Node.js MySQL CHAR_LENGTH()函数
CHAR_LENGTH()函数是 MySQL 中的内置函数,用于获取给定字符串中的字符数。
句法:
CHAR_LENGTH(input_string)
参数:它 接受一个参数如下:
- input_string :它是给定的字符串,其长度要确定。
返回值:它返回给定字符串中的字符数。
模块安装:使用以下命令安装mysql模块:
npm install mysql
数据库:我们的 SQL发布者 带有示例数据的表格预览如下所示:
示例 1:
index.js
const mysql = require("mysql");
let db_con = mysql.createConnection({
host: "localhost",
user: "root",
password: '',
database: 'gfg_db'
});
db_con.connect((err) => {
if (err) {
console.log("Database Connection Failed !!!", err);
return;
}
console.log("We are connected to gfg_db database");
// Here is the query
let query = "SELECT name, CHAR_LENGTH(name)
AS name_length FROM publishers";
db_con.query(query, (err, rows) => {
if(err) throw err;
console.log(rows);
});
});
index.js
const mysql = require("mysql");
let db_con = mysql.createConnection({
host: "localhost",
user: "root",
password: '',
database: 'gfg_db'
});
db_con.connect((err) => {
if (err) {
console.log("Database Connection Failed !!!", err);
return;
}
console.log("We are connected to gfg_db database");
// Here is the query
let query = "SELECT salary, CHAR_LENGTH(salary)
AS salary_length FROM publishers";
db_con.query(query, (err, rows) => {
if(err) throw err;
console.log(rows);
});
});
使用以下命令运行index.js文件:
node index.js
输出:
示例 2:
index.js
const mysql = require("mysql");
let db_con = mysql.createConnection({
host: "localhost",
user: "root",
password: '',
database: 'gfg_db'
});
db_con.connect((err) => {
if (err) {
console.log("Database Connection Failed !!!", err);
return;
}
console.log("We are connected to gfg_db database");
// Here is the query
let query = "SELECT salary, CHAR_LENGTH(salary)
AS salary_length FROM publishers";
db_con.query(query, (err, rows) => {
if(err) throw err;
console.log(rows);
});
});
使用以下命令运行index.js文件:
node index.js
输出: