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Microsoft SQL Server is a Relational Database Management System(RDBMS) developed by Microsoft. It is one of the most popular RDBMS. SQL server has evolved from sql 1.0 in 1989  to the latest release of SQL Server 2019 (preview)  to become one of the best enterprise level database server's. SQL server is released with different editions. Express: Free to use entry level database which can use 1 core cpu, 1 GB ram and have maximum size of 10GB. Compact : Free embedded database for mobile app development and can have maximum size of 4GB. Enterprise : Full featured top end edition. Standard : Have less features than enterprise. WorkGroup: suitable for a company to use among the group. Developer: Same features like enterprise but is  licensed  to one user only. Web: Specially targeted for web application There are some other editions like Datacenter, Enterprise evaluation and Business Intelligence. These all editions are not available on all version o...

  At different point of time we come up with a situation  where we need to update a column in a table from another  table based on some condition.   So a Basic Syntax for update is: UPDATE table SET column1 = expression1, column2 = expression2, ... [WHERE conditions]; For us to update based on another table we will be using the same syntax for update applying join with another table from  where we need the data. UPDATE t1 SET t1 .column_to_update = t2 .column_from_update FROM Table1 t1 INNER JOIN Table2 AS t2 ON t1 .common_column = t2 .common_column

This issue is related with the permission for application pool to connect with the sql. We can create login user with the name as specified in the exception  IIS APPPOOL\<name> and grant permission to the database. We can create new login user by opening the SSMS(Sql server management studio) navigate to Security>Login  Then Add the user by right clicking Login and selecting new login While creating user Navigate to UserMapping and tick the database for the specific user. This process will create the new user and gran permission to the user. Another Work Around Yet another simple way will be to change the application pool Identity property  To LocalSystem by navigating to the application pool and then advance setting.