I have basic knowledge of MS SQL which actually sabotages me as the syntax differs from MySQL in which I need the code written.
I have X databases named "project_%". It's 1 database per project. I need a script or a procedure (it's gonna be rarely used by support) that's gonna take some user info from master DB and add a list of users (or at least a single user) into all (later a list might be required) "project_%" databases.
My idea was to create a variable/temp table to fill with the list of databases and run a cycle (for/while) to set a default schema and insert required data. This is where I'm stuck as I have no idea how to set default schema from a variable or to input the variable into variable_db.table.
What I've found so far always differed from what I needed and couldn't apply it to my code.
Thanks,
Z
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Failed Run
You should first define what is your default Schema or Database so that your query will know where it should place the table.
in MYSQL Workspace, Double Clicking the Schema will automatically sets it up as default and ready to go.
Im trying to run this query to mask the contents in the column "audio" but keep getting the error message for wrong syntax
ALTER TABLE test
ALTER COLUMN audio varchar(10) MASKED WITH (FUNCTION = 'default()');
Where am i going wrong here. Pls help
MySQL does not support MASKED WITH syntax for Dynamic Data Masking. That's a proprietary feature of Microsoft SQL Server.
Microsoft SQL Server is a different RDBMS product from MySQL. Both of these products have features and syntax not supported by the other.
In MySQL 5.7, the DEFAULT can be a constant scalar value, or NULL, or CURRENT_TIMESTAMP. Those are the only options (see https://dev.mysql.com/doc/refman/5.7/en/data-type-defaults.html).
In MySQL 8.0, you can now use a constant expression for the default of a column (see https://dev.mysql.com/doc/refman/8.0/en/data-type-defaults.html).
In both versions, you must use the DEFAULT keyword.
Re your comment:
is there any other way, I can hide this column data for other users other than the root user
You can define a VIEW that excludes columns you want to hide. The view can read the base table, but it does not select the audio column. Users can read the view, but do not grant access to the base table to all users.
MySQL supports granting column-level privileges, but I have never seen anyone use them, and I don't know if they really work.
I have postponed writing SQL code for university, and now that I want to start learning it, I have no idea how to.
In C I'd define headers and begin with coding main, but in SQL classes all I have is a plain example
CREATE TABLE Sailors(
sid INTEGER,
sname VARCHAR(30) NOT NULL,
rating INTEGER DEFAULT 0,
age REAL DEFAULT 18
)
and some commands for using the table I created.
My questions are: How is a correct script supposed to look? How do I run it to create a database? (MySQL) How do I use MySQL to run scripts and where do I type commands in real time to do stuff I haven't scripted?
I just can't wrap my head around it. All tutorials I've seen use a terminal I can't find, or another I did find and I can't use because I get errors using any command (can't create file in some directory and some modules report errors so it shuts down)
The following is a very vague description of Mysql to get an idea of it:
Mysql (or SQL) is separated in 3 types of language:
DML : Data Manipulation Language
DDL : Data Definition Language
DCL : Data Control Language
Read about them to find out which kind of command belongs where.
You will find out that you almost exclusively need DML and DDL to work with Data in MySQL. While DCL is mostly used to keep the database running, control user privileges , etc.
Also when running code there will be only one command of your script executed at a time without a possibility to point somewhere else in your script.
Loops and Cursors can be used , but have to be stored in a special form of script called stored procedure. Usually you execute your code in a sequence without a code based relation between the different commands (the relation comes from the context of the commands).
Get Data into your Database:
(Consider installing the community edition for MySQL if you have problems running MySQL correctly)
To get Data into your Database , you should import data from files into your database. The MySQL-GUIs available (Workbench, Toad, Navicat, HeidSQL...) usually provide an Import Wizard that makes it easy to import Data from all kind of Files (txt, Excel, Database Files ..).
You can create an excel spreadsheet and import it into your database for example.
here is a picture of the Workbench SQL Editor:
https://dev.mysql.com/doc/workbench/en/images/wb-getting-started-tutorial-adding-data-movies.png
Workbench (or any other GUI) will be your IDE. Getting into it will answer many of your questions.
