MySQL 如何获取最长VarChar长度

要获得最长的varchar长度，您需要使用CHAR_LENGTH()。

语法如下：

SELECT Max(CHAR_LENGTH(yourColumnName)) AS anyAliasName FROM yourTableName;

要理解上述语法，让我们创建一个表。 创建表的查询如下所示：

mysql> create table CharLengthDemo
   -> (
   -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,
   -> Sentence varchar(255)
   -> );
Query OK, 0 rows affected (0.60 sec)

使用insert命令在表中插入一些记录：

查询如下：

mysql> insert into CharLengthDemo(Sentence) values('Java is an object oriented programming language'
-> );
Query OK, 1 row affected (0.45 sec)
mysql> insert into CharLengthDemo(Sentence) values('MySQL is a Relational Database Management System');
Query OK, 1 row affected (0.26 sec)
mysql> insert into CharLengthDemo(Sentence) values('JSP uses Java Programming Language');
Query OK, 1 row affected (0.24 sec)
mysql> insert into CharLengthDemo(Sentence) values('Object is a root class in java');
Query OK, 1 row affected (0.12 sec)

使用select语句显示表中的所有记录。

查询如下：

mysql> select *from CharLengthDemo;

以下是输出结果：

+----+--------------------------------------------------+
| Id | Sentence                                         |
+----+--------------------------------------------------+
|  1 | Java is an object oriented programming language  |
|  2 | MySQL is a Relational Database Management System |
|  3 | JSP uses Java Programming Language               |
|  4 | Object is a root class in java                   |
+----+--------------------------------------------------+
4 rows in set (0.00 sec)

以下是获取最长varchar长度的查询：

mysql> SELECT Max(CHAR_LENGTH(Sentence)) AS MAXLENGTH FROM CharLengthDemo;

以下是显示具有最长varchar长度值的输出结果：

+-----------+
| MAXLENGTH |
+-----------+
|        48 |
+-----------+
1 row in set (0.00 sec)

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