Chapter 13: JDBC Connectivity JDBC Basics JDBC is
Chapter 13: JDBC Connectivity JDBC Basics JDBC is a programming interface for accessing RDBMSs. Its operation is based on the transmission and execution of Structured Query Language (SQL) on the database server. SQL is a text-based query language for performing operations with data stored in a relational database. In fact, JDBC is based on a Call-Level Interface (CLI) to an engine that processes SQL statements. More specifically, JDBC uses the X/Open SQL CLI (X/Open is an international standards organization) conforming to the SQL92 language syntax standard. Figure 13-1 illustrates how SQL CLI, and therefore JDBC, operates under the hood. Java applications JDBC library JDBC driver SQL CLI processor Data tables Translated or pass-through command line SQL Returned results or status code Java API calls JDBC API RDBMS Figure 13-1: JDBC operation model In Figure 13-1 , the JDBC engine submits SQL query statements to the remote SQL processing engine (part of the RDBMS, it typically handles multiple simultaneous connections via a connection manager), and the SQL processing engine returns the result of the query in a set of data called a result set . A result set is typically zero or more rows of data. Think of result sets as a temporarily created table. JDBC operations are designed to do the following: . Take the JDBC API calls and transform them into an SQL query . Submit that query to the SQL processing engine on the RDBMS . Retrieve the result set that is returned from the query and transform it into a Java-accessible data structure Not all statements return a result set. If a search is not successful, the returned result set will be empty (called a NULL result set). In addition, the SQL language includes statements that are used to create tables, update data, delete rows, and so on; these statements do not return any result sets either.
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