JSON Recursive queries OOP principles Multithreaded applications development Aggregate functions SQL Server data retrieval SQL Server data selection Transaction isolation levels Query and stored procedures optimization Identifying problematic procedures System objects functions XML Data storage in databases Understanding of locking types and transaction isolation levels System objects tables System objects views Query optimization methods Standard libraries High-load large databases Delphi syntax Types of blocks and physical operations Identifying problem areas in execution plans Correlating blocks in plans with executed query code Intricacies of multithreaded programming Call stack Understanding sequence of actions in the call stack Stored procedures Relational DBMS principles VCL Capabilities of SQL Server Profiler MS SQL Server syntax T-SQL User Defined Functions (UDF) Delphi XE 10 or above SQL Server Profiler Indexes Nuances of different types of indexes Execution plans Debugging programs MS SQL Server 2016 and above Locking types Error handling Understanding others' code Classes for multithreading Analytical functions System objects procedures Overall structure of queries and stored procedures Delphi 2009 or later Delphi development environment Databases via ADO Internals of Delphi