Create Column in MySql on Insert - mysql

I have devoted a long time of my career on MySQL and recently shifted to MongoDB. On of the very fine feature about MongoDB is that we don't need to alter or create columns on Collection/Table specifically. The column will be created as we insert Data. For e.g., If we have a collection/table named as Emp in MongoDb, I can pass an object to it like:
{
id:12,
name:'abc',
phone:8298999
}
If Emp doesn't has column phone or any other, it will not report an error, rather the missing column will be created automatically on insert, and previous records will hold a default null value for newly created column.
Does such functionality exists in MySQL? To summarize, while Inserting a new record in MySQL table, if a column doesn't exists in table and is mentioned in INSERT query, can that missing column be automatically created with a default value?

Related

Auto increment column in mysql when importing with phpmyadmin

I have a table in mysql with the following headings:
staff_id,dept_id,role_id,username,firstname,lastname,passwd,backend,email,phone,phone_ext,mobile,signature,lang,timezone,locale,notes,isactive,isadmin,isvisible,onvacation,assigned_only,show_assigned_tickets,change_passwd,max_page_size,auto_refresh_rate,default_signature_type,default_paper_size,extra,permissions,created,lastlogin,passwdreset,updated
staff_id is a primary key value and is set to AUTO_INCREMENT.
I found the solution by Queue in this post really helpful, although when the data is being imported the staff_id column is not being auto-incremented. I am inserting the column names in the Format-Specific Options in phpmysql. I can only get it to populate if the staff_id value exists in the csv file I am trying to import.
So if the data looks like this:
2,1,1,agent,Mista,Busta,NULL,NULL,agent#company.org,,NULL,,,NULL,NULL,NULL,<p>this is an agent; mista busta; agent#company.org</p>,1,0,1,0,0,0,0,0,0,none,Letter,"{""def_assn_role"":true}","{""user.create"":1,""user.delete"":1,""user.edit"":1,""user.manage"":1,""user.dir"":1,""org.create"":1,""org.delete"":1,""org.edit"":1,""faq.manage"":1}",2020-02-04 10:18:42,NULL,NULL,2020-02-04 10:18:42
...note the first '2' is the staff_id. What I would like do is have this in the csv:
,1,1,agent,Mista,Busta,NULL,NULL,agent#company.org,,NULL,,,NULL,NULL,NULL,<p>this is an agent; mista busta; agent#company.org</p>,1,0,1,0,0,0,0,0,0,none,Letter,"{""def_assn_role"":true}","{""user.create"":1,""user.delete"":1,""user.edit"":1,""user.manage"":1,""user.dir"":1,""org.create"":1,""org.delete"":1,""org.edit"":1,""faq.manage"":1}",2020-02-04 10:18:42,NULL,NULL,2020-02-04 10:18:42
...leaving the staff_id column blank and allowing mysql to auto-populate (auto_increment) as it sees fit.
AUTO INCREMENT is set at the server level within MySQL, and can be overwritten if assigned manually within a CSV or other import. If you simply exclude the entire column from your import, you'll allow MySQL to do what is set as default for that column, and automatically assign ID's, since it doesn't think you want to assign them yourself.
Also as a side note, if you import more than once without using TRUNCATE TABLE -- MySQL will pick up on the last inserted ID and move on from there, even if the table is empty. So if you ever want to start over from 1 you'll have to trucate the table.

Insert into table with auto-increment field

I have two tables called HRData and HRDataHistory. HRDataHistory has the same structure as HRData except the first column is an autoincrement field and the last column is a DateTime field.
HRData has a trigger:
CREATE TRIGGER [HR].[HRData_History]
ON [HR].[HRData]
AFTER INSERT, UPDATE
AS
INSERT INTO HR.HRDataHistory
SELECT *, GETDATE()
FROM inserted
;
GO
This is working on an existing development machine. I am trying to mirror this relationship on my local sql server instance so that I can test some changes. Using SSMS I used 'Script Table as Create To...' and created the structure of each table and index on my local sql server instance. However when I do this for the trigger I get the following error:
An explicit value for the identity column in table 'HR.HRDataHistory' can only be specified when a column list is used and IDENTITY_INSERT is ON.
I know the preferred method would be to specify the columns, but I want to mirror production which does not currently do that and further I want to understand why it is working in production but not on my test database.
You're getting this error because you're trying to insert data into an IDENTITY column, which auto-populates itself whenever you insert another row in that table.
Off the top of my head, you can do something like below (although I believe there are more elegant solutions and I do not guarantee that this is a safe solution, nor have I tried something like this and I recommend testing on a TEST database before trying in production/LIVE):
add another column to HRDataHistory table which does not have identity set on it (because you cannot remove identity form a colum once set), but must have the same datatype as the current ID (IDENTITY) column
use a UPDATE query to move all of your ID's from your IDENTITY column to your new column:
UPDATE HRDataHistory
SET new_column = ID
Drop the IDENTITY column (but this might have grave implications if you have any FK set on it and possibly other objects that use it):
ALTER TABLE HRDataHistory
DROP COLUMN ID
Rename the "new_column" to the name of your previous IDENTITY column:
EXEC sp_RENAME 'HRDataHistory.new_column' , 'ID', 'COLUMN'
At this point I believe you can use your trigger to "copy" the newly inserted data from the HRData table into the HRDataHistory, since the column names should match and there is no more conflict due to IDENTITY.
Again, this might (not guaranteed) work so I recommend you first check on a TEST environment.

