- How to send
an SQL query to
the SQL server for
execution:
ResultSet rset; // Ref. var. to hold the result of the execution rset = SQLstatement.executeQuery("SQL-query"); ^^^^^^^^^^^^ ( returned by createStatement() ) (1) sends "SQL-query" to the server for execution (2) returns a ResultSet object (that contains the selected tuples)
ResultSet rset; // Ref. var. to hold the result of the execution rset = SQLstatement.executeQuery("select * from employee");Explanation:
- The string
"SQL-query"
contains an
SQL query
- The executeQuery( ) call
will:
- Send the
SQL-query
to the
SQL server for
processing
(It sends the message using the SQL connection)
- Receive the
result set from
the SQL server
- The ResultSet object contains the tuples of the select query
The result set can be accessed using the rset variable
- Send the
SQL-query
to the
SQL server for
processing
- The string
"SQL-query"
contains an
SQL query
- What is
achieved by the
SQLstatement.executeQuery( .... )
call:
- Before the
Java program
executes the
SQLstatement.executeQuery( .... )
statement:
- The
SQLstatement.executeQuery("select * from employee" )
first send
the query to the
SQL server:
- Then the client
will receive
the reply from the
SQL server:
- After the
Java program
executes the
SQLstatement.executeQuery("...")
statement:
Note:
- The result set object rset contains the result of the select query execution
- Before the
Java program
executes the
SQLstatement.executeQuery( .... )
statement: