MySQL learning notes

 Queries

1. Create simple tables

CREATE TABLE IF NOT EXISTS Menus (
    id VARCHAR(20) NOT NULL,
    filename VARCHAR(30),
    PRIMARY KEY(id)
) DEFAULT CHARSET=utf8;

CREATE TABLE IF NOT EXISTS Restaurant (
    id VARCHAR(20) NOT NULL,
    name VARCHAR(20) NOT NULL,
    address VARCHAR(100),
    isOpen BOOLEAN,
    menu VARCHAR(20),
    PRIMARY KEY (id),
    FOREIGN KEY(menu) REFERENCES Menus(id)
) DEFAULT CHARSET=utf8;

2. Update existing column's (from not null to null)

ALTER TABLE Menus MODIFY filename VARCHAR(30) NULL;