在SQL中如何获取整数的最大值？

是否有任何内置的常量或函数我可以使用(标准SQL或MySQL具体).

在http://dev.mysql.com/doc/refman/5.0/en/numeric-types.html它列出了值 – 但是有一种数据库告诉我的方法.

以下给出了MAX_BIGINT – 我想要的是MAX_INT.

SELECT CAST( 99999999999999999999999 AS SIGNED ) as max_int;
# max_int | 9223372036854775807

提前致谢,

解决方法

mysql> select ~0;
+----------------------+
| ~0                   |
+----------------------+
| 18446744073709551615 |
+----------------------+

波浪号是逐位否定.得到的值是一个bigint.见：http://dev.mysql.com/doc/refman/5.1/en/bit-functions.html#operator_bitwise-invert

对于其他整数风格,您可以使用正确的位移操作符>>像这样：

SELECT ~0 as max_bigint_unsigned,~0 >> 32 as max_int_unsigned,~0 >> 40 as max_mediumint_unsigned,~0 >> 48 as max_smallint_unsigned,~0 >> 56 as max_tinyint_unsigned,~0 >> 1  as max_bigint_signed,~0 >> 33 as max_int_signed,~0 >> 41 as max_mediumint_signed,~0 >> 49 as max_smallint_signed,~0 >> 57 as max_tinyint_signed
G

*************************** 1. row ***************************
   max_bigint_unsigned: 18446744073709551615
      max_int_unsigned: 4294967295
max_mediumint_unsigned: 16777215
 max_smallint_unsigned: 65535
  max_tinyint_unsigned: 255
     max_bigint_signed: 9223372036854775807
        max_int_signed: 2147483647
  max_mediumint_signed: 8388607
   max_smallint_signed: 32767
    max_tinyint_signed: 127
1 row in set (0.00 sec)

（编辑：李大同）

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