How do I eliminate duplicate rows in two tables?

How do I get rid of duplicate rows in two tables?

The SQL UNION ALL operator is used to combine the result sets of 2 or more SELECT statements. It does not remove duplicate rows between the various SELECT statements (all rows are returned). Each SELECT statement within the UNION ALL must have the same number of fields in the result sets with similar data types.

How do I eliminate the duplicate rows?

Remove duplicate values1Select the range of cells that has duplicate values you want to remove. Tip: Remove any outlines or subtotals from your data before trying to remove duplicates.2Click Data > Remove Duplicates, and then Under Columns, check or uncheck the columns where you want to remove the duplicates. ... 3Click OK.

How do I delete duplicate rows but keep one?

Remove all duplicates but keep only one with Remove Duplicates function1Select the data list you need, and click Data > Remove Duplicates.2Then in Remove Duplicates dialog, check the column name that you want to remove duplicates from, and if your data has header, check My data has headers option, too. ... 3Click OK.

How do I prevent duplicate rows from joining multiple tables?

ALWAYS put the join predicates in the join. Where clause predicates are not evaluated until after the entire result set has been generated, so unneeded rows are carried along throughout the processing, and in certain outer join scenarios, putting predicates in where clause will generate incorrect results.