![]() ![]() Table variables are created like any other variable, using the DECLARE statement. To create a global SQL temp table, you simply use two pound symbols in front of the table name. Which is something that I would recommend. You can always use the “DROP” command to clean it up manually. Like Local SQL Server temp tables, they are dropped once the session disconnects and there are no longer any more references to the table. Also note that anyone can DROP the table. Anyone can insert values, modify, or retrieve records from the table. Global SQL temp tables are useful when you want you want the result set visible to all other sessions. You can use the same name that you declared as it’s confined to that session. But this process is transparent to the developer/user. But it is entirely up to you and what you’re trying to accomplish.Īlso note, that in the event of name conflict (remember that SQL Server temp tables are created in the tempdb) SQL server will append a suffix to the end of the table name so that it is unique within the tempdb database. Many times you’ll see developers use the “DROP #Table_Name” command at the end of their statement just to clean up. The SQL temp table is dropped or destroyed once the session disconnects. But Session 1, which is above session 2, will not be able to see the SQL Server temp table. The sessions below it (sessions 3 and session 4) are able to see the SQL Server temp table. In this quick diagram, a SQL temp table is created in Session 2. If the session that we’re working in has subsequent nested sessions, the SQL Server temp tables will be visible in sessions lower in the hierarchy, but not above in the hierarchy. There is one point that I want to make however. Not only does this save on expensive query processing, but it may even make your code look a little cleaner. Why not just process this result set once and throw the records into a SQL temp table? Then you can have the rest of the sql statement refer to the SQL temp table name. Let’s say that you create a join, and every time you need to pull records from that result set it has to process this join all over again. See the code sample above, your loop can now reference the SQL Server temp table and process the records that meet the criteria of your goal.Īnother reason to use SQL Server temp tables is you have some demanding processing to do in your sql statement. It provides a quick and efficient means to do so. For example, you want to process data for a SQL statement and it you need a place to store items for your loop to read through. One of the most often used scenarios for SQL Server temp tables is within a loop of some sort. Here’s a quick example of taking a result set and putting it into a SQL Server temp table. It cannot be seen or used by processes or queries outside of the session it is declared in. A local SQL Server temp table is only visible to the current session. SQL temp tables are created in the tempdb database. Local SQL Server temp tables are created using the pound symbol or “hashtag” followed by the table name. SQL Server supports a few types of SQL Server temp tables that can be very helpful.īefore we proceed, if you want to follow along with any code samples, I suggest opening SQL Server Management Studio: Finally, you might be in a situation where you need the data to be visible only in the current session. Or you don’t have permissions to create a table in the existing database, you can create a SQL Server temp table that you can manipulate. You can use your existing read access to pull the data into a SQL Server temporary table and make adjustments from there. ![]() Let’s say you want full DDL or DML access to a table, but don’t have it. It is very beneficial to store data in SQL Server temp tables rather than manipulate or work with permanent tables. ![]()
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