Mysql-Mysql Query failed. please help. thank you!

Why is the query result empty for clearly-existing data? query the weight field in the weights table! IMG (img.ask.csdn.netupload201508271440637407_784345.jpg )! ####(Img.ask.csdn.netupload20150827144063720._611056.jpg) selectweightfromweightswherefeature & #39; economic factors & #39; this query can be successful, mysqlsql

Why is the query result empty because the data already exists?
Query the weight field in the weights table

Select weight from weights where feature = 'economic times'
This query can be successful, but not when user_id = 'test'