在SQL中选择/转换输出为整数

Question

我正在开发一个网站,要求我显示用户输入每天平均数量的图表.我已经有一个SQL查询,它会将此信息返回给我:

SELECT sum(number)/count(number) as average, date FROM stats WHERE * GROUP BY date

这给了我正在寻找的结果,但结果以三位小数精度给出.我想围绕这个数字.当然,我可以在PHP或我的模板引擎中完成它,但我很好奇是否有办法在数据库中完成所有这些操作.

有没有办法将输出转换为整数(在MySQL中)？

Answer 1

SELECT 
  CAST(sum(number)/count(number) as UNSIGNED) as average, 
  date 
FROM stats 
WHERE * 
GROUP BY date

Answer 2

CASTMySQL中的有效类型如下

• BINARY[(N)]
• CHAR[(N)]
• DATE
• DATETIME
• DECIMAL[(M[,D])]
• SIGNED [INTEGER]
• TIME
• UNSIGNED [INTEGER]

所以你可以使用

SELECT CAST(sum(number)/count(number) AS UNSIGNED) as average...

或者,SIGNED如果SUM零件可以加起来为负数.

Answer 3

如何使用MySQL FORMAT功能？

mysql> SELECT FORMAT(12345.123456, 4);
+-------------------------+
| FORMAT(12345.123456, 4) |
+-------------------------+
| 12,345.1235             |
+-------------------------+
1 row in set (0.00 sec)

mysql> SELECT FORMAT(12345.123456, 0);
+-------------------------+
| FORMAT(12345.123456, 0) |
+-------------------------+
| 12,345                  |
+-------------------------+
1 row in set (0.00 sec)

Answer 4

使用DIV运营商.

mysql> SELECT 5 DIV 2;
    -> 2

整数除法.与FLOOR()类似,但BIGINT值是安全的.对于超出BIGINT范围的非整数操作数,可能会出现不正确的结果.