Java, JDBC and MariaDB Types
MySQL Connector/J is flexible in the way it handles conversions between MariaDB data types and Java data types.
In general, any MariaDB data type can be converted to a java.lang.String, and any numeric type can be converted to any of the Java numeric types, although round-off, overflow, or loss of precision may occur.Note
All TEXT types return Types.LONGVARCHAR with different getPrecision() values (65535, 255, 16777215, and 2147483647 respectively) with getColumnType() returning -1. This behavior is intentional even though TINYTEXT does not fall, regarding to its size, within the LONGVARCHAR category. This is to avoid different handling inside the same base type. And getColumnType() returns -1 because the internal server handling is of type TEXT, which is similar to BLOB.
Also note that getColumnTypeName() will return VARCHAR even though getColumnType() returns Types.LONGVARCHAR, because VARCHAR is the designated column database-specific name for this type.
Starting with Connector/J 3.1.0, the JDBC driver issues warnings or throws DataTruncation exceptions as is required by the JDBC specification unless the connection was configured not to do so by using the property jdbcCompliantTruncation and setting it to false.
The conversions that are always guaranteed to work are listed in the following table:
Connection Properties - Miscellaneous.
| These MariaDB Data Types | Can always be converted to these Java types |
|---|---|
CHAR, VARCHAR, BLOB, TEXT, ENUM, and SET
| java.lang.String, java.io.InputStream, java.io.Reader, java.sql.Blob, java.sql.Clob
|
FLOAT, REAL, DOUBLE PRECISION, NUMERIC, DECIMAL, TINYINT, SMALLINT, MEDIUMINT, INTEGER, BIGINT
| java.lang.String, java.lang.Short, java.lang.Integer, java.lang.Long, java.lang.Double, java.math.BigDecimal
|
DATE, TIME, DATETIME, TIMESTAMP
| java.lang.String, java.sql.Date, java.sql.Timestamp |
Round-off, overflow or loss of precision may occur if you choose a Java numeric data type that has less precision or capacity than the MariaDB data type you are converting to/from.
The ResultSet.getObject() method uses the type conversions between MariaDB and Java types, following the JDBC specification where appropriate. The value returned by ResultSetMetaData.GetColumnClassName() is also shown below. For more information on the java.sql.Types classes see Java 2 Platform Types.
MySQL Types to Java Types for ResultSet.getObject().
| MySQL Type Name | Return value of GetColumnClassName
| Returned as Java Class |
|---|---|---|
| BIT(1) (new in MySQL-5.0) | BIT | java.lang.Boolean
|
| BIT( > 1) (new in MySQL-5.0) | BIT | byte[]
|
| TINYINT | TINYINT | java.lang.Boolean if the configuration property tinyInt1isBit is set to true (the default) and the storage size is 1, or java.lang.Integer if not.
|
| BOOL, BOOLEAN | TINYINT | See TINYINT, above as these are aliases for TINYINT(1), currently. |
| SMALLINT[(M)] [UNSIGNED] | SMALLINT [UNSIGNED] | java.lang.Integer (regardless if UNSIGNED or not)
|
| MEDIUMINT[(M)] [UNSIGNED] | MEDIUMINT [UNSIGNED] | java.lang.Integer, if UNSIGNED java.lang.Long (C/J 3.1 and earlier), or java.lang.Integer for C/J 5.0 and later
|
| INT,INTEGER[(M)] [UNSIGNED] | INTEGER [UNSIGNED] | java.lang.Integer, if UNSIGNED java.lang.Long
|
| BIGINT[(M)] [UNSIGNED] | BIGINT [UNSIGNED] | java.lang.Long, if UNSIGNED java.math.BigInteger
|
| FLOAT[(M,D)] | FLOAT | java.lang.Float
|
| DOUBLE[(M,B)] | DOUBLE | java.lang.Double
|
| DECIMAL[(M[,D])] | DECIMAL | java.math.BigDecimal
|
| DATE | DATE | java.sql.Date
|
| DATETIME | DATETIME | java.sql.Timestamp
|
| TIMESTAMP[(M)] | TIMESTAMP | java.sql.Timestamp
|
| TIME | TIME | java.sql.Time
|
| YEAR[(2|4)] | YEAR | If yearIsDateType configuration property is set to false, then the returned object type is java.sql.Short. If set to true (the default), then the returned object is of type java.sql.Date with the date set to January 1st, at midnight.
|
| CHAR(M) | CHAR | java.lang.String (unless the character set for the column is BINARY, then byte[] is returned.
|
| VARCHAR(M) [BINARY] | VARCHAR | java.lang.String (unless the character set for the column is BINARY, then byte[] is returned.
|
| BINARY(M) | BINARY | byte[]
|
| VARBINARY(M) | VARBINARY | byte[]
|
| TINYBLOB | TINYBLOB | byte[]
|
| TINYTEXT | VARCHAR | java.lang.String
|
| BLOB | BLOB | byte[]
|
| TEXT | VARCHAR | java.lang.String
|
| MEDIUMBLOB | MEDIUMBLOB | byte[]
|
| MEDIUMTEXT | VARCHAR | java.lang.String
|
| LONGBLOB | LONGBLOB | byte[]
|
| LONGTEXT | VARCHAR | java.lang.String
|
| ENUM('value1','value2',...) | CHAR | java.lang.String
|
| SET('value1','value2',...) | CHAR | java.lang.String |