22.3.5.3. Java, JDBC and MySQL Types

MySQL Connector/J is flexible in the way it handles conversions between MySQL data types and Java data types.

In general, any MySQL 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. The first column lists one or more MySQL data types, and the second column lists one or more Java types to which the MySQL types can be converted.

Table 22.24. Connection Properties - Miscellaneous

These MySQL 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`

Note

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 MySQL data type you are converting to/from.

The ResultSet.getObject() method uses the type conversions between MySQL 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.

Table 22.25. 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`