1. Basic - create db, table

SQL is a Structured query language

1. create / drop database

CREATE DATABASE database_name;

SHOW DATABASES;

USE database_name

DROP DATABASE database_name;

Common Errors and How to Avoid Them

Database Already Exists
If you try to create a database with a name that already exists, you’ll see an error. To avoid this, either choose a new name or use the IF NOT EXISTS clause to only create the database if it doesn't already exist.
Example:

CREATE DATABASE IF NOT EXISTS GeeksForGeeks;

2. create table

CREATE TABLE Customer(  
    CustomerID INT PRIMARY KEY,  
    CustomerName VARCHAR(50),  
    LastName VARCHAR(50),  
    Country VARCHAR(50),  
    Age INT CHECK (Age >= 0 AND Age <= 99),  
    Phone int(10)  
);

here the age column must specify the check criteria

To check weather the table has any criteria use command

SHOW CREATE TABLE tablename;

output

mysql> SHOW CREATE TABLE class1;
+--------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table  | Create Table                                                                                                                                                                                                                                                                                                                       |
+--------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| class1 | CREATE TABLE `class1` (
  `id` int NOT NULL,
  `name` varchar(50) DEFAULT NULL,
  `lastname` varchar(50) DEFAULT NULL,
  `age` int DEFAULT NULL,
  `phone` int DEFAULT NULL,
  PRIMARY KEY (`id`),
  CONSTRAINT `class1_chk_1` CHECK (((`age` > 10) and (`age` < 15)))
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci |
+--------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.01 sec)

mysql>

using the above command we can check wheather any table has a specific criteria

TRUNCATE TABLE:
○ Used to delete the data inside a table, but not the table itself.
○ Syntax – TRUNCATE TABLE table_name