Nvarchar criteria null

NULL is not the same as an empty string, or a value of zero. Conceptually, NULL means "a missing unknown value" and it is treated somewhat differently from other values. If you have columns that may contain "a missing unknown value", you have to set them to accept NULLs. On the other hand, an empty string simply means that the value is known , but is empty. The user might or might not have a middle name.

However, if the "Middle Name" field is set to an empty string, this should mean that the user is known to have no middle name. What ho1 said. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Asked 11 years, 7 months ago. Active 11 years, 7 months ago. Viewed 10k times. Improve this question. Anders Abel Anders Abel Well, Oracle agrees with you and treats empty strings as null.

This would avoid any chance of null values occurring when using an attribute. Now, the above is all good and fine — the solution is straightforward you are saying. I can just insert a record into the dimension tables required in each environment required, right? We need to create a stored procedure that inserts a whitespace row into every table in a target schema.

In my case, this was an SLT managed schema, so some elevated rights are needed. Although it's tempting to solve the missing data issue en block, typically it's not advisable to do that. Once the data is free of NULLs, you could actually go a step further and replace the outer join with an inner join speeding up the join processing. The issue was not that NULL values were being delivered from ECC, in fact in my real examples I was getting proper default '' values in the fact tables per their definition.

The problem comes when I don't have a matching blank '' value in the dimension to which the fact is joined, when the fact has a blank '' in the joined column.

Take another look at the SQL example in the setup above before the fix was applied, and I think it will become more clear. On another note - you mention inner joins speeding up processing vs.

I actually found the opposite to be true when only using the joined key column per Analytic View Modeling: Using attribute on fact instead of attribute view? However, I don't have any real evidence to support using any of the non-joined attribute columns. Do you have anything to share in this regard?

Always looking for an edge in processing! You're right, that's what we always generate into the dimension tables to avoid the NULLs that are generated by non-matching records during the outer join. Concerning the possible optimization for the outer join you mentioned in your other blog post: correct, as long as the join cardinalities in the analytic view are setup correctly n:1 that is the OLAP engine can figure out that the result set won't be changed by performing the join and then skip it, when you don't actually want to see data from the joined table.

Set the cardinality wrong or force the join otherwise to be executed and you should see a different picture. Well, I wouldn't say it was "all about" BW per se, but it was an obvious correlation after thinking about it for some time, its the same solution to the same problem.

Not to beat the join topic to death, but the analysis in that link shows that in the scenario that only the joined column is requested from the right table, the LOJ does not perform a join, but the Referential does. So in that regard, it would mean to me that the LOJ is cheaper since it can be smarter about when the join is really required.

In Referential, if any column from the right table is selected, it will join. In the LOJ, if any column other than the joined column is selected, it will join. Oh, and I should point out too, that in BW master data there is always a row with a blank '' value present to avoid such situations. Update the original post with that info too. Am I correct that while that is fine for cross-client reporting, if one would want to report by session client the insert needs to specify the wanted client id?

When prefixing a string constant with the letter N, the implicit conversion will result in a UCS-2 or UTF string if the constant to convert does not exceed the max length for the nvarchar string data type 4, Otherwise, the implicit conversion will result in a large-value nvarchar max. Each non-null varchar max or nvarchar max column requires 24 bytes of additional fixed allocation, which counts against the 8,byte row limit during a sort operation. These additional bytes can create an implicit limit to the number of non-null varchar max or nvarchar max columns in a table.

No special error is provided when the table is created beyond the usual warning that the maximum row size exceeds the allowed maximum of 8, bytes or at the time of data insertion. This large row size can cause errors such as error that users may not anticipate during some normal operations.

Two examples of operations are a clustered index key update, or sorts of the full column set. For information about converting character data, see char and varchar Transact-SQL.

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