I have a database called Students. DB has a "status" string field with 3 possible values; missing, absent, present. I have Calculated SQL DB called "stats". In the "stats" I have a "name" and "number" fields.
I'm stuck adding scripting that can load a chart with a total number of missing, present, and absent students.
Related
A new column was added to an existing DB table (PA0023).
DB: HANA
The column should be unique, therefore i tried to create a unique index constraint via SE11.
Activation succeeded. However, while creating the index via Utilities... Database Utility, an error showed up:
Request: Create Index PA0023-Z01
...
sql:
CREATE UNIQUE INDEX 'PA0023~Z01' ON 'PA0023'
('MANDT',
'RECORD_KEY')
cannot CREATE UNIQUE INDEX; duplicate key found [5] Several documents with the same ID exist in the index;SAPABAP1:PA0023.$uc_PA0023~Z01$ content not unique, cannot define unique constraint. rowCount != distinctCount.
There aren't rows with the same value filled in that column. There are rows with blank value, which are considered duplicates. After replacing blanks in development environment, index was created well. It's less possible in production, because there are many records with an empty value in that new field.
So my question is: Is there a way to create the unique constraint without replacing the blanks?
You cannot create a unique constraint if the existing data does not provide uniqueness. So no you can't do this if you have multiple NULL values for the key. You would need to ensure the data is unique before creating the constraint.
This is normal database practice, it's not HANA specific.
While it is true that a compound primary key cannot contain any nullable columns it is permitted for a compound unique/candidate key to be defined with nullable columns. The only golden rule is that when adding or updating a record if any column in the unique key contains a NULL value then the index entry is NOT written to the database.
MySQL does this by default.
SQL Server will do this provided that you add "WHERE columnX IS NOT NULL" to the key's definition.
ORACLE is the same as SQL Server, except that the syntax is more complicated.
In my DB, some of values of a column (called status) are null, and if they are null, I want to show a String "canceled".
Guess I need to do it on Attributes - common -if-null but then don't know how to specify it.
Can anyone help me?
There are multiple options, as you said, Attributes - common - if-null on the field containing the status should do that, you can specify a String by entering it in the Value box. If your string disappears after unfocusing, click the ... while the Value entry is selected, that will launch a Popup-entrybox.
Alternatively, you could put that logic into your query
select coalesce(status, 'Cancelled')
from table
COALESCE
Evaluates the arguments in order and returns the current value of the first expression that initially doesn't evaluate to NULL. For example, SELECT COALESCE(NULL, NULL, 'third_value', 'fourth_value'); returns the third value because the third value is the first value that isn't null.
Some databases might have similar functions with different names, with Oracle e.g. there's nvl()
I am new to SSAS and I'm having some trouble with a "count of rows" measure.
I'm doing this all with named queries from a MySQL database and have created two logical tables in my DSV. The first table is called "Person" and has a primary key of "Person GUID". The second is called "Role" and has a primary key of "Role GUID" and a foreign key of "Person GUID". This is acting as a dimension table and also has an attribute of "Role Name".
What I want to do is be able to select a role from my dimension table and have this show me the number of people in that role, using a "count of records" measure from the Person table. The problem is, people can hold multiple roles, and the way it is structured in my "Role" table is that there is a separate row for each role that a person might have...in other words, "Person GUID", which is how it is mapped to the measure group, could be duplicated many times.
This is not working in SSAS - It doesn't seem to be giving me an accurate count. It appears to be only considering the role of the first instance of a particular Person GUID.
I know that I must be looking at this the wrong way...any help that anyone could offer would be much appreciated. I understand that I could just do a count of rows on the "Roles" table and then be done with it but because I have other dimensions that I want to correlate with it that are also mapped to the "Person" table, this isn't an acceptable solution for me. (These other dimensions have "Person GUID" as the primary key and thus don't have the same problem)
Sounds like you need to model a many to many dimension relationship between the person fact table and role dimension.
Your current role dimension sounds like it needs to be split out into a new bridge table mapping persons to roles. The other table is a simplified role table joining to the mapping table.
I need to create a data flow for an existing MS SSDT project that inports a flat CSV file into an existing database table. So far so good.
However I would like to reject all entries where the column "code" match values already stored in the db. Even better, if possible, in the case that the column "code" maches an entry in the database, I would like to update the column "description". The important thing is that under no circumstances should duplicate code entries be created.
Thanks
Ok so seeing as I figured it out, I thought someone else might find it useful:
The short answer is that a lookup is needed between the data source and destinations. This "lookup" will filter between matches that need updating and new values that need to go straight into a new table row (see image).
Values that match the database and need updating to the description need to be fed into an "OLE DB command".
Within the "lookup" component we need to do the following:
Go to the general tab and select Redirect rows to no match output
Go to the connection tab and insert the following SQL:
SELECT id, code FROM tableName
Go into the "Columns" tab and check the "id" column on the "Available lookup Columns" table. Also chech the "code" column and drag it to its corresponding "Available Inputs Columns" counterpart to map them to eachother so that the look up can compare them.
-- At this point if you get an error caused by the mapping, try to replace the code in setep 2 with:
SELECT id, CAST(code AS nvarchar(50)) AS code FROM tableName
In the Error Output, ensure that id under "Lookup Match Output" has a description of "Copy Column"
Now we need to configure the "OLE DB command" component:
Go to the "Connection Managers" tab and ensure the component is connected to the desired DB
Go to "Component Properties" and add the following code to the "SQLCommand" property:
UPDATE tableName SET description = ? WHERE id = ?
Note the "?". It is supposed to be there to indicate a parameter must be added to the "Column Mappings" tab, do not replace them.
Finally go into the "Column Mappings" tab and map Param_0 (the first ?) to the "description" column and "Param_1" to the "id" column. No action is needed on the "code" or any other column the db table may contain.
Now give yourself a big pat on the back for having completed a task, that in SQL would normally be one line of code, in about 10 time-consuming steps ;-)
This is odd because I'm not inserting data, I'm pulling data with a query.
I'm trying to run
SELECT DISTINCT description FROM products;
Which outputs the error "The field is too small to accept the amount of data you attempted to add.".
However, running the following doesn't produce the error:
SELECT description FROM products;
So I'm confused as to what the issue would be.
I'm using OleDbDataReader and taking data out of an mdb database file.
This might be related to: http://support.microsoft.com/kb/896950/us
This problem occurs because when you
set the UniqueValues query property to
Yes, a DISTINCT keyword is added to
the resulting SQL statement. The
DISTINCT keyword directs Access to
perform a comparison between records.
When Access performs a comparison
between two Memo fields, Access treats
the fields as Text fields that have a
255-character limit. Sometimes Memo
field data that is larger than 255
characters will generate the error
message that is mentioned in the
"Symptoms" section. Sometimes only 255
characters are returned from the Memo
field.
Workaround:
To work around this problem, modify
the original query by removing the
Memo field. Then, create a second
query that is based on both the table
and the original query. This new query
uses all the fields from the original
query, and this new query uses the
Memo field from the table. When you
run the second query, the first query
runs. Then, this data is used to run
the second query. This behavior
returns the Memo field data based on
the returned data of the first query.