根据分隔符“|”将一列分成三列

Question

我有一个表

id methods 
1 a|b|c 
2 e|f|g 

我怎样才能改变表

id method1 method2 method3 
1 a  b  c 
2 e  f  g 

Answer 1

不知道你所使用的RDBMS，但我得到这个在SQL Server，MySQL和SQLite的工作。这使得假设只有三个项目需要从字符串中拆分出来

重申@Joel Coehoorn提到的内容。给出大量数据时，这可能非常缓慢。最好是改变表的模式，并具有数据分离之前在表

SQL Server版本

select t.id, t.methods, 
SUBSTRING(t.methods, 1, CHARINDEX('|', t.methods)-1) as method1, 
SUBSTRING(t.methods, CHARINDEX('|', t.methods)+1, CHARINDEX('|', t.methods, CHARINDEX('|', t.methods)+1)-CHARINDEX('|', t.methods)-1) as method2, 
SUBSTRING(t.methods, CHARINDEX('|', t.methods, CHARINDEX('|', t.methods)+1)+1,len(t.methods)) as method3 
from TestTable t 

MySQL版本

select t.id, t.methods, 
SUBSTRING(t.methods, 1, LOCATE('|', t.methods)-1) as method1, 
SUBSTRING(t.methods, LOCATE('|', t.methods)+1, LOCATE('|', t.methods, LOCATE('|', t.methods)+1)-LOCATE('|', t.methods)-1) as method2, 
SUBSTRING(t.methods, LOCATE('|', t.methods, LOCATE('|', t.methods)+1)+1) as method3 
from TestTable t 

不断插入SQLite

select 
SUBSTR(t.methods, 1, INSTR(t.methods, '|')-1) as method1, 
SUBSTR(t.methods, INSTR(t.methods, '|')+1, INSTR(SUBSTR(t.methods, INSTR(t.methods, '|')+1), '|')-1) as method2, 
SUBSTR(t.methods, INSTR(SUBSTR(t.methods, INSTR(t.methods, '|')+1), '|')+ INSTR(t.methods, '|')+1) as method3 
from TestTable t