Question

我正在尝试查询“标签”列中的所有唯一值。标签列中的每一行都可以包含多个值。因此，如果不强制进入规范化，我如何查询多值列？

示例行：

Networking
Professionalism
Time Management
Communication, Networking
Career Management, Professionalism
Networking
Communication
Attitude, Interpersonal Skills, Professionalism
Business Protocol, Career Management, Communication, Leadership
Business Protocol, Networking

Answer 1

如果元素的最大数量是可预测的，您可以使用此功能（请注意，您需要使用UNION，而不是UNION ALL）

Select DISTINCT thefield from thetable where Instr(thefield, ',') = 0
UNION 
Select Distinct Mid(thefield, 1, Instr(thefield, ',')) from thetable Where len(thefield) - len(replace(thefield,',','')) = 1
UNION 
Select Distinct Mid(thefield, Instr(thefield, ',')+1) from thetable Where len(thefield) - len(replace(thefield,',','')) = 1
UNION 
Select Distinct Mid(thefield, Instr(thefield, ',')+1, Instr(Instr(thefield, ',')+1,thefield, ',')) from thetable Where len(thefield) - len(replace(thefield,',','')) = 2
UNION 
Select Distinct Mid(thefield, Instr(Instr(thefield, ',')+1,thefield, ',')+1) from thetable Where len(thefield) - len(replace(thefield,',','')) = 2
--.. and so on (repeat last two Selects as many time as you wish, increasing the where condition by one for each pair)

看起来有点笨重，但应该做的工作。未经测试，因此，您可能会在值

之前或之后出现迷路逗号

从多值列中查询不同的值

1 个答案: