Application programming interface (API): API are a set of function calls which are used by the application program to communicate with the database management system.
Here’s how the SQL API works:
1) Database access is achieved by using API calls which are used to connect the application program to the DBMS. The DBMS is in turn connected to the database.
2) SQL statement is sent to DBMS by creating SQL statements as a text string in buffer. Then, API call is made to send the buffer to DBMS.
3) API calls are made by the application program to check status of request and for handling errors.
4) API calls are used for retrieving query results in buffer.
5) When all the tasks are finished, API call is used for disconnecting the application program from the DBMS.
SQL API in client/server architecture: In a client/server architecture, API function codes are present in client systems, and DBMS software in the server. Application programs call to the API in the client system and they are send as messages to the DBMS. Advantage of client/sever architecture is that it reduces network traffic between API and DBMS.