mysql get unique values

Key differs from primary keyKey is usually the index synonym. If the keyword attribute primary key is given in the column definition, then primary key can also be specified as key only. The purpose of this is to be compatible with other database

Concept:A primary key (primary key) uniquely identifies a property or group of properties for a row in a table. A table can have only one primary key, but there may be multiple candidate indexes. Primary keys often form referential integrity

How to Use distinct to query multiple unique record values in mysql How to Use distinct to query multiple unique record values in mysql When using mysql, you sometimes need to query records with unique fields. Although mysql provides the keyword

one, key and primary key differenceCREATE TABLE Wh_logrecord (logrecord_id Int (one) not NULL auto_increment,User_name varchar (+) default NULL,Operation_time datetime default NULL,Logrecord_operation varchar (+) default NULL,PRIMARY KEY

one, key and primary key differenceCREATE TABLE Wh_logrecord (logrecord_id Int (one) not NULL auto_increment,User_name varchar (+) default NULL,Operation_time datetime default NULL,Logrecord_operation varchar (+) default NULL,PRIMARY KEY

one, key and primary key differenceCREATE TABLE Wh_logrecord (logrecord_id Int (one) not NULL auto_increment,User_name varchar (+) default NULL,Operation_time datetime default NULL,Logrecord_operation varchar (+) default NULL,PRIMARY KEY

Transferred from: http://zccst.iteye.com/blog/1697043one, key and primary key differenceCREATE TABLEWh_logrecord (logrecord_idint( One) not NULLAuto_increment,user_name varchar( -)default NULL, Operation_timedatetime default NULL,

Transferred from: http://blog.csdn.net/duck_arrow/article/details/8264686Concept:A primary key (primary key) uniquely identifies a property or group of properties for a row in a table. A table can have only one primary key, but there may be multiple

MySQL常用指令，java，php程序员，数据库工程师必备。程序员小冰常用资料整理MySQL common commands (for reference)The most common display commands are:1. Display the list of databases.show databases;2. Display the data table in the library:Use MySQL;Show tables;3, display the

MySQL in the index is very important knowledge points, compared to other knowledge points, the index is more difficult to grasp, and MySQL in the index of a lot of types, such as primary key, unique key and index, etc., this article to introduce you