SQL

Creating Tables in SQL New tables are defined in a database by entering a CREATE TABLE statement. In its simplest form, the CREATE TABLE statement includes a new table name and one or more column definitions. Tables are removed using the DROP TABLE statement. SQL Syntax for Creating Tables: 1 2 3 4 5 CREATE TABLE table_name ( column1 datatype constraints, column2 datatype constraints, ... ); table_name: The name of the table you want to create. column1, column2, etc.: The names of the columns in the table. datatype: The data type for each column (e.g., INT, VARCHAR, DATE, etc.). constraints: Optional constraints (discussed in the next section) Example: Creating a simple table with basic columns: 1 2 3 4 5 6 7 CREATE TABLE Employees ( EmployeeID INT PRIMARY KEY, FirstName VARCHAR(50), LastName VARCHAR(50), Salary DECIMAL(10, 2), HireDate DATE ); You can check the structure of a specific table using the DESCRIBE statement. For example, ...

Before we learn how to update data in SQL tables, let’s create two tables we will use: customers and orders. customers table 1 2 3 4 5 6 7 8 9 USE ds2; # select database show tables; CREATE TABLE customers ( id INT PRIMARY KEY, name VARCHAR(30) NOT NULL, age INT DEFAULT - 99, address VARCHAR(45), salary DECIMAL(18 , 2 ) DEFAULT 2000.00 ); orders table 1 2 3 4 5 6 7 CREATE TABLE orders ( id INT NOT NULL, date datetime, customer_id INT REFERENCES customers (id), amount DOUBLE, PRIMARY KEY (id) ); Inserting Rows Updating Rows New rows may be inserted into a table one at a time using the SQL INSERT statement. A table name and column list are specified in the INTO clause, and a value list, enclosed in parentheses, is entered in the VALUES clause. ...