在MySQL中仅使用会话变量仅对字符的首次出现执行搜索/替换
要仅对首次出现的位置执行搜索/替换，请使用CONCAT和REPLACE()方法。
查询如下以设置用户定义的会话变量-
mysql> set @Sentence='Thks ks is a my string';
在此，k将仅被i替换一次。查询如下。我们还使用了INSTR()-
mysql> select @Sentence as NewString ,CONCAT(REPLACE(LEFT(@Sentence, INSTR(@Sentence, 'k')), 'k', 'i'), -> SUBSTRING(@Sentence, INSTR(@Sentence, 'k') + 1)) as ChangeOnlyOneTime;
以下是仅显示首次出现的字符被替换的输出-
+------------------------+------------------------+ | NewString | ChangeOnlyOneTime | +------------------------+------------------------+ | Thks ks is a my string | This ks is a my string | +------------------------+------------------------+ 1 row in set (0.00 sec)