I am trying to understand how to UPDATE multiple rows with different values and I just don't get it. The solution is everywhere but to me it looks difficult to understand.
For instance, three updates into 1 query:
UPDATE table_users
SET cod_user = '622057'
, date = '12082014'
WHERE user_rol = 'student'
AND cod_office = '17389551';
UPDATE table_users
SET cod_user = '2913659'
, date = '12082014'
WHERE user_rol = 'assistant'
AND cod_office = '17389551';
UPDATE table_users
SET cod_user = '6160230'
, date = '12082014'
WHERE user_rol = 'admin'
AND cod_office = '17389551';
I read an example, but I really don't understand how to make the query. i.e:
UPDATE table_to_update
SET cod_user= IF(cod_office = '17389551','622057','2913659','6160230')
,date = IF(cod_office = '17389551','12082014')
WHERE ?? IN (??) ;
I'm not entirely clear how to do the query if there are multiple condition in the WHERE and in the IF condition..any ideas?
This question is related to
mysql
sql
sql-update
UPDATE Table1 SET col1= col2 FROM (SELECT col2, col3 FROM Table2) as newTbl WHERE col4= col3
Here col4 & col1 are in Table1. col2 & col3 are in Table2
I Am trying to update each col1 where col4 = col3 different value for each row
MySQL allows a more readable way to combine multiple updates into a single query. This seems to better fit the scenario you describe, is much easier to read, and avoids those difficult-to-untangle multiple conditions.
INSERT INTO table_users (cod_user, date, user_rol, cod_office)
VALUES
('622057', '12082014', 'student', '17389551'),
('2913659', '12082014', 'assistant','17389551'),
('6160230', '12082014', 'admin', '17389551')
ON DUPLICATE KEY UPDATE
cod_user=VALUES(cod_user), date=VALUES(date)
This assumes that the user_rol, cod_office
combination is a primary key. If only one of these is the primary key, then add the other field to the UPDATE list.
If neither of them is a primary key (that seems unlikely) then this approach will always create new records - probably not what is wanted.
However, this approach makes prepared statements easier to build and more concise.
I did it this way:
<update id="updateSettings" parameterType="PushSettings">
<foreach collection="settings" item="setting">
UPDATE push_setting SET status = #{setting.status}
WHERE type = #{setting.type} AND user_id = #{userId};
</foreach>
</update>
where PushSettings is
public class PushSettings {
private List<PushSetting> settings;
private String userId;
}
it works fine
You can use a CASE
statement to handle multiple if/then scenarios:
UPDATE table_to_update
SET cod_user= CASE WHEN user_rol = 'student' THEN '622057'
WHEN user_rol = 'assistant' THEN '2913659'
WHEN user_rol = 'admin' THEN '6160230'
END
,date = '12082014'
WHERE user_rol IN ('student','assistant','admin')
AND cod_office = '17389551';
To Extend on @Trevedhek answer,
In case the update has to be done with non-unique keys, 4 queries will be need
NOTE: This is not transaction-safe
This can be done using a temp table.
Step 1: Create a temp table keys and the columns you want to update
CREATE TEMPORARY TABLE temp_table_users
(
cod_user varchar(50)
, date varchar(50)
, user_rol varchar(50)
, cod_office varchar(50)
) ENGINE=MEMORY
Step 2: Insert the values into the temp table
Step 3: Update the original table
UPDATE table_users t1
JOIN temp_table_users tt1 using(user_rol,cod_office)
SET
t1.cod_office = tt1.cod_office
t1.date = tt1.date
Step 4: Drop the temp table
update table_name
set cod_user =
CASE
WHEN user_rol = 'student' THEN '622057'
WHEN user_rol = 'assistant' THEN '2913659'
WHEN user_rol = 'admin' THEN '6160230'?
END,date = '12082014'
WHERE user_rol IN ('student','assistant','admin')
AND cod_office = '17389551';
Source: Stackoverflow.com