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SELECT statement limitations

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An aggregate-function column can't be mixed with a non-aggregate column in a SELECT statement.

The select list of a SELECT statement that has a GROUP BY clause can only have expressions from the GROUP BY clause or set functions.

The use of an asterisk (to select all columns) in a SELECT statement containing a GROUP BY clause isn't supported. The names of the columns to be selected must be specified.

The use of a vertical bar in a SELECT statement isn't supported. Use a parameter in the SELECT statement if you need to refer to a data value that contains a vertical bar.

When using a column alias in a SELECT statement, the word "as" must precede the alias. For example, SELECT col1 as a from b. Without the as, the statement returns an error.

If an incorrect column name is entered into a SELECT statement, a SQLSTATE 07001 error, "Wrong Number of Parameters," is returned instead of a SQLSTATE S0022 error, "Column Not Found."

When the Microsoft Excel driver is used, if an empty string is inserted into a column, the empty string is converted to a NULL; a searched SELECT statement that is executed with an empty string in the WHERE clause doesn't succeed on that column.