检查MySQL中的JSON值是否为空？

     +------------+--------------------+-------+
     | id | name               | secondary_pitch |
     +------------+--------------------+-------+
     | 13 | Chris Sale         | ['Curveball','Slider'] |
     | 14 | Justin Verlander   | ['Fastball','Changeup'] |
     | 15 | CC Sabathia        | ['Fastball','Curveball'] |
     | 16 | Sonny Grey         |    ['Slider'] |
     | 17 | Aldoris Chapman    |    [] |
     +------------+--------------------+-------+

请注意,secondary_pitch列具有JSON值.因此,如果像Chapman这样的投手没有辅助音高,它将不会返回null,而是返回一个空的JSON字符串(‘[]’).

那么如何计算没有二级投手的投手数量呢？

我做不到……

  select count(*) from pitchers where secondary_pitch is null

SELECT count(*) from pitchers WHERE secondary_pitch IS NULL OR secondary_pitch = '';

你也可以像这样使用.

SELECT count(*) from pitchers WHERE secondary_pitch LIKE '%[]%'