Updating tables in sql from another table
Some of the new features target specifically temporary objects, whereas others are more general and just happen to effect temporary objects as well.
The examples in this articles demonstrating the new features use a sample database called Performance V3.
As you may remember from Chapter 12, these anti-joins can often be replaced with an outer join. Now, we rewrite the same query to utilize temporary tables by selecting the distinct values from each table.
With the addition of temporary tables to hold the intermediate results, this query runs in less than three seconds, a 6 performance increase.
The expression cannot be a subquery or contain alias data types.
Computed columns can be used in select lists, WHERE clauses, ORDER BY clauses, or any other locations in which regular expressions can be used, with the following exceptions: Based on the expressions that are used, the nullability of computed columns is determined automatically by the Database Engine.
You can pass composite variables to subprograms as a parameters.
To create a collection or record variable, you first define a collection or record type, and then you declare a variable of that type. A collection that is created in a PL/SQL block (with the syntax in Collection) is available only in that block.
SQL Server 2014 introduces a number of gems that can make your solutions faster: support for inline index definitions, memory optimized table types and table valued parameters (TVPs), parallel SELECT INTO, relaxed eager writes and improved cardinality estimates for table variables.
The last two improvements were also "backported" to SQL Server 2012.
] table_name ( [ PERIOD FOR SYSTEM_TIME ( system_start_time_column_name , system_end_time_column_name ) ] ) [ WITH ( can be a maximum of 128 characters, except for local temporary table names (names prefixed with a single number sign (#)) that cannot exceed 116 characters.
Is an expression that defines the value of a computed column.
For certain types of SQL operations, the creation of intermediate result tables can result in stunning performance improvements.