SQL – PROS AND CONS

PROS AND CONS – Independence from a specific DBMS
Despite the presence of dialects and syntax differences, most of the SQL query texts containing DDL and DML can be easily transferred from one DBMS to another. There are systems whose developers initially focused on using at least several DBMS. Naturally, it is already very difficult to achieve such portability when applying some specific features.

Availability of standards

Availability of standards and a set of tests to identify compatibility and compliance of a particular SQL implementation with a common standard only contributes to the “stabilization” of the language. However, it is worth noting that the standard itself is in some places too formalized and expanded in size.

Declaracy of PROS AND CONS

With SQL, the programmer only describes what data should be extracted or modified. The way of doing this is decided by the DBMS directly when processing the SQL query. However, one should not think that this is a completely universal principle – the programmer describes the data set to be extracted or modified, but it is useful to imagine how the DBMS will parse his query text. The more complex the query is designed, the more writing options it allows, varying in execution speed but equal in the final data set.

Disadvantages of Mismatching relational data model

The creators of the relational data model Edgar Codd, Christopher Data and their supporters point out that SQL is not truly a relational language. In particular, they point to the following SQL problems:

• Repeating rows
• Undefined values
• Clear indication of column order from left to right
• Columns without name and duplicate column names
• Lack of support for the “=” property
• Using pointers
• High redundancy

In the Manifesto published by Christopher Data and Hugh Darwen the Third, they set out the principles of the next generation DBMS and offer the language Tutorial D, which is truly relational.

The Challenge

Although SQL was conceived as an end user tool, it eventually became so complex that it became a programming tool.

Deviations from standards

Despite the presence of the international standard ANSI SQL-92, many companies engaged in DBMS development make changes to the SQL language used in the developed DBMS, thus deviating from the standard. Thus, there are dialects of SQL language specific for each DBMS.

Difficulty of Working with Hierarchical Structures

Previously, SQL dialects of most DBMS did not offer a way to manipulate tree structures. Some DBMS vendors offered their solutions. At present, ANSI standardizes the WITH recursive construct from the SQL DB2 dialect. In MS SQL Server recursive queries appeared only in MS SQL Server 2005 version.