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Hide rows in table1 if same value found in table2 ?
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Chronological Hierarchical 
If you can change the schema, add a column to store the "deleted" attribute, so you can SELECT ... WHERE NOT deleted.

Otherwise

SELECT ... WHERE NOT EXISTS (SELECT 1 FROM table2 where table2.field == table1.field);

Or

SELECT ... WHERE table1.field NOT IN (SELECT DISTINCT field FROM table2);

Edit: added DISTINCT to above SELECT