up For Loops but mostly it loops through within the same table. I need to loop through a different table and use those criteria in the where statement of a different table.
To get 3 rows from a table, use LIMIT 3 in a subquery. To get related rows in another table, use JOIN.
CREATE OR REPLACE VIEW new AS
SELECT Y.*
FROM Y
JOIN (SELECT *
FROM X
LIMIT 3) AS X ON Y.ime1 = X.a AND Y.id > X.b AND Y.id < X.c
To make LIMIT 3 produce predictable results, you should have an ORDER BY clause in the subquery. Otherwise, it will select an arbitrary set of 3 rows from X.
Trying to wrap my head around how to do this query - I want to return a list of client records and need to exclude clients if they had only a specific value and no other values.
For example
c# value
1 X
1 Y
2 X
3 Y
I want all the records for clients 1 and 3, since they had a value other than X. I do not want client 2, because that client had ONLY X.
I for example want returned in this case:
1 X
1 Y
3 Y
Of course, I could have lots of other records with other client id's and values, but I want to eliminate only the ones that have a single "X" value and no other values.
Maybe using a sub-query?
Try this:
SELECT client, value FROM myTable where `client` in
(select distinct(client) from myTable where value !='X');
Returns:
Client Value
1 X
1 Y
3 Y
Something like this
SELECT ABB2.*
FROM
mytable AS ABB2
JOIN
(SELECT c
FROM mytable
WHERE value <> "X"
GROUP BY c) AS ABB1 ON ABB1.c = ABB2.c
GROUP BY ABB2.c, ABB2.value
It's faster than using a WHERE clause to identify the sub query results (as in Mike's answer)
This question already has an answer here:
Update multiple rows with multiple 'where' clauses for each individual row
(1 answer)
Closed 9 years ago.
I am trying to update my table like this:
Update MyTable
SET value = 1
WHERE game_id = 1,
x =-4,
y = 8
SET value = 2
WHERE game_id = 1,
x =-3,
y = 7
SET value = 3
WHERE game_id = 2,
x = 5,
y = 2
I can do a foreach() but that will send over 50 separate Queries which is very slow.
That's why I want it to be combined into 1 big Query.
( I do use an id for each row but the combination of game_id, x and y is what I use to Identify the row I need. )
The update_batch() function from codeIgniter described here:
Update batch with CodeIgniter
was helpful and almost perfect but it only allows for 1 single where clause, you cannot (as far as I understood and tried) enter an array with multiple where clauses.
I've also checked out this question:
MYSQL UPDATE SET on the Same Column but with multiple WHERE Clauses
But it only allows for multiple row updates containing only a single different WHERE clause and I need multiple WHERE clauses! :)
Anwsers can be in simple SQL or with the use of php (and CodeIgniter) or in a different way. I'd this problem to be solved in any possible way ;)
I can really use the advice/help! =D
EDIT:
Sorry the question wasn't clear enough, I just changed it!
It seems me you need the logical operator AND:
UPDATE MyTable
SET value = 1
WHERE game_id = 1
AND x = -4
AND y = 8
I'm not familiar with the multiple WHERE clauses how you have it laid out, why not just do
UPDATE MyTable
SET value = 1
WHERE game_id = 1
AND x = -4
AND y = 8
I need to update a MYSQL Table
Here is a very simple look at Table_A
ID VALUE RESULT
1 4 0
2 2 0
3 7 0
I want to update the RESULT Column based on conditions
So my query statement needs to look something like
UPDATE Tabel_A
SET RESULT = (if some condition) 1
OR (if another condition) 2
OR (if a different condition) 3
Or should I use something like
UPDATE Tabel_A
SET RESULT = (CASE 1) 1
(CASE 2) 2
(CASE 3) 3
I am not sure how to structure the query
Thanks
I'll prefer to use CASE here.
UPDATE TAble1
SET Result = CASE value
WHEN 1 THEN x
WHEN 2 THEN y
....
ELSE z
END
or
UPDATE TAble1
SET Result = CASE
WHEN value = 1 THEN x
WHEN value = 2 THEN y
....
ELSE z
END