问题:
sql 中的下划线如何改变其含义
select * from ctn where a like 'C_'
返回列a以C开头,长度为2的记录
select * from ctn where a like 'C__'
返回列a以C开头,长度为3的记录
但如何实现a列以C_开头的记录(一般意义的like)?
select * from ctn where a like 'C_%' 无发实现
解决办法:
SQL> select id from test where id like 'c=_%' escape '=';
ID
------------------------------------------------------------
c_zhang
SQL> select id from test where id like 'c/_%' escape '/';
ID
------------------------------------------------------------
c_zhang
关键字: escape