Question

我有这个问题：

SELECT AVG(value), EXTRACT(YEAR FROM date_input)::text || EXTRACT(MONTH FROM date_input)::text AS tgl FROM app_inputdata WHERE dataid='95' AND date_input BETWEEN '2013-01-01' AND '2016-12-31' GROUP BY tgl ORDER BY tgl

，此查询的结果如下：

+-----+--------+
| avg | tgl    |
+-----+--------+
|23.1 | 20141  |
|12.1 | 201412 | 
|1.7  | 20142  |
+-----+--------+

如您所见，tgl 201412出现在第二行，它应出现在最后一行。我在想它是因为tgl是字符串类型，那么如何将其排序为整数？

Answer 1

尝试使用日期组件：

SELECT AVG(value),
       EXTRACT(YEAR FROM date_input)::text || EXTRACT(MONTH FROM date_input)::text AS tgl
FROM app_inputdata
WHERE dataid='95' AND
      date_input BETWEEN '2013-01-01' AND '2016-12-31'
GROUP BY tgl
ORDER BY MAX(EXTRACT(YEAR FROM date_input)), MAX(EXTRACT(MONTH FROM date_input))

postgresql将数字字符串作为整数

1 个答案: