Java与MySQL数据类型对照，让你的数据库设计更高效！

在Java和MySQL之间进行数据交互时，了解两者的数据类型对照是非常重要的。这不仅有助于确保数据的准确存储和检索，还能提高应用程序的性能和可靠性。以下是Java和MySQL中常见数据类型的对照表及其详解：

整数类型

1. Java byte 对应 MySQL TINYINT

   • Java: 8-bit signed integer (-128 to 127)
   • MySQL: 1-byte signed integer (-128 to 127)

2. Java short 对应 MySQL SMALLINT

   • Java: 16-bit signed integer (-32,768 to 32,767)
   • MySQL: 2-byte signed integer (-32,768 to 32,767)

3. Java int 对应 MySQL INT

   • Java: 32-bit signed integer (-2^31 to 2^31-1)
   • MySQL: 4-byte signed integer (-2^31 to 2^31-1)

4. Java long 对应 MySQL BIGINT

   • Java: 64-bit signed integer (-2^63 to 2^63-1)
   • MySQL: 8-byte signed integer (-2^63 to 2^63-1)

浮点类型

1. Java float 对应 MySQL FLOAT

   • Java: 32-bit single precision floating point
   • MySQL: Single precision floating point

2. Java double 对应 MySQL DOUBLE

   • Java: 64-bit double precision floating point
   • MySQL: Double precision floating point

定点数类型

1. Java BigDecimal 对应 MySQL DECIMAL
   • Java: Immutable, arbitrary-precision signed decimal numbers
   • MySQL: Fixed precision floating point number

字符串类型

1. Java String 对应 MySQL CHAR, VARCHAR

   • Java: Variable length string
   • MySQL:
     • CHAR(n): Fixed length string of exactly n characters
     • VARCHAR(n): Variable length string with a maximum length of n characters

2. Java char 对应 MySQL CHAR(1)

   • Java: 16-bit Unicode character
   • MySQL: 1-character fixed length string

日期和时间类型

1. Java java.sql.Date 对应 MySQL DATE

   • Java: Represents date without time of day and timezone
   • MySQL: Date only value

2. Java java.sql.Time 对应 MySQL TIME

   • Java: Represents time without date and timezone
   • MySQL: Time only value

3. Java java.sql.Timestamp 对应 MySQL DATETIME

   • Java: Represents date and time with nanosecond precision and timezone
   • MySQL: Date and time value with microsecond precision (no timezone)

4. Java LocalDate 对应 MySQL DATE

   • Java: Represents a date without time of day or timezone
   • MySQL: Date only value

5. Java LocalTime 对应 MySQL TIME

   • Java: Represents a time without date or timezone
   • MySQL: Time only value

6. Java LocalDateTime 对应 MySQL DATETIME

   • Java: Represents date and time without timezone
   • MySQL: Date and time value without timezone

7. Java OffsetDateTime 对应 MySQL DATETIME + TIME ZONE information

   • Java: Represents date and time with timezone information
   • MySQL: Date and time value stored as DATETIME with separate column for timezone information if needed

布尔类型

1. Java boolean 对应 MySQL BOOLEAN 或 TINYINT(1)
   • Java: True or false value
   • MySQL:
     • BOOLEAN: True or false value
     • TINYINT(1): Typically used for boolean values in older versions of MySQL, where 0 represents false and non-zero represents true

其他类型

1. Java java.sql.Blob 对应 MySQL BLOB

   • Java: Binary large object
   • MySQL: Large binary object

2. Java java.sql.Clob 对应 MySQL TEXT

   • Java: Character large object
   • MySQL: Large text object

总结

以上是Java和MySQL中常见数据类型的对照表及其详解。在实际开发中，选择合适的数据类型对于保证数据的一致性和性能至关重要。例如，使用VARCHAR而不是CHAR可以节省存储空间，但可能会影响查询性能；使用BIGINT而不是INT可以处理更大的数值范围等。理解这些数据类型之间的对应关系可以帮助开发者更好地设计和优化数据库结构。