Basic operations of databases and tables ----- unique constraints

Basic operation of database and table ----- Unique constraint

** Review the contents of Chapter II **

Basic operation of database and table ----- Create and view databases
Basic operation of database and table ----- Modifying and deleting databases
Basic operation of database and table ----- Classification of data
Basic operation of database and table ----- Create data table
Basic operation of database and table ----- Look at the data sheet
Basic operation of database and table ----- Modify data sheet
Basic operation of database and table ----- Delete data table
Basic operation of database and table ----- Primary key constraint
Basic operation of database and table ----- Non empty constraint
Basic operation of database and table ----- Unique constraint
Basic operation of database and table ----- Default constraint
Basic operation of database and table ----- Set the field value of the table to increase automatically
Basic operation of database and table ----- The concept of index
Basic operation of database and table ----- Create index
Basic operation of database and table ----- Delete index
Basic operation of database and table ----- Phased test II

Preface full name : Onion love code like :Java Programming Important things are to be repeated for 3 times !!! Welcome to visit , learn from each other Welcome to visit , learn from each other Welcome to visit , learn from each other Let's learn about database !!!

Cuddle wood , Born in the end ; A hundred feet platform , From the soil ; A journey , Begins with a single step .------《 Lao tze 》
Today's learning task ！！！！！
1、 Master unique constraints

One 、 Unique constraint

Unique constraint

One quart a day ！！！
Just as Xue Zhiqian is not easy to praise Mao
" You are now a meteor " , But I believe you , If you stick to it, you're a superstar "