Managing MySQL Datetimes and Timestamps in Java

When working with a MySQL database from a Java application, handling date and time information can be a challenge due to the different data types available. To find a suitable compromise, it's important to understand the characteristics of each type.

Representation in Java

In Java, dates are typically represented by the java.util.Date class. This class encapsulates a timestamp, which contains both date and time information. The precision of java.util.Date is typically in milliseconds.

Representation in MySQL

MySQL offers three standard date and time types: DATE, TIME, and TIMESTAMP. In JDBC, these types are mapped to java.sql.Date, java.sql.Time, and java.sql.Timestamp, respectively. These classes are subclasses of java.util.Date.

Unlike java.util.Date, java.sql.Date only contains date information, while java.sql.Time only contains time information. java.sql.Timestamp, on the other hand, combines both date and time information. The precision of these types depends on the database, but it is often in milliseconds.

Storing Timestamps

To store a timestamp in the database, you can use PreparedStatement#setTimestamp() method.

java.util.Date date = getItSomehow();
Timestamp timestamp = new Timestamp(date.getTime());
preparedStatement = connection.prepareStatement("SELECT * FROM tbl WHERE ts > ?");
preparedStatement.setTimestamp(1, timestamp);

Retrieving Timestamps

To retrieve a timestamp from the database, you can use ResultSet#getTimestamp() method.

Timestamp timestamp = resultSet.getTimestamp("ts");
java.util.Date date = timestamp; // You can just upcast.

By understanding these different data types and their usage patterns, you can effectively manage datetimes and timestamps in your Java application when interfacing with a MySQL database.