CREATE TABLE statement

-- Creating a new table
CREATE TABLE table_name (
    column1_name datatype,
    column2_name datatype
);
                                    

Column constraints define the rules that apply to the values within individual columns. A PRIMARY KEY constraint is used to uniquely identify each row in a table. Columns marked as UNIQUE must contain different values for every row. Columns with NOT NULL are required to have a value. The DEFAULT constraint assigns a default value to a column. Each table can have only one PRIMARY KEY column, but it can have multiple UNIQUE columns. The AUTO_INCREMENT attribute is used to automatically generate a unique value for a column, typically for a primary key.

CREATE TABLE table1_name (
    id INTEGER PRIMARY KEY AUTO_INCREMENT,
    name VARCHAR(50) UNIQUE,
    grade INTEGER NOT NULL,
    age INTEGER DEFAULT 10,
    id2 INTEGER,
    FOREIGN KEY (id2) REFERENCES table2_name(id)
);
                                    

*FOREIGN KEY (id2) REFERENCES table2_name(id) - the id2 field from this table is a foreign key referencing the id field from the second table. VARCHAR is a string in SQL, and 50 is its max length (in this example).

INSERT statement

-- Inserting data into columns in the order they are defined in a table
INSERT INTO table_name
VALUES (value1, value2);
                                    

-- Inserting data into columns by their names
INSERT INTO table_name(column1_name, column2_name)
VALUES (value1, value2);
                                    

UPDATE statement

-- Updating data in a table
UPDATE table_name
SET column1_name = value1, column2_name = value2
WHERE some_column_name = some_value;
                                    

ALTER TABLE statement

-- Adding a column to a table
ALTER TABLE table_name
ADD column_name datatype;
                                    

-- Deleting a column from a table
ALTER TABLE table_name
DROP column_name datatype;
                                    

-- Modifying a column's datatype
ALTER TABLE table_name
MODIFY column_name datatype;
                                    

-- Adding a UNIQUE constraint to a column
ALTER TABLE table_name
ADD CONSTRAINT unique_constraint_name UNIQUE (column_name);
                                    

We can add, edit, and delete all constraints and keys similarly. I won't list all those commands here because there are too many. If you want, search the internet for specific instructions.

DELETE statement

-- Deleting data from a table
DELETE FROM table_name
WHERE some_column_name = some_value;
                                    

DROP statement

-- Deleting a table
DROP TABLE table_name;