Will the query SELECT * FROM Table1 GROUP BY Id be executed?

The query SELECT * FROM Table1 GROUP BY Id will most likely result in an error or unpredictable result in most DBMSs if the selection includes columns that are not part of the GROUP BY clause and are not aggregated by functions.

This is because, when using GROUP BY, all selected columns must either be included in the grouping list or be aggregated (for example, using SUM(), COUNT(), MAX(), etc.). Otherwise, the DBMS cannot unambiguously determine which value to select for non-aggregated columns.

An example of a correct query:

SELECT Id, MAX(OtherColumn) FROM Table1 GROUP BY Id;

If the query specifies SELECT * and only Id is in the GROUP BY, then:

• In MySQL with the ONLY_FULL_GROUP_BY mode enabled, the query will result in an error.
• In some other DBMSs, the query will be rejected.

Thus, the query in its original form is most likely not to execute correctly.