I encountered this error when doing a multi-table query in mysql
[Err] 1052 - Column 'user_id' in field list is ambiguous
Cause analysis: When a multi-table query is performed, a certain field is shared by two tables. If a certain field is placed in the middle of the select query content from without indicating that it is owned by this or that table, it will occur during query. If the reference is unknown, the above error will appear. As shown
Solution: This error can be solved as long as the field standard in the query is owned by that table.
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