I have got two tables. I want to update MODEL in table2 when ITEM in table1 equals ITEM in table2.
Any Ideas?
In MySQL, you do it like this
UPDATE table1 t1
INNER JOIN table2 t2
ON t1.id = t2.id
SET t1.col1 = t2.col1,
t1.col2 = t2.col2
If I understand correctly, you just want to perform an UPDATE on table2 based on, presumably, foreign keys?
If that's right, this should work:
UPDATE
table2
JOIN table1
ON table1.ITEM = table2.ITEM
SET
MODEL = 'new value';
The table declaration in an UPDATE statement is the same as is specified in a SELECT statement - so you can use any type of JOIN that fits your table/data.
Docs for UPDATE, SELECT.
If you could add an actual query attempt, or something, that might be helpful. Can you try something like the following:
UPDATE table2 JOIN table1 ON table2.ITEM = table1.ITEM SET MODEL = ?
Related
I need to update a table with values coming from another table while statisfying a few conditions in the meantime.
To be more specific, the 'source' field of table1 needs to get updated by the field 'value' from table2.
These 2 tables share a common 'id' field that can be used for a join. If the 'id' of table1 doesn't have any correspondence in table2, then it should take the value of the 'source2' field from table3. If the 'source2' value is 'NULL', then it should be given a default value that we will name 'Default' in this example.
As an example, we have the table1 below, which is the one we want to update:
Then we have the table2 below, which is the source table that will be used to update table1:
Finally we have table3, which will be used if the information in table2 is unavailable:
Based on this example, I would like to write a query that would update table1 with the values below:
I have written the following query using MariaDB but obviously it is not correct:
UPDATE table1 T1
LEFT JOIN table2 T2 ON T1.id = T2.id
LEFT JOIN table3 a ON T1.id = T3.id
SET T1.source = if(T2.value is NULL, if(T3.source is NULL, 'Default', T3.source), T2.value)
WHERE T1.id = T2.id
Which parts should be amended to make it work?
You seem quite close. The left join logic is fine, we just need to adjust the conditional set and the where clause:
update table1 t1
left join table2 t2 on t2.id = t1.id
left join table3 t3 on t3.id = t1.id
set t1.source = coalesce(t2.value, t3.source, 'Default')
where t2.id is not null or t3.id is not null
coalesce() returns its first non-null argument.
The where clause ensures that we don't update rows that match in neither tables. You can remove it if you want to update all rows (those that do not match will get 'Default' assigned).
Hi I have two table one like this one:
table1
and one like this:
table2
I would like to update all the fields on the table2 column "newID" based on this rules: if (table2.ID = table1.ID_actual or table2.ID=table1.ID_old) then table2.newID = table1.newID
How can I resolve this problem ?
You need a join of the 2 tables in the UPDATE statement:
UPDATE table2 t2
INNER JOIN table1 t1 ON t2.ID IN (t1.ID_actual, t1.ID_old)
SET t2.newID = t1.newID
I have a pretty simple MySQL query to implement, but I can't figure out how...
I have two tables, T1 and T2.
What I need to do:
From T1, I retrieve an ID based on a CODE value:
SELECT id FROM T1 WHERE code = '$code';
Then I need to use this ID (so the value I just retrieved) to update a specific row in T2 (the name of the row will match the ID's value).
I was thinking about using either subqueries or user-defined variables, but no matter how I try it I can't get it done.
If you have any code snippet that can help me doing that, I would appreciate it as well!
EDIT
Just to clarify something: I don't know the name of the column that I need to update in T2, since that name will be the value I retrieve from T1.
So for example, if the ID I get from T1 is "03", it will update the column named "03" in T2.
EDIT 2
Here's a little schema of what I intend to achieve (hoping I make myself clearer, I'm sorry for the misunderstanding...)