how to update the value of one table when the value is inserted in another table using mysql?

hi i have two tables namely
sms(Message,sms_index...columns)
c_paid_bribe(c_addi_info,....)
what i want to do is to insert the values of Message column of sms table into c_addi_info column of c_paid_bribe table automatically whenever a new value is inserted into sms table.
I tried this
$query=mysql_query("insert into bd_paid_bribe(c_addi_info) select Message from sms");
But when a new value is inserted and i run the .php file the already existed values are also inserting into the table again.....
Q: what i want to do is to insert the values of Message column of sms table into c_addi_info column of c_paid_bribe table automatically whenever a new value is inserted into sms table.
A: If you want to update one table when another is changed (and, for whatever reason, you can't simply do this in your application), then use "triggers":
http://net.tutsplus.com/tutorials/databases/introduction-to-mysql-triggers/
Q: But when a new value is inserted and i run the .php file the already existed values are also inserting into the table again.....
A: You want an "upsert". For example:
How do I update if exists, insert if not (AKA "upsert" or "merge") in MySQL?
What you want to do is simply to make two queries that are comitted in one transaction. This is what transactions are for. See here for examples on how to do it:
PHP + MySQL transactions examples

Mysql triggers : OLD and NEW as a string/xml/parameter?

I would like to store all changes to my tables (in MySQL). I created a table 'audit' to track all changes of all tables in one table (so I don't have to create audit-tables for each table).
I then created triggers for each table and a stored procedure that inserts a record into the audit-table. The parameters for the stored procedure are the tablename and the primary id. Now I'm able to track the insert/update/delete dates for each record in my database.
But I also would like to trace all changes to the DATA with this procedure. For this I'd have to find a way to use the OLD and NEW records from the triggers in the stored procedure.
Anybody know how to do this?
Maybe some kind of serializing the records OLD and NEW into a string??
The only solution that I could derive was checking the OLD & NEW values of every field in my table.
BEGIN
-- record changes to table log_new
IF OLD.fieldA != NEW.fieldA
OR OLD.fieldB != NEW.fieldB
THEN
INSERT INTO log_new (

Adding a time dimension to MySQL cells

Is there a way to keep a timestamped record of every change to every column of every row in a MySQL table? This way I would never lose any data and keep a history of the transitions. Row deletion could be just setting a "deleted" column to true, but would be recoverable.
I was looking at HyperTable, an open source implementation of Google's BigTable, and this feature really wet my mouth. It would be great if could have it in MySQL, because my apps don't handle the huge amount of data that would justify deploying HyperTable. More details about how this works can be seen here.
Is there any configuration, plugin, fork or whatever that would add just this one functionality to MySQL?
I've implemented this in the past in a php model similar to what chaos described.
If you're using mysql 5, you could also accomplish this with a stored procedure that hooks into the on update and on delete events of your table.
http://dev.mysql.com/doc/refman/5.0/en/stored-routines.html
I do this in a custom framework. Each table definition also generates a Log table related many-to-one with the main table, and when the framework does any update to a row in the main table, it inserts the current state of the row into the Log table. So I have a full audit trail on the state of the table. (I have time records because all my tables have LoggedAt columns.)
No plugin, I'm afraid, more a method of doing things that needs to be baked into your whole database interaction methodology.
Create a table that stores the following info...
CREATE TABLE MyData (
ID INT IDENTITY,
DataID INT )
CREATE TABLE Data (
ID INT IDENTITY,
MyID INT,
Name VARCHAR(50),
Timestamp DATETIME DEFAULT CURRENT_TIMESTAMP)
Now create a sproc that does this...
INSERT Data (MyID, Name)
VALUES(#MyID,#Name)
UPDATE MyData SET DataID = ##IDENTITY
WHERE ID = #MyID
In general, the MyData table is just a key table. You then point it to the record in the Data table that is the most current. Whenever you need to change data, you simply call the sproc which Inserts the new data into the Data table, then updates the MyData to point to the most recent record. All if the other tables in the system would key themselves off of the MyData.ID for foreign key purposes.
This arrangement sidesteps the need for a second log table(and keeping them in sync when the schema changes), but at the cost of an extra join and some overhead when creating new records.
Do you need it to remain queryable, or will this just be for recovering from bad edits? If the latter, you could just set up a cron job to back up the actual files where MySQL stores the data and send it to a version control server.