MySQL SIGN 函数

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  定义和用法

  SIGN - 返回数字的符号。
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  语法

  SIGN(X)

  返回X的符号（负数-1为或零或正为1）。
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  示例

  mysql>SELECT SIGN(-4.65);
  +---------------------------------------------------------+
  |                      SIGN(-4.65)                        |
  +---------------------------------------------------------+
  |                          -1                             |
  +---------------------------------------------------------+
  1 row in set (0.00 sec)
  
  mysql>SELECT SIGN(0);
  +---------------------------------------------------------+
  |                         SIGN(0)                         |
  +---------------------------------------------------------+
  |                            0                            |
  +---------------------------------------------------------+
  1 row in set (0.00 sec)
  
  mysql>SELECT SIGN(4.65);
  +---------------------------------------------------------+
  |                         SIGN(4.65)                      |
  +---------------------------------------------------------+
  |                             1                           |
  +---------------------------------------------------------+
  1 row in set (0.00 sec)
  

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