SQL用法总结

1、创建数据库语句

create table persons(
　　'id' INT NOT NULL AUTO_INCREMENT,
　　'lastname' VARCHAR(255) NOT NULL,
　　'firstname' VARCHAR(255) NOT NULL,
　　PRIMARY KEY ('ID'))
DEFAULT CHARACTER SET = latin1
COLLATE = latin1_swedish_ci;

2、创建数据库时，PK、NN、UQ、BIN、UN、AF、AI的含义

PK - Primary Key

NN - Not Null

BIN - Binary (stores data as binary strings. There is no character set so sorting and comparison is based on the numeric values of the bytes in the values.)

UN - Unsigned (non-negative numbers only. so if the range is -500 to 500, instead its 0 - 1000, the range is the same but it starts at 0)

UQ - Create/remove Unique Key

ZF - Zero-Filled (if the length is 5 like INT(5) then every field is filled with 0’s to the 5th value. 12 = 00012, 400 = 00400, etc. )

AI - Auto Increment