This Gits help you connect to your MySql Database from google sheet, Make surey ou whitelist google IPs ( see the list here https://developers.google.com/apps-script/guides/jdbc#creating_other_database_connections) then go to Tools > Scripts Editor

GoogleSheetMySqlConnection.js

var server = "Your DATABASE HOST";
var databaseName = "DATABASE NAME";
var username = "password";  
var password = "Username"; 
var port = 3306;

/**
 * Open network to Database
 */
function openConnection() {
  // Connection String
  var url = "jdbc:mysql://" + server + ":" + port + "/" + databaseName;
  
  // Open connection
  return conn = Jdbc.getConnection(url, username, password);
}

/**
 * Run Sql Query to fetch mysql Data 
 * and populate them in google sheet
 */
function getResults(sqlQuery){
  var start = new Date(); // Get script starting time
 
  var connection = openConnection();
  
  var statement = connection.createStatement();
  var starttime = new Date(); // Get script starting time
      
  var results = statement.executeQuery(sqlQuery);


  // Google Sheets Details       
  var doc = SpreadsheetApp.getActiveSpreadsheet(); // Returns the currently active spreadsheet
  var cell = doc.getRange('a1');
  var row = 0;
  var getCount = results.getMetaData().getColumnCount(); // Mysql table column name count.
  
  for (var i = 0; i < getCount; i++){  
    cell.offset(row, i).setValue(results.getMetaData().getColumnName(i+1)); // Mysql table column name will be fetch and added in spreadsheet.
  }  

  var row = 1; 
  while (results.next()) {
    
    for (var col = 0; col < results.getMetaData().getColumnCount(); col++) { 
      cell.offset(row, col).setValue(results.getString(col + 1)); // Mysql table column data will be fetch and added in spreadsheet.
    }
    row++;
  }

  results.close();
  statement.close();
  connection.close();
  var end = new Date(); // Get script ending time
  Logger.log('Time elapsed: ' + (end.getTime() - start.getTime())); // To generate script log. To view log click on View -> Logs.
}


/**
 * Get results
 */
function fetchResults(){
  var results = getResults("SELECT * FROM tables;");
}