MySQL 查询删除字符串中最后一个逗号后的所有字符?
mysqlmysqli database
要删除字符串中最后一个逗号后的所有字符，可以使用 SUBSTRING_INDEX()。
如果您不知道最后一个逗号的位置，则需要使用 LENGTH() 动态查找最后一个逗号。
语法如下 −
UPDATE yourTableName set yourColumnName = SUBSTRING_INDEX(yourColumnName, ',', LENGTH(yourColumnName) - LENGTH(REPLACE(yourColumnName, ',', '')));
为了理解上述语法，让我们创建一个表。创建表的查询如下 −
mysql> create table RemoveAllCharacters -> ( -> Id int NOT NULL AUTO_INCREMENT, -> FullInfo varchar(200), -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (1.83 sec)
使用 insert 命令在表中插入一些记录。 查询语句如下 −
mysql> insert into RemoveAllCharacters(FullInfo) values('John,Smith,23,98,4565886');
Query OK, 1 row affected (0.23 sec)
mysql> insert into RemoveAllCharacters(FullInfo) values('Carol,Taylor,26,91');
Query OK, 1 row affected (0.28 sec)
mysql> insert into RemoveAllCharacters(FullInfo) values('David,Miller,21');
Query OK, 1 row affected (0.11 sec)
mysql> insert into RemoveAllCharacters(FullInfo) values('Robert,Jones,22,97');
Query OK, 1 row affected (0.09 sec)
mysql> insert into RemoveAllCharacters(FullInfo)
values('Sam,Williams,27,88,456788,97877');
Query OK, 1 row affected (0.13 sec)
使用 select 语句显示表中的所有记录。查询如下 −
mysql> select *from RemoveAllCharacters;
以下是输出 −
+----+---------------------------------+ | Id | FullInfo | +----+---------------------------------+ | 1 | John,Smith,23,98,4565886 | | 2 | Carol,Taylor,26,91 | | 3 | David,Miller,21 | | 4 | Robert,Jones,22,97 | | 5 | Sam,Williams,27,88,456788,97877 | +----+---------------------------------+ 5 rows in set (0.00 sec)
以下是删除字符串中最后一个逗号后所有字符的查询 −
mysql> update RemoveAllCharacters -> set FullInfo = SUBSTRING_INDEX(FullInfo, ',', LENGTH(FullInfo) - LENGTH(REPLACE(FullInfo, ',', ''))); Query OK, 5 rows affected (0.28 sec) Rows matched: 5 Changed: 5 Warnings: 0
现在再次检查表中的所有记录。查询如下 −
mysql> select *from RemoveAllCharacters;
以下是显示没有最后一个逗号后字符的记录的输出:
+----+---------------------------+ | Id | FullInfo | +----+---------------------------+ | 1 | John,Smith,23,98 | | 2 | Carol,Taylor,26 | | 3 | David,Miller | | 4 | Robert,Jones,22 | | 5 | Sam,Williams,27,88,456788 | +----+---------------------------+ 5 rows in set (0.00 sec)
