Using the data in the tables

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Using the data in the tables

At the end of the article, I briefly discuss the particular situation when your stored procedures are on different serverswhich is a quite challenging situation. A related question is how to pass table data from a client, but this is a topic which is outside the scope for this text, but I discuss this in my article Using Table-Valued Parameters in SQL Server and.

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Examples in the article featuring tables such as authors, titles, sales etc run in the old sample database pubs. Some examples use purely fictive tables, and do not run in pubs. Nevertheless, this is a method that is sometimes overlooked.

Say you have this simple stored procedure: Rewrite this procedure as: Table-valued Functions When all you want to do is to reuse the result set from a stored procedure, the first thing to investigate is whether it is possible to rewrite the stored procedure as a table-valued function. This is far from always possible, because SQL Server is very restrictive with what you can put into a function.

But when it is possible, this is often the best choice. There are two types of table functions in SQL Server: That is, you use the function just like was a table or a view. You could say that an inline function is a parameterised view, because the query optimizer expands the function as if it was a macro, and generates the plan as if you had provided the expanded query.

Using the data in the tables

For this reason, when you want to reuse a stored procedure that consists of a single SELECT statement, rewriting it into an inline UDF is without doubt the best choice. Two examples are newidand rand.

Using the data in the tables

A typical example is getdate. Multi-statement Functions A multi-statement function has a body that can have as many statements as you like.

You need to declare a return table, and you insert the data to return into that table. Here is the function above as a multi-statement function: This permits you to move the code of a more complex stored procedure into a function. As you can see in the example, you can define a primary key for your return table.

I like to point out that this definitely best practice for two reasons: It states your assumptions of the data. If your assumptions are incorrect, you will be told up front. Instead of spending time to understand why your application presents incorrect data. This information is valuable to the optimizer when you use the function in a larger query.

It goes without saying, that this is only meaningful if you define a primary key on the columns you produce in the body of the UDF. Compared to inline functions, multi-statement functions incur some overhead due to the return table. More important, though, is that if you use the function in a query where you join with other tables, the optimizer will have no idea of what the function returns, and will make standard assumptions.

This is far from always an issue, but the more rows the function returns, the higher the risk that the optimizer will make incorrect estimates and produce an inefficient query plan. One way to avoid this is to insert the results from the function into a temp table. Since a temp table has statistics this helps the optimizer to make a better plan.

When compiling the query, they first run the function, and once the optimizer knows the number of rows the function returns, it builds the rest of the plan based on this. However, because of the lack of distribution statistics, bouncing the data over a temp table may still yield better results.

User-defined functions are quite restricted in what they can do, because a UDF is not permitted to change the database state.At the end of the article, I briefly discuss the particular situation when your stored procedures are on different servers, which is a quite challenging situation.. A related question is how to pass table data from a client, but this is a topic which is outside the scope for this text, but I discuss this in my article Using Table-Valued Parameters in SQL Server monstermanfilm.com Marking Up Data Tables.

The purpose of data tables is to present tabular information in a grid, or matrix, and to have column or rows that show the meaning of the information in the grid.

These tutorials step you through using Fusion Tables’ features to accomplish neat things with your data. See what others have done in the Example Gallery. Basic tutorials Get started using Fusion. I have a test environment for a database that I want to reload with new data at the start of a testing cycle.

I am not interested in rebuilding the entire database- just simply "re-setting" the dat. Marking Up Data Tables. The purpose of data tables is to present tabular information in a grid, or matrix, and to have column or rows that show the meaning of the information in the grid.

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Manage Retention of Historical Data in System-Versioned Temporal Tables | Microsoft Docs