UPDATE T2 SET COL = YOUR_VALUE
WHERE T2.ID = (SELECT id FROM T1 WHERE code = '$code')
UPDATE: If the sub query returns more than one row then you can use from IN operator
UPDATE T2 SET COL = YOUR_VALUE
WHERE T2.ID IN (SELECT id FROM T1 WHERE code = '$code')
Use an UPDATE with a JOIN:
UPDATE T2
CROSS JOIN T1
SET T2.`0` = IF(T1.id = 0, T1.someColumn, T2.`0`),
T2.`1` = IF(T1.id = 1, T1.someColumn, T2.`1`),
T2.`2` = IF(T1.id = 1, T1.someColumn, T2.`1`)
WHERE T1.code = '$code'
Replace someColumn with the column in T1 containing the value you want to put into T2.
you can update without using the subquery just using join
update t2
inner join t1 on t2.name = t1.id and t1.code ='$code'
set t2.my_col = 'my_value'
but you should not use var in your query you are at risk for sql injection take a look at you mysql driver for param_binding
UPDATE T2 SET COL = YOUR_VALUE WHERE EXISTS
(SELECT 1 FROM T1 WHERE T2.id=T2.id AND code = '$code')
You can update T2 with the next SQL if you expect at least one row from the inner query
UPDATE T2 SET COLUMN = VALUE
WHERE T2.ID IN (SELECT ID FROM T1 WHERE CODE = $code)
Otherwise, if from T1 you are sure you will get only 1 record
UPDATE T2 SET COLUMN = VALUE
WHERE T2.ID = (SELECT ID FROM T1 WHERE CODE = $code)
update table1 t1
inner join
table2 t2 on
t1.a = t2.a
set t1.b = t2.b,
t1.c = t2.c;
This code works to join 2 tables on column a. My problem is that I have about 500 columns which I want to update and am currently writing out each of the 500 columns in the code up to
t1.500 = t2.500;
This works, but it is slow and inefficient. Does anyone know how you can select * from table2 to update table1, keeping the join on t1.a = t2.a? All of the column names match exactly and am inserting all of the columns from table2. Was thinking of something like this below although I know that this is not correct. Thank you!
update table1 t1
inner join
table2 t2 on
t1.a = t2.a
set t1.* = t2.*;
I think there is no way to make update query with a wildcard in mysql. Don't know if it will properly fit to your problem, but you can try this workaround. :
DELETE FROM table2 WHERE id IN (<ids>);
Delete all the records from table2 that are satisfying given condition. And then insert the corresponding records from table1 to table2.
INSERT INTO table2
SELECT * FROM table1 WHERE id IN (<ids>);
In my mysql I am having t1, t2 tables and I want to update t1's field from t2's field value based on t1's field value match t2's field value
I tried the below but it is not updating. What I did wrongly here
UPDATE t1
INNER JOIN t2
ON t1.name = t2.name
SET t1.age = t2.age
WHERE t1.name IS NOT NULL;
You need to separate the table you want to update from the table your querying, even though it is the same:
UPDATE t1
SET t1.age = t2.age
FROM t1 as tempT1
INNER JOIN t2
ON tempT1.name = t2.name
WHERE tempT1.name IS NOT NULL;
UPDATE
Apparently MySQL is using a different UPDATE JOIN Syntax than other db's. Your initial query seems to use the correct syntax, just to be sure try to alias the table names:
UPDATE t1 temp1
INNER JOIN t2 temp2
ON temp1.name = temp2.name
SET temp1.age = temp2.age
WHERE temp1.name IS NOT NULL;
UPDATE 2
After looking at this a bit longer I'm certain that the WHERE clause is the issue:
WHERE temp1.name IS NOT NULL
You cannot join on null values anyway, so they are filtered out by default. The WHERE clause is somehow interfering with the join.
Try and remove it to see if the UPDATEworks. If you don' t want to execute and update right away simply execute a select with the same JOIN CLAUSE to see which records would be affected.
Here is a general reference to NULL and JOIN:
http://databases.about.com/library/weekly/aa051203a.htm
Here is the SQL Server Reference in compliance with the above: http://msdn.microsoft.com/en-us/library/ms190409.aspx
Could not find a MySQL reference that states this explicitly but I think this is true for all Relational DBs.
I myself also found another way to achieve this same scenario. I am pasting the answer here so that others will get benefit.
UPDATE t1 SET t2_age = (SELECT age FROM t2 BINARY WHERE name = t1.name);
Try this:
update t1
set t1.age = t2.age
from t1
inner join t2 on t1.name = t2.name
where t1.name is not null
Try this
UPDATE t1,t2
SET t1.age = t2.age
FROM t1 as tempT1
INNER JOIN t2 ON tempT1.name = t2.name
WHERE tempT1.name IS NOT NULL;