Understanding Basic SQL Commands: CREATE, SELECT, INSERT, UPDATE, DELETE

SQL, or Structured Query Language, is a standard language for managing data held in a relational database management system. It is used to communicate with and manipulate databases. In this unit, we will cover some of the most basic and essential SQL commands: CREATE, SELECT, INSERT, UPDATE, and DELETE.

CREATE Command

The CREATE command is used to create a new table in a database. The syntax for the CREATE command is as follows:

CREATE TABLE table_name (
    column1 datatype,
    column2 datatype,
    column3 datatype,
   ....
);

Each column in the table is named, and the datatype of that column is defined.

SELECT Command

The SELECT command is used to select data from a database. The data returned is stored in a result table, called the result-set. The basic syntax of the SELECT statement is as follows:

SELECT column1, column2, ...
FROM table_name;

You can also use the * operator if you wish to select all columns:

SELECT * FROM table_name;

INSERT Command

The INSERT command is used to insert new data into a database. The SQL INSERT INTO syntax is as follows:

INSERT INTO table_name (column1, column2, column3, ...)
VALUES (value1, value2, value3, ...);

If you are adding values for all the columns of the table, you do not need to specify the column names in the SQL query. However, make sure the order of the values is in the same order as the columns in the table.

UPDATE Command

The UPDATE command is used to modify the existing records in a table. The SQL UPDATE Query is used to modify the existing records in a table. You can use the WHERE clause with the UPDATE query to update the selected rows, otherwise all the rows would be affected. The syntax is as follows:

UPDATE table_name
SET column1 = value1, column2 = value2, ...
WHERE condition;

DELETE Command

The DELETE command is used to delete existing records in a table. You can use the WHERE clause with a DELETE query to delete the selected rows, otherwise all the rows would be deleted. The syntax is as follows:

DELETE FROM table_name WHERE condition;

Remember, if you omit the WHERE clause, all records will be deleted!

By understanding these basic SQL commands, you can start to interact with databases by creating tables, inserting new data into them, selecting specific data, updating it, and deleting it when necessary. Practice using these commands until you feel comfortable with them, as they form the foundation for more advanced SQL work.