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How can I deactivate a row instead of deleting it, using flag values in MySQL?
Add an active column to the table, and then do:
UPDATE YourTable
SET active = 0
WHERE id = :id
to deactivate the row. You'll then need to update all other queries so they do:
WHERE active = 1
There's no built-in mechanism that does this automatically.
You can create a column in your table as type CHARACTER(1), and use something like 'A' for active and 'D' for deactivated.
There isn't a "flag value" for mysql, people refer to it as a flag, as they created the flag within their own tables for use as such.
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I have millions of data in my database table customer. In that, I have the id_token attribute which has value like cus00001 format now I want to change it to ank00001.
What will be the query in rails or mysql to do it for all the data in the database?
You can use simple update query using REPLACE function:
UPDATE `table_name` SET `id_token` = REPLACE(`id_token`, 'ank', 'cus');
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I have a table named tblMitigation, which has several columns:
Headcode, Time, Origin, Destination, Mitigation, Next Service.
The Next Service column refers to another Headcode value in the same table. How can I use MySQL to look up the Mitigation column for that other service?
Thanks
Chris
You could JOIN the table to itself. Use a LEFT JOIN in case there is no Next Service as yet. The COALESCE will ensure the value of Next_Mitigation is something different in that case e.g. N/A
SELECT current.*, COALESCE(next.Mitigation, 'N/A') AS Next_Mitigation
FROM tblMitigation current
LEFT JOIN tblMitigation next ON next.Headcode = current.`Next Service`
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Is it possible to create a table with value that auto increments every 1 second ? if yes it is appreciated to give a simple example.
Use mysql event with auto_increment column in target table
CREATE EVENT table_insert
ON SCHEDULE EVERY 1 SECOND
DO
UPDATE inc SET value=value+1 where id=1
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Not sure it is possible, but I am trying to import a large set of data and I want to make the cases for certain fields to be imported as all lowercase. I know how to do it once the data is loaded but it takes forever so was looking to do it as I imported it.
Thanks
Create a database trigger which will ensure that all characters are coverted to lowercase before storing in a particular filed
CREATE TRIGGER lc_ins BEFORE INSERT ON tablename FOR EACH ROW
SET NEW.fieldname = LOWER(NEW.fieldname);
CREATE TRIGGER lc_upd BEFORE UPDATE ON tablename FOR EACH ROW
SET NEW.fieldname = LOWER(NEW.fieldname);
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I have on before trigger. Lets say i insert a row. Is it posible to insert another row in the trigger into the same table so there are 2 total rows inserted?
If it is on the same table, the answer is a big NO.
If you want to add another duplicate row, it would cause a circular invocation of BEFORE trigger. Circular operations on the same table are not allowed in a trigger.
You can only add a new row to another table but not in the same table.
Refer to: MySQL: Triggers