Advanced Database Persistence for Java

Examples & Reference Manual
 

MySQL

The HotRod MySQL adapter automatically maps known database column types to DAO Java types. In most of the cases this default Java type is well suited to handle the database values. However, when needed the default Java type of a property can be overridden by a custom type if it's provided by the developer.

Default Java Types

If a custom Java type is not specified HotRod will use the following rules to decide which Java type to use for each MySQL column. In yellow is the DAO property type. In parenthesis the actual object type returned by the MySQL JDBC driver, that on occasions may be different.

Please note that the Java types for the MySQL columns may vary depending on the specific version and variant of the RDBMS, the operating system where the database engine is running, and the JDBC driver version.

MySQL Column Type Default Java Type
TINYINT,
INT1 		java.lang.Byte
TINYINT UNSIGNED,
INT1 UNSIGNED 		java.lang.Short
SMALLINT,
INT2 		java.lang.Short
SMALLINT UNSIGNED,
INT2 UNSIGNED 		java.lang.Integer
MEDIUMINT,
INT3 		java.lang.Integer
MEDIUMINT UNSIGNED,
INT3 UNSIGNED 		java.lang.Integer
INTEGER,
INT4 		java.lang.Integer
INTEGER UNSIGNED,
INT4 UNSIGNED 		java.lang.Long
BIGINT,
INT8 		java.lang.Long
BIGINT UNSIGNED,
INT8 UNSIGNED 		java.math.BigInteger
DECIMAL(p,s),
NUMERIC(p,s) 		If neither p or s are specified:
  • java.lang.Long
If s is specified and different from zero the Java type is:
  • java.math.BigDecimal
if s is not specified or specified with a value of zero:
  • if p <= 2: java.lang.Byte
  • if 2 < p <= 4: java.lang.Short
  • if 4 < p <= 9: java.lang.Integer
  • if 9 < p <= 18: java.lang.Long
  • if p > 18: java.math.BigInteger
FLOAT(n),
FLOAT4(n),
FLOAT(n) UNSIGNED,
FLOAT4(n) UNSIGNED 		If n is not specified:
  • java.lang.Float
If n is specified:
  • if n <= 24: java.lang.Float
  • if n >= 25: java.lang.Double
DOUBLE,
DOUBLE PRECISION,
REAL,
FLOAT8,
DOUBLE UNSIGNED,
DOUBLE PRECISION UNSIGNED,
REAL UNSIGNED,
FLOAT8 UNSIGNED 		java.lang.Double
CHAR(n),
VARCHAR(n),
TINYTEXT,
TEXT,
MEDIUMTEXT,
LONGTEXT 		java.lang.String
DATE,
YEAR 		java.sql.Date
TIME java.sql.Time
DATETIME,
TIMESTAMP 		java.sql.Timestamp
TINYBLOB,
BLOB,
MEDIUMBLOB,
LONGBLOB 		byte[]
ENUM java.lang.String
SET java.lang.String

Custom Java Types

To override the default Java type see the reference section for the tables, views, and selects. The Example 19 - Custom DAO Property Java Types shows a case where a custom type overrides the default type. To override the default type add a <column> tag in a <table> , <view> , or <select> definition.