MySQL | Kode Java - Learn Java by Examples

How do I get numeric functions supported by database?

By Wayan in JDBC Last modified: July 31, 2023 0 Comment

package org.kodejava.jdbc;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.DatabaseMetaData;
import java.sql.SQLException;

public class NumericFunction {
    private static final String URL = "jdbc:mysql://localhost/kodejava";
    private static final String USERNAME = "kodejava";
    private static final String PASSWORD = "s3cr*t";

    public static void main(String[] args) {
        try (Connection connection =
                     DriverManager.getConnection(URL, USERNAME, PASSWORD)) {
            DatabaseMetaData meta = connection.getMetaData();

            // Get numeric functions supported by database
            String[] functions = meta.getNumericFunctions().split(",\\s*");

            for (String function : functions) {
                System.out.println("Function = " + function);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

Here are the numeric functions supported by MySQL database.

Function = ABS
Function = ACOS
Function = ASIN
Function = ATAN
Function = ATAN2
Function = BIT_COUNT
Function = CEILING
Function = COS
Function = COT
Function = DEGREES
Function = EXP
Function = FLOOR
Function = LOG
Function = LOG10
Function = MAX
Function = MIN
Function = MOD
Function = PI
Function = POW
Function = POWER
Function = RADIANS
Function = RAND
Function = ROUND
Function = SIN
Function = SQRT
Function = TAN
Function = TRUNCATE

Maven Dependencies

<dependency>
    <groupId>com.mysql</groupId>
    <artifactId>mysql-connector-j</artifactId>
    <version>8.1.0</version>
</dependency>

How do I get string functions supported by database?

By Wayan in JDBC Last modified: July 31, 2023 0 Comment

package org.kodejava.jdbc;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.DatabaseMetaData;
import java.sql.SQLException;

public class StringFunction {
    private static final String URL = "jdbc:mysql://localhost/kodejava";
    private static final String USERNAME = "kodejava";
    private static final String PASSWORD = "s3cr*t";

    public static void main(String[] args) {
        try (Connection connection =
                     DriverManager.getConnection(URL, USERNAME, PASSWORD)) {
            DatabaseMetaData meta = connection.getMetaData();

            // Get string functions supported by database
            String[] functions = meta.getStringFunctions().split(",\\s*");

            for (String function : functions) {
                System.out.println("Function = " + function);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

Here are the string functions supported by MySQL database:

Function = ASCII
Function = BIN
Function = BIT_LENGTH
Function = CHAR
Function = CHARACTER_LENGTH
Function = CHAR_LENGTH
Function = CONCAT
Function = CONCAT_WS
Function = CONV
Function = ELT
Function = EXPORT_SET
Function = FIELD
Function = FIND_IN_SET
Function = HEX
Function = INSERT
Function = INSTR
Function = LCASE
Function = LEFT
Function = LENGTH
Function = LOAD_FILE
Function = LOCATE
Function = LOCATE
Function = LOWER
Function = LPAD
Function = LTRIM
Function = MAKE_SET
Function = MATCH
Function = MID
Function = OCT
Function = OCTET_LENGTH
Function = ORD
Function = POSITION
Function = QUOTE
Function = REPEAT
Function = REPLACE
Function = REVERSE
Function = RIGHT
Function = RPAD
Function = RTRIM
Function = SOUNDEX
Function = SPACE
Function = STRCMP
Function = SUBSTRING
Function = SUBSTRING
Function = SUBSTRING
Function = SUBSTRING
Function = SUBSTRING_INDEX
Function = TRIM
Function = UCASE
Function = UPPER

Maven Dependencies

<dependency>
    <groupId>com.mysql</groupId>
    <artifactId>mysql-connector-j</artifactId>
    <version>8.1.0</version>
</dependency>

How do to commit or rollback transaction in JDBC?

By Wayan in JDBC Last modified: July 24, 2023 0 Comment

Executing a database manipulation command such as insert, update or delete can sometime throw exception due to invalid data. To protect the integrity of our application data we must make sure that when a transaction fails we must rollback all the executed queries.

