Whenever you want to modify the values of a table, you can use the UPDATE command. This will modify any field value from any HSQLDB table.
Syntax
Here is the generic syntax for the UPDATE command.
UPDATE table_name SET field1 = new-value1, field2 = new-value2 [WHERE Clause]
- You can update one or more field altogether.
- You can specify any condition using WHERE clause.
- You can update values in a single table at a time.
Example
Let us consider an example that updates the title of the tutorial from “Learn C” to “C and Data Structures” having an id “101”. Following is the query for the update.
UPDATE tutorials_tbl SET title = 'C and Data Structures' WHERE id = 101;
After execution of the above query, you will receive the following output.
(1) Rows effected
HSQLDB – JDBC Program
Here is the JDBC program that will update a tutorial title from Learn C to C and Data Structures having an id 101. Save the following program into the UpdateQuery.java file.
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;
public class UpdateQuery {
public static void main(String[] args) {
Connection con = null;
Statement stmt = null;
int result = 0;
try {
Class.forName("org.hsqldb.jdbc.JDBCDriver");
con = DriverManager.getConnection(
"jdbc:hsqldb:hsql://localhost/testdb", "SA", "");
stmt = con.createStatement();
result = stmt.executeUpdate(
"UPDATE tutorials_tbl SET title = 'C and Data Structures' WHERE id = 101");
} catch (Exception e) {
e.printStackTrace(System.out);
}
System.out.println(result+" Rows effected");
}
}
You can start the database using the following command.
\>cd C:\hsqldb-2.3.4\hsqldb
hsqldb>java -classpath lib/hsqldb.jar org.hsqldb.server.Server --database.0
file:hsqldb/demodb --dbname.0 testdb
Compile and execute the above program using the following command.
\>javac UpdateQuery.java
\>java UpdateQuery
After execution of the above command, you will receive the following output −
1 Rows effected
