The process the SQL Server Query Optimizer uses for determining how a query or stored procedure is executed. During a compile, the Query Optimizer examines the query, including the tables, clause conditions, joins, sub queries, sort and grouping requirements used. The Optimizer then takes into account all of the existing indexes, locking methods and join algorithms that could help the query run faster. The result of this process is what the SQL Server Query Optimizer considers to be the fastest way of executing the query. This is known as the execution plan.
A program used for establishing and maintaining a connection between a client program and SQL Server. The connectivity software usually used under SQL Server is Microsoft Data Access Components (see ).