添加全文索引至所有这些表中的所有字符串列，然后合并结果

Add fulltext indexes to all of the string columns in all of those tables, then union the results

select * from table1 where match(col1, col2, col3) against ('some string')
union all
select * from table2 where match(col1, col2) against ('some string')
union all
select * from table3 where match(col1, col2, col3, col4) against ('some string')
...