Regarding the correct script:
A complete MySQL command is called a query.
A Query is defined by a ; at the end (default) .
A chain of MySQL commands is called a script.
Therefore, a correct script consists of correct querys.
To solve more complex problems, use stored procedures in MySQL (this should come close to your usage of the word script).
some MYSQL commands you will have to be familiar with:
select
update
insert into
delete
create table
drop table
alter table
You have a lot to read. But make sure that your Database is running and you have some data in it to test code. As you already have programming experience, you should understand this really fast with the right setup.
I am using MS Access 2003 under Windows 7 (64bit), with external linked table at MySQL server (5.0.51a-24+lenny5), connected via MySQL ODBC connector (using 5.1.10, because the newest 5.1.11 is buggy). When I open this table in MS Access and try to delete some records from it, I get following error:
The Microsoft Jet engine stopped the process because you and another
user are attempting to change the same data at the same time.
When I try to edit some records in the table, I get following error:
This record has been changed by another user since you started editing
it. If you save the record, you will overwrite the changes the other
user made.
Copying the changes to the clipboard will let you look at the values
the other user entered, and then paste your changes back in if you
decide to make changes.
However, when I do it via deletion or update query in MS Access, it works fine! I just cannot delete the records directly from the table.
I found out (see the detailed analysis below), that the problem is present when there are double fields with values with a lot of decimal digits. See:
CREATE TABLE `_try4` (
`a` int(11) NOT NULL default '0',
`b` double default NULL,
PRIMARY KEY (`a`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_czech_ci;
insert into _try4 values (1, NULL),(2, 4.532423),(3,10),(4,0),
(5,6.34324),(6, 8.2342398423094823);
The problem is only present when you try to delete/edit the last record (a = 6), otherwise it is OK!
The issue is documented:
http://support.microsoft.com/kb/280730 , proposing these 3 workarounds:
Add a timestamp column to the SQL table. (JET will then use only this field to see if the record has been updated.)
Modify the data type that is in SQL Server to a non-floating point data type (for example, Decimal).
Run an Update Query to update the record. You must do this instead of relying on the recordset update.
However, these 3 workarounds are not satisfactory. Only first could be, but this workaround didn't work - as expected. It probably works only with MS SQL Server.
Are there any other solutions/workarounds for this problem?
Additional details:
The MySQL server is just for me, nobody else is accessing it.
Insertion of new records was working fine.
Primary key is well defined for this table.
Restart of MS Access didn't help.
Deleting the link to the ODBC table and linking it again didn't help either.
Linking the table from brand new Access database didn't help.
Changing the MySQL database engine from MyISAM to InnoDB didn't help either.
There is no problem with permissions, there are all permission for this user#host.
I can normally delete the records from the MySQL console at the server without problem.
Trying to set MySQL Connector ODBC options didn't help: Allow big results, Enable automatic reconnect, Allow multiple statements, Enable dynamic cursors, Force use of forward-only cursors, Don't cache results of forward-only cursors.
I turned on debugging in MySQL ODBC connector, it created myodbc.sql log, but it didn't contain any corresponding queries when editing/deleting (don't know why).
More details about the structure of the linked table would be helpful, but I'll hazard a guess.
I've had a similar problem in both MS Access 2003 and 2010 when I included nullable boolean fields in the SQL Server linked table. Seems JET databases have a problem with nullable nit fields. Check out this answer for more information: https://stackoverflow.com/a/4765810/1428147
I fixed my problem by making boolean fields non-nullable and setting a default value. If your problem is the same as mine, but with MySQL, try doing the same.
I solved here the same issue. The solution was to remove Default Values from decimal fields in the table. I was able to keep decimal data type but just remove the default value I already defined before with 0.0000 and now I set to null and bug fixed.
My workaround was to copy the table data into excel, then use phpadmin to clear the table, then do the editing in excel and copy the 'new' data (ie, all of it, after editing) back to access.