视图查询

视图查询可以实现不依赖数据库视图的多表查询，并不需要数据库支持视图，例如：

						Db::view
								('User','id,name')
								->view
								('Profile','truename,phone,email','Profile.user_id=User.id')
								->view
								('Score','score','Score.user_id=Profile.id')
								->where
								('score','>',80)
								->select();
						
					

生成的SQL语句类似于：

						SELECT User.id,User.name,Profile.truename,Profile.phone,Profile.email,Score.score
							FROM
							think_user
								User
							INNER JOIN think_profile
								Profile
							ON Profile.user_id=User.id INNER JOIN think_socre Score ON Score.user_id=Profile.id WHERE Score.score > 80
						
					

注意，视图查询无需调用table和join方法，并且在调用where和order方法的时候只需要使用字段名而不需要加表名。

默认使用INNER join查询，如果需要更改，可以使用：

						Db::view
								('User','id,name')
								->view
								('Profile','truename,phone,email','Profile.user_id=User.id','LEFT')
								->view
								('Score','score','Score.user_id=Profile.id','RIGHT')
								->where
								('score','>',80)
								->select();
						
					

生成的SQL语句类似于：

						SELECT User.id,User.name,Profile.truename,Profile.phone,Profile.email,Score.score
							FROM
							think_user
								User
							LEFT JOIN think_profile
								Profile
							ON Profile.user_id=User.id RIGHT JOIN think_socre Score ON Score.user_id=Profile.id WHERE Score.score > 80
						
					

可以使用别名：

						Db::view
								('User',['id'=>'uid','name'=>'account'])
								->view
								('Profile','truename,phone,email','Profile.user_id=User.id')
								->view
								('Score','score','Score.user_id=Profile.id')
								->where
								('score','>',80)
								->select();
						
					

生成的SQL语句变成：

						SELECT User.id AS uid,User.name AS account,Profile.truename,Profile.phone,Profile.email,Score.score
							FROM
							think_user
								User
							INNER JOIN think_profile
								Profile
							ON Profile.user_id=User.id INNER JOIN think_socre Score ON Score.user_id=Profile.id WHERE Score.score > 80
						
					

可以使用数组的方式定义表名以及别名，例如：

						Db::view
								(['think_user'=>'member'],['id'=>'uid','name'=>'account'])
								->view
								('Profile','truename,phone,email','Profile.user_id=member.id')
								->view
								('Score','score','Score.user_id=Profile.id')
								->where
								('score','>',80)
								->select();
						
					

生成的SQL语句变成：

						SELECT member.id
							AS uid,member.name
							AS account,Profile.truename,Profile.phone,Profile.email,Score.score
							FROM think