from m_tb
left join
(
select id, title, mid, max(times) as 最近时间
from m_vs
group by mid
) on (m_tb.id=m_vs.mid)
题主你好,
使用regexp_replace函数替代replace函数即可实现.
代码及测试截图如下:
*.测试是的是我自己的表,按照你问题中的参数来说, 将语句改为:
update ab set name=regexp_replace(cd, '^t', 'T')
-----
希望可以帮到题主, 欢迎追问.
select id,name,coalesce((select id from table1 where name=left(tt2.name,1)),-1) nameID1,
coalesce((select id from table1 where name=mid(tt2.name,3,1)),-1) nameID2,
coalesce((select id from table1 where name=mid(tt2.name,5,1)),-1) nameID3,
coalesce((select id from table1 where name=mid(tt2.name,7,1)),-1) nameID4
from table2
如果保证table2.name中无空格且table1.name长度都为1,那以下也可以用
select table2.id,table2.name,max(case when instr(table2.name,table1.name)=1 then table1.id else -1 end) naemID1,
max(case when instr(table2.name,table1.name)=3 then table1.id else -1 end) naemID2,
max(case when instr(table2.name,table1.name)=5 then table1.id else -1 end) naemID3,
max(case when instr(table2.name,table1.name)=7 then table1.id else -1 end) naemID4
from table2 left join tt1 on instr(table2.name, table1.name)>0
group by table2.id, table2.name
如果table2.name有空格或table1.name长度不都为1,也可以使用
select table2.id,table2.name,max(case when length(left(table2.name,instr(table2.name, table1.name)))-length(replace(left(table2.name,instr(table2.name,table1.name)), ',', ''))=0
then table1.id else -1 end) naemID1,
max(case when length(left(table2.name,instr(table2.name, table1.name)))-length(replace(left(table2.name,instr(table2.name,table1.name)), ',', ''))=1
then table1.id else -1 end) naemID2,
max(case when length(left(table2.name,instr(table2.name, table1.name)))-length(replace(left(table2.name,instr(table2.name,table1.name)), ',', ''))=2
then table1.id else -1 end) naemID3,
max(case when length(left(table2.name,instr(table2.name, table1.name)))-length(replace(left(table2.name,instr(table2.name,table1.name)), ',', ''))=3
then table1.id else -1 end) naemID4
from table2 left join table1 on instr(table2.name, table1.name)>0
group by table2.id, table2.name
length(left(table2.name,instr(table2.name, table1.name)))-length(replace(left(table2.name,instr(table2.name,table1.name)), ',', ''))这个表达式是找到相应的table1.name前面的逗号个数即对应table1.name的位置
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