1、整型    tinyint 2^7        -128 ~128-1        0 ~ 256-1
    smallint 2^15        -32768 ~ 32768-1        0 ~ 65536-1
    mediumint 2^23        -8388608 ~ 8388608-1        0 ~ 16777216
    int 2^31        -2147483648 ~ 2147483648-1        0 ~ 4294967296
    bigint 2^63        -9223372036854776000 ~ 9223372036854776000-1        0 ~ 18446744073709552000

2、浮点型(m是数字总位数，d是小数点后位数)    float[(m, d)]
    double[(m, d)]

3、字符型    char(m)    0 ~ 255
    varchar()    0 ~ 65535+1
    tinytext     0 ~ 256+1
           text        0 ~ 65536+2
         mediumtext    0 ~ 16777216+3 
      longtext    0 ~ 4294967296+4
        enum("value1", "value2", "value_3")
        set("value1", “value2", "value_3") 

*unsigned修饰数据类型后，将从0开始