From T-SQL to E-SQL

SQL is the primary language that has been in use for years for querying databases. Remember, SQL is a standard and not owned by any particular database vendor. SQL-92 is a standard, and is the most popular SQL standard currently in use. This standard was released in 1992. The 92 in the name reflects this fact. Different database vendors implemented their own flavors of the SQL-92 standard.

The T-SQL language was designed by Microsoft as an SQL Server implementation of the SQL-92 standard. Similar to other SQL languages implemented by different database vendors, the E-SQL language is Entity Framework implementation of the SQL-92 standard that can be used to query data from the EDM.

E-SQL is a text-based, provider independent, query language used by Entity Framework to express queries in terms of EDM abstractions and to query data from the conceptual layer of the EDM.

One of the major differences between E-SQL and T-SQL is in nested queries. Note that you should always enclose...