They take care of security and maintain data backups. Execution of SQL commands can be done by SQL developers but changes must be approved by the DBA, as ultimately they are responsible for maintaining the structure and security of the database. Developers should not create SQL commands as this may cause data conflicts. Sometimes they might not know the complete structure of the database. For example, if a query needs to be written to generate reports, if the application developer writes the query, it can only be used in the application, but if a SQL developer writes the query, it can be used by the application developer and also independently to generate reports. Because the SQL developer puts the queries into the database as a view that the developer and others can access. End users should not run queries because they may also not know the structure except understanding the functionality. Basic troubleshooting queries can be run by the database administrator, but in case of a larger problem, SQL developers can resolve them because they understand the low level better.