Node.js MySQL LENGTH()函数
原文:https://www . geesforgeks . org/node-js-MySQL-length-function/
LENGTH() 函数是 MySQL 中的一个内置函数，用于获取给定字符串的长度(以字节为单位)。
语法:
LENGTH(input_string)
参数: LENGTH()函数接受单个参数，如上所述，如下所述。
- input_string: 我们将得到这个字符串的字符数
返回值: LENGTH()函数以字节为单位返回给定字符串的长度。
模块:
- mysql: 处理 mysql 连接和查询
npm install mysql
SQL 发布者表预览:
例 1:
java 描述语言
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 LENGTH('Geeks for Geeks') AS length_in_bytes`;
db_con.query(query, (err, rows) => {
if (err) throw err;
console.log(rows);
});
});
输出:
例 2:
java 描述语言
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, LENGTH(name) AS length_in_bytes FROM publishers`;
db_con.query(query, (err, rows) => {
if (err) throw err;
console.log(rows);
});
});
输出:
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