Flash cards
Review the key moves
What is the main idea behind Node.js MySQL Drop Table?
Lesson checks
Practice each idea before moving on
Short Mimo-style checks built from this lesson's code, terms, and sequence.
Which statement best captures the main point of this lesson?
Complete the missing token from the example code.
___ mysql = require('mysql');Put the learning moves in the order that makes the concept easiest to apply.
Delete a Table
You can delete an existing table by using the "DROP TABLE" statement:
Example
Delete the table "customers":
let mysql = require('mysql');
let con = mysql.createConnection({
host: "localhost", user: "yourusername",
password: "yourpassword", database: "mydb"
});
con.connect(function(err) {
if (err) throw err;
let sql = "DROP TABLE customers";
con.query( sql, function (err, result) {
if (err) throw err;
console.log("Table deleted");
});
});Save the code above in a file called "demo_db_drop_table.js" and run the file:
Run "demo_db_drop_table.js"
C:\Users\
Your Name
>node demo_db_drop_table.jsWhich will give you this result
Table deletedDrop Only if Exist
If the the table you want to delete is already deleted, or for any other reason does not exist, you can use the IF EXISTS keyword to avoid getting an error.
Example
Delete the table "customers" if it exists:
let mysql = require('mysql');
let con = mysql.createConnection({
host: "localhost", user: "yourusername",
password: "yourpassword", database: "mydb"
});
con.connect(function(err) {
if (err) throw err;
let sql = "DROP TABLE IF EXISTS customers";
con.query( sql, function (err, result) {
if (err) throw err;
console.log(result);
});
});Save the code above in a file called "demo_db_drop_table_if.js" and run the file:
Run "demo_db_drop_table_if.js"
C:\Users\
Your Name
>node demo_db_drop_table_if.jsIf the table exist, the result object will look like this:
{
fieldCount: 0, affectedRows: 0, insertId: 0,
serverstatus: 2, warningCount: 0, message: '',
protocol41: true, changedRows: 0
}If the table does not exist, the result object will look like this:
{
fieldCount: 0, affectedRows: 0, insertId: 0,
serverstatus: 2, warningCount: 1, message: '',
protocol41: true, changedRows: 0
}As you can see the only differnce is that the warningCount property is set to 1 if the table does not exist.