What is the difference between VOImpl and VORowImpl in Oracle ADF?
What is the difference between VOImpl and VORowImpl in Oracle ADF?
The VOImpl represents all rows that are queried by the VO.
The ViewRowImpl represents ONE row from the set represented by the VOImpl.
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In this dataset I am trying to develop a column or a measure based upon the hours column. I am trying to determine the difference between the first and second hour rows, the second and third hour rows, etc. and all the way through the entirety of the data.
Note: there are multiple serial numbers in this table; I just used this serial as an example.
I'm not sure this should be tagged with SQL-Server unless you can change the SQL that sources the data. If so you could pre-calculate this inside SQL Server.
If you can change the Power Query that brings the data into the data model you can add an Index column as the data's coming in and use that.
Please see:
How to Compare the Current Row to the Previous Row Using DAX
When using the database manipulation nodes, does the original database data would change or remain the same?
Can anyone answer please?
If you write to or update the database, the original database will be updated. Read or query operations such as row / column filtering, row sampling, groupby and joiner do not change the underlying database
Note: this question is referencing an old EF Core issue. See this answer for a discussion relevant to EF Core 5.
I'm seeing conflicting information about this. LearnEntityFrameworkCore.com says you can write
.HasComputedColumnSql("GetUtcDate()");
The value of the column is generated by the database's GetUtcDate() method whenever the row is created or updated
However, in the technet documentation for computed columns on SQL Server it says:
Their values are recalculated every time they are referenced in a query.
The two documentation you referenced are correct. Each is talking about different methods. There are several overloads for this method. You can check this over here (search for "HasComputedColumnSql" in the browser).
If there are triggers in the database that define values for this column, you will use the HasComputedColumnSql() implementation.
If you want to store a computed value on the property, but don't want it to persist in the table, you will use the HasComputedColumnSql("SomeFunction()") implementation.
If you want to store the value in a column, you will use the implementation HasComputedColumnSql("SomeFunction()", stored: true).
Good question. It's unclear from EF Core documentation what type of computed column does HasComputedColumnSql represent. Probably because it's a part of the relational extensions, thus is considered provider specific. But since it has no configuration options, I agree that the behavior should be specified.
A quick test with SQL Server shows that the created column is not physically stored (no PERSISTED option used), and actually it can't since GetUtcDate is not deterministic. Hence the LastModified example from the first link is incorrect - the column will be recalculated any time it's been read, so it cannot be used for the desired intent, and should be created as normal column and updated by the code.
Looks like the intended usage in EF Core is to allow simple calculation based on other columns like FullName or using database specific conversion function with data not stored properly (for instance numeric/date time data stored as text) etc.
I am using hibernate to map my classes to oracle database. But when I try to insert something ,get:
java.sql.BatchUpdateException: ORA-12899: value too large for column
I used hibernate tool to generate this table, is there anyway I can manually change the setting of the column size?
I tried to set the length="1000" in hbm.xml file and #Column(length=1000) in object class, but those are not working.
Thank you.
How large is your actual value? You might consider using a Lob as the max size in oracle for something like a varchar is 4000. You could use the #Lob annotation on the field/setter if you wanted to go this right.
I have some data with a timestamp in SQL Server, I would like to store that value in sqlce with out getting fancy to compare the two values.
What is the SQL Server timestamp equivalent in sqlce?
Timestamp is from MS Docs
timestamp is a data type that exposes automatically generated binary numbers, which are guaranteed to be unique within a database. timestamp is used typically as a mechanism for version-stamping table rows. The storage size is 8 bytes.
This value makes no sense outside the database it was created in. Thus I don't see how it can be converted.
In a non Sybase/ SQL Server database I would use a version number or last updated column
AS of Sql Compact 3.5, there is support for timestamps, per MSDN:
SQL Server Compact implements the
timestamp (rowversion) data type. The
rowversion is a data type that exposes
automatically generated binary
numbers, which are guaranteed to be
unique in a database. It is used
typically as a mechanism for
version-stamping table rows.
Ok the timestamp is a varbinary that auto generates. So to copy a time stamp you need a varbinary field.