we are evaluating memsql to port our mysql Web App to Memsql.
Mainly our software is developed using .net on windows platform.
Last year we ported the Database layer to mysql on a linux server. First we had the problem that a select on a Table was case sensitive, because in .Net and windows it was not a problem to mix cases in Table names. This means if the table is named Test1 in Database, you were able to do: Select * from tesT1 and you received the result.
After running against mysql the Select failed.
Then we set parameter lowercase_table_names = 1 in my.cnf of mysql and the Select worked again.
Is there a similiar setting for memsql?
best regards
Kai
Kai,
No, there's no similar setting in MemSQL.
If number of ways you spell your tables is not very large (e.g. it's either table1 or Table1), then you can create views with different spellings you use, as in:
CREATE VIEW Table1 AS SELECT * FROM table1;
Selecting from such view is as fast as selecting from the table itself.
Related
I am trying to connect to my organisation's SQL database using Power Query to create some reports. I need to delete/edit some tables and join multiple tables to come up with the desired report output...
I don't want the change or edit I will do on the excel-power query to reflect on the live database but just in excel .
The short answer is no, any button you press in the Power Query Editor interface does not modify the source database. I must admit that I have not found any page in the Microsoft Docs on Power Query that states this clearly. The page What is Power Query? states that:
Power Query is a data transformation and data preparation engine. Power Query comes with a graphical interface for getting data from sources and a Power Query Editor for applying transformations.
Other pages contain similarly general and vague descriptions but let me reassure you that any data transformation you carry out by using the Power Query Editor interface will not modify your SQL database. All you see in Power Query is a view of the source database.
Seeing as you are connecting to a SQL database, it is likely that query folding is activated. This means that when you remove a column (or row), this will update the SQL query used to extract the data from the database. That query is written as a single SELECT statement that can contain multiple clauses like GROUP BY and WHERE. Transformations that add data (e.g. Add Custom Column, Fill Down) are not included in the query, they are carried out only within the Power Query engine. You can read more about this in the docs.
How to edit a database with Power Query when native SQL queries are supported
That being said, you can actually edit a database from within Power Query if the database supports the use of native SQL queries, if you have write permission for the database, and if you edit and run one of the two M functions that let you write native SQL queries. Here is an example using the Sql.Database function:
Sql.Database("servername", "dbname", [Query = "DROP TABLE tablename"])
And here is an example using the Value.NativeQuery function:
Source = Sql.Databases("servername"){[Name="dbname"]}[Data],
#"Native Query" = Value.NativeQuery(Source, "DROP TABLE tablename")
Unless you have changed the default Query Options, these functions should raise a warning message requiring you to permit running the query:
This prevents you from modifying the database without confirmation, so any database modification cannot happen just by accident.
I verified this using Excel Microsoft 365 (Version 2108) on Windows 10 64-bit connected to a local SQL Server 2019 (15.x) database.
I am experiencing a strange bug with generated columns and MariaDB running in a Docker container.
The image I'm using is mariadb:10.
I have been trying to add generated columns. The first column I add works fine; the second I add crashes the container and destroys the table.
Here's the first column that is working:
ALTER TABLE program
ADD is_current tinyint AS (
IF (
status IN ('active', 'suspended')
AND start_date >= NOW(),
1,
0
)
);
This one works just fine. The following SQL crashes the container:
ALTER TABLE program
ADD is_covered tinyint AS (
IF (
status IN ('active', 'suspended')
AND start_date <= NOW(),
1,
0
)
);
After restarting the container, I get the following errors:
SELECT * FROM program;
[42S02][1932] Table 'my_local.program' is marked as crashed and should be repaired
repair table my_local.program;
Table 'my_local.program' doesn't exist in engine / operation failed
Following the directions from this question I checked in the container for the existence of the ibdata1 file. It exists, as do the table's .ibd and .rfm files.
I have not been able to fix this; I had to drop the table and re-create it and re-import the data.
If anyone has any suggestions, I'd love to hear.
Checking the reference for MySQL 8 for generated columns I find that
Literals, deterministic built-in functions, and operators are
permitted. A function is deterministic if, given the same data in
tables, multiple invocations produce the same result, independently of
the connected user. Examples of functions that are nondeterministic
and fail this definition: CONNECTION_ID(), CURRENT_USER(), NOW().
This is also true of MySQL 5.7.
When I attempted to create your generated column with MySQL 8 I got this message:
Error Code: 3763. Expression of generated column 'is_covered' contains a disallowed function: now.
I note, however, that you are using mariadb:10. Although it is derived from MySQL, MariaDB is now effectively a different product.
The MariaDB reference for generated columns says: (for 10.2.1 onwards):
Non-deterministic built-in functions are supported in expressions for not indexed VIRTUAL generated columns.
Non-deterministic built-in functions are not supported in expressions for PERSISTENT or indexed VIRTUAL generated columns.
So, If you have MySQL you can't do this at all. If you have MariaDB 10.2.1+ you should be able to do it with certain limitations.
In any case, you should get an error message, not a crashed table. I suggest you check the MariaDB bug reports, and submit one if this is not already there.
My client has decided they want to rename a very commonly used data item name.
So, for example, the database has a column called 'Cost' and they see 'Cost' on a heap of reports.
The client now wants to see 'Net Cost' everywhere.
So we need to change every occurrence of 'Cost' and change it to 'Net Cost'
I can do this in Framework Manager easily enough, and I can even run Tools > Report Dependency to find all the reports that use the 'Cost' column. But if there's 4,000 of them, that's a lot of work to update them all.