In this example we are using MySQL database. To enable transaction capability in MySQL make sure that you are using InnoDB storage engine to create your databases and tables.

package org.kodejava.jdbc;

import java.math.BigDecimal;
import java.sql.*;

public class TransactionRollbackExample {
    private static final String URL = "jdbc:mysql://localhost/kodejava";
    private static final String USERNAME = "kodejava";
    private static final String PASSWORD = "s3cr*t";

    public static void main(String[] args) {
        try (Connection conn =
                     DriverManager.getConnection(URL, USERNAME, PASSWORD)) {
            conn.setAutoCommit(false);

            String orderQuery = """
                    INSERT INTO purchase_order (username, order_date)
                    VALUES (?, ?)
                    """;

            try (PreparedStatement stmt = conn.prepareStatement(orderQuery,
                    PreparedStatement.RETURN_GENERATED_KEYS)) {
                stmt.setString(1, "jduke");
                stmt.setDate(2, new Date(System.currentTimeMillis()));
                stmt.execute();

                ResultSet keys = stmt.getGeneratedKeys();
                long orderId = 1L;
                if (keys.next()) {
                    orderId = keys.getLong(1);
                }

                // This is an invalid statement that will cause exception to
                // demonstrate a rollback.
                String orderDetailQuery = """
                        INSERT INTO purchase_order_detail (order_id, product_id, quantity, price)
                        VALUES (?, ?, ?, ?)
                        """;

                PreparedStatement detailStmt = conn.prepareStatement(orderDetailQuery);
                detailStmt.setLong(1, orderId);
                detailStmt.setInt(2, 1);
                detailStmt.setInt(3, 10);
                detailStmt.setBigDecimal(4, new BigDecimal("29.99"));
                detailStmt.execute();

                // Commit transaction to mark it as a success database operation
                conn.commit();
                System.out.println("Transaction commit...");
            } catch (SQLException e) {
                // Rollback any database transaction due to exception occurred
                conn.rollback();
                System.out.println("Transaction rollback...");
                e.printStackTrace();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Maven Dependencies

<dependency>
    <groupId>com.mysql</groupId>
    <artifactId>mysql-connector-j</artifactId>
    <version>8.1.0</version>
</dependency>

How do I get all table names from a database?

By Wayan in JDBC Last modified: July 24, 2023 0 Comment

package org.kodejava.jdbc;

import java.sql.*;

public class GettingTableListExample {
    private static final String URL = "jdbc:mysql://localhost/kodejava";
    private static final String USERNAME = "kodejava";
    private static final String PASSWORD = "s3cr*t";

    public static void main(String[] args) {
        try (Connection connection =
                     DriverManager.getConnection(URL, USERNAME, PASSWORD)) {

            // Gets the metadata of the database
            DatabaseMetaData metaData = connection.getMetaData();
            String[] types = {"TABLE"};

            ResultSet rs = metaData.getTables("kodejava", "kodejava", "%", types);
            while (rs.next()) {
                String tableCatalog = rs.getString(1);
                String tableSchema = rs.getString(2);
                String tableName = rs.getString(3);

                System.out.printf("%s - %s - %s%n",
                        tableCatalog, tableSchema, tableName);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Here is the result:

kodejava - null - author
kodejava - null - book_author
kodejava - null - book

Maven Dependencies

<dependency>
    <groupId>com.mysql</groupId>
    <artifactId>mysql-connector-j</artifactId>
    <version>8.1.0</version>
</dependency>

How do I drop table from a database?

By Wayan in JDBC Last modified: July 24, 2023 0 Comment

This example is to show you how to delete or drop a table from your database. Basically we just send a DROP TABLE command and specify the table name to be deleted to the database. The example below show you how to do it in MySQL database.

package org.kodejava.jdbc;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;

public class DropTableExample {
    private static final String URL = "jdbc:mysql://localhost/kodejava";
    private static final String USERNAME = "kodejava";
    private static final String PASSWORD = "s3cr*t";

    public static void main(String[] args) {
        try (Connection connection =
                     DriverManager.getConnection(URL, USERNAME, PASSWORD)) {

            // To delete a table from database we use the DROP TABLE
            // command and specify the table name to be dropped
            String sql = "DROP TABLE IF EXISTS book";

            // Create a statement
            Statement statement = connection.createStatement();
            // Execute the statement to delete the table
            statement.execute(sql);
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

Maven Dependencies

<dependency>
    <groupId>com.mysql</groupId>
    <artifactId>mysql-connector-j</artifactId>
    <version>8.1.0</version>
</dependency>