One idea is to deploy the entire content store to a Cognos Deployment zip file, extract that & do a global search & replace on the XML. But that's going to be messy & dangerous.
Option 2 is to use MotioPI to do a search & replace. I don't think the client will spring for buying this product just for this task.
Are there other options?
has anyone written anything in the Cognos SDK which will do a rename?
has someone investigated the Content Store database to the degree
that they could do a rename on all the report specs in SQL?
are there other options I've overlooked?
Any ideas would be greatly welcomed ...
Your first option is the way to go. This essentially boils down to an XML find-and-replace scenario. You'll need to isolate just the instances of the word "Cost" which are relevant to you. This may involve the start and end tags.
To change the data source reference across reports, you'll need to find and replace on the three part name [Presentation Layer].[Namespace].[Cost]. If there are filters on the item, they may just reference the one part name from the Query. Likewise, any derived queries would reference the two part name. Handle these by looking through the XML report spec and figuring out how to isolate the text.
I'm assuming your column names are set to inherit the business name from the model and not hard coded (Source Type should be Data Item Label, NOT Text). If not, you'll need to handle these as well. Looking at the XML, you would see <staticValue>Cost</staticValue> for these.
It's not really dangerous as you have a backup. Just take multiple passes, each with as granular a find and replace as possible.
Motio will just look at the values inside the tags, so you will be unable to isolate Cost, thus it can't be used for this. However, it would come in handy for mass validation of reports after the find and replace. A one seat license for the year could be justified by the amount of development time it could save here.
Have you tried using DRU? (http://www-01.ibm.com/support/docview.wss?uid=swg24021248)
I have used this tool before to do what you are describing.
Good luck.
You can at least search for text in the Content Store (v10.2.1) using something like:
set define off
select distinct T4.name as folder_name, T2.name as report_name
from cmobjprops7 T1
inner join cmobjnames T2 on T1.cmid=T2.cmid
inner join cmobjects T3 on T1.cmid=T3.cmid
inner join cmobjnames T4 on T3.pcmid=T4.cmid
inner join ( -- only want the latest version (this still shows reports that have been deleted)
Select T4.name as folder_name, T2.name as report_name, max(T3.modified) as latest_version_date
from cmobjnames T2
inner join cmobjects T3 on T2.cmid=T3.cmid
inner join cmobjnames T4 on T3.pcmid=T4.cmid
Where T2.Name like ‘%myReport%’ -- search only reports with 'myReport' i the name
and substr(T4.name,1,1) in ('Project Zeus','Project Jupiter') -- search only folders with this in the name
Group by T4.name, T2.name
) TL on TL.folder_name=T4.name and TL.report_name=T2.name and TL.latest_version_date=T3.modified
where T1.spec like '%[namespace].[column_name]%' -- text you want to find
and substr(T4.name,1,2) in ('Project Zeus','Project Jupiter')
order by 1 desc, 2;
I have some apps that connect to ODBC databases using ADO, and BDE. I have to call GetTableNames to return a list of table. Sometimes, I find that the table names are qualified with owner names, and sometimes not. The permutations are mysterious to me. Anyone can shed light on this?
Most DBMS these days provide a way to retreive a list of tablenames in a result set. I would suggest this approach rather than using the built in GetTableNames function.
For example, on MySQL it is
SHOW TABLES
on MS SQL Server it is:
SELECT name FROM <database name>..sysobjects where xtype = 'U';
Hope that helps
Let's say I have 'myStoredProcedure' that takes in an Id as a parameter, and returns a table of information.
Is it possible to write a SQL statement similar to this?
SELECT
MyColumn
FROM
Table-ify('myStoredProcedure ' + #MyId) AS [MyTable]
I get the feeling that it's not, but it would be very beneficial in a scenario I have with legacy code & linked server tables
Thanks!
You can use a table value function in this way.
Here is a few tricks...
No it is not - at least not in any official or documented way - unless you change your stored procedure to a TVF.
But however there are ways (read) hacks to do it. All of them basically involved a linked server and using OpenQuery - for example seehere. Do however note that it is quite fragile as you need to hardcode the name of the server - so it can be problematic if you have multiple sql server instances with different name.
Here is a pretty good summary of the ways of sharing data between stored procedures http://www.sommarskog.se/share_data.html.
Basically it depends what you want to do. The most common ways are creating the temporary table prior to calling the stored procedure and having it fill it, or having one permanent table that the stored procedure dumps the data into which also contains the process id.
Table Valued functions have been mentioned, but there are a number of restrictions when you create a function as opposed to a stored procedure, so they may or may not be right for you. The link provides a good guide to what is available.
SQL Server 2005 and SQL Server 2008 change the options a bit. SQL Server 2005+ make working with XML much easier. So XML can be passed as an output variable and pretty easily "shredded" into a table using the XML functions nodes and value. I believe SQL 2008 allows table variables to be passed into stored procedures (although read only). Since you cited SQL 2000 the 2005+ enhancements don't apply to you, but I mentioned them for completeness.
Most likely you'll go with a table valued function, or creating the temporary table prior to calling the stored procedure and then having it populate that.
While working on the project, I used the following to insert the results of xp_readerrorlog (afaik, returns a table) into a temporary table created ahead of time.
INSERT INTO [tempdb].[dbo].[ErrorLogsTMP]
EXEC master.dbo.xp_readerrorlog
From the temporary table, select the columns